ECBC User Guide

User Guide
Energy Conservation Building Code

ENERGY CONSERVATION
BUILDING CODE (ECBC)
USER GUIDE
July 2009

Energy Conservation Building Code User Guide
© 2009 Bureau of Energy Efficiency
Published by:
Bureau of Energy Efficiency
4th Floor, Sewa Bhawan, R. K.Puram, New Delhi, India
Developed by:
USAID ECO-III Project
International Resources Group
2, Balbir Saxena Marg, Hauz Khas, New Delhi, India
No portion (graphics or text) of this report may be reproduced, translated, or transmitted in
any form or manner by any means—including but not limited to electronic copy, photocopy,
or any other informational storage and retrieval system without explicit written consent from
Bureau of Energy Efficiency, New Delhi.
All rights reserved
Printed in New Delhi, India
ISBN No. 978-81-909025-3-3
July 2009
This report is made possible by the generous support of the U.S. Government through the ECO-III Project
to the Indian Government. The views expressed in this report do not necessarily reflect the views of partner
countries – United States of America and India – or the United States Agency for International Development.

The Energy Conservation and Commercialization (ECO) Program was signed between the Government
of India (GOI) and USAID in January 2000 under a bilateral agreement with the objective to enhance
commercial viability and performance of Indian energy sector and to promote utilization of clean and
energy-efficient technologies in the sector.
Following the enactment of the Energy Conservation Act 2001, ECO-I Project supported GOI in the
establishment of the Bureau of Energy Efficiency (BEE). Support to BEE was provided to set up procedures
and authorities, establish office facilities and assist in several activities leading to the development of BEE’s
Action Plan including thrust area such as the development of an energy auditor certification program.
ECO-II Project provided BEE with necessary technical assistance and training support to implement three
thrust areas of the Action Plan. The first area was to develop the Energy Conservation Building Codes
(ECBC) for the five climatic zones of India, the second was to support Maharashtra Energy Development
Agency in developing strategies for energy conservation and implementation of selected programs, and the
third area focused on implementing a pilot DSM program to replace incandescent lamps with CFLs in the
state of Karnataka in partnership with BESCOM.
Since November 2006, International Resources Group (IRG), with support from its partners IRG Systems
South Asia, Alliance to Save Energy and DSCL Energy Services, other partner organizations and consultants
has been implementing the ECO-III Project by working closely with BEE, Gujarat Energy Development
Agency, and Punjab Energy Development Agency.
ECBC User Guide has been produced to assist Government of India in the implementation of ECBC,
which was launched by Ministry of Power in May 2007. It is hoped that this document will help in creating
awareness and enhancing understanding about the ECBC. ECO-III Project has developed Tip Sheets and
Design Guides in the past to help in the ECBC implementation efforts. More information as well as electronic
copies of all the publications can be accessed at www.eco3.org.

Foreword
The Energy Conservation Act, 2001(52 of 2001) empowers the Central Government under Section 14(p) read
with Section 56(2)(l) to prescribe Energy Conservation Building Code (ECBC). The Code defines norms and
standards for the energy performance of buildings and their components based on the climate zone in which
they are located.
Under the leadership of Bureau of Energy Efficiency (BEE), a Committee of Experts finalized ECBC in
consultation with various Stakeholders in 2007, with an overall purpose to provide minimum requirements for
the energy-efficient design and construction of buildings. ECBC covers building envelope, heating, ventilation,
and air conditioning system, interior and exterior lighting system, service hot water, electrical power system and
motors.
In May 2007, the Ministry of Power, Government of India formally launched the ECBC for its voluntary
adoption in the country. Since then, BEE has been promoting and facilitating its adoption through several
training and capacity building programmes. BEE is also monitoring implementation of ECBC through the
ECBC Programme Committee (EPC). EPC also reviews periodically the inconsistencies and comments on
ECBC received from various quarters. In this context, BEE in consultation with EPC and support from USAID
ECO-III Project brought out a revised version of ECBC in May 2008.
During the capacity building effort, a need was clearly felt to provide additional guidance to design and
construction professionals on the rationale behind the ECBC specifications and provide explanations to the
key terms and concepts governing these specifications so that people are able to comprehend ECBC in a
better way. Considering this growing need for developing a better understanding of ECBC in the country, the
ECBC User Guide has been prepared under the USAID ECO-III Project in close partnership with BEE. The
document aims to guide and assist the building designers, architects and all others involved in the building
construction industry to implement ECBC in real situations. The document is written both as a reference and as
an instructional guide. It also features examples, best practices, checklists, etc. to direct and facilitate the design
and construction of ECBC-compliant buildings in India.
I am happy to note that the ECBC User Guide Development Team has made a concerted effort to provide
all the information, especially minimum performance standards that buildings need to comply with, in one
place. Consequently, it is my hope that users of ECBC trying to show compliance through the prescriptive
path will find it easier to do so through the guidance provided in the document. The ECBC User Guide also
provides additional guidance on the Whole Building Performance method by making references to international
publications that are widely used by the building design community.
I thank the entire ECBC User Guide Development Team, led by Dr. Satish Kumar, for its extensive efforts in
bringing out this document. I would like to express my sincere appreciation to the USAID for providing this
technical assistance under the ECO-III Project and to the International Resources Group for spearheading this
team effort.
17th July, 2009 (Dr. Ajay Mathur)

ECBC User Guide Development Team
Satish Kumar, Team Leader
IRG, USAID ECO-III Project
Aleisha Khan, Alliance to Save Energy•
Anurag Bajpai, IRG, USAID ECO-III Project•
G. S. Rao, Team Catalyst•
Jyotirmay Mathur, Malviya National Institute•
Technology
Laurie Chamberlain, International Resources•
Group (IRG)
P. C. Thomas, Team Catalyst•
Rajan Rawal, Center for Environmental Planning•
and Technology
Ravi Kapoor, IRG, USAID ECO-III Project•
Surekha Tetali, International Institute of•
Information Technology
Vasudha Lathey•
Vishal Garg, International Institute of•
Information Technology

Acknowledgements
Energy Conservation Building Code (ECBC) User Guide, developed by the USAID ECO-III Project in
association with Bureau of Energy Efficiency (BEE) aims to support the implementation of ECBC.
I would like to thank Dr. Archana Walia, Project Manager, and Mr. S. Padmanaban of USAID for their constant
encouragement and steadfast support during the development process. I would like to acknowledge the
tremendous support and encouragement provided by Dr. Ajay Mathur, Director General, and Mr. Sanjay Seth,
Energy Economist of BEE in the preparation of the Guide.
A substantial undertaking of this nature would not have been possible without the extremely valuable technical
contribution provided by the Development Team of ECBC User Guide especially Ms. Vasudha Lathey, Ms.
Aleisha Khan of Alliance to Save Energy (ASE), Dr. Vishal Garg and Ms. Surekha Tetali of International
Institute of Information Technology (IIIT), Prof. Rajan Rawal of Center for Environmental Planning and
Technology (CEPT), Dr. Jyotirmay Mathur of Malviya National Institute Technology (MNIT), Mr. P. C. Thomas
and Mr. G. S. Rao of Team Catalyst.
I would like to acknowledge the assistance that the Development Team received from the American Society of
Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Inc., USA. The 90.1 User Manual, ANSI/
ASHRAE/IESNA Standard 90.1-2004, provided us with a robust framework and a sound technical reference
during the development of the ECBC User Guide. I am also thankful to Ms. Meredydd Evans of Pacific North-
West National Laboratory (PNNL), and to Saint Gobain, DuPont, ASAHI-India, and Dr. Mahabir Bhandari
(DesignBuilder) for providing inputs on many iterations of this document.
I would like to convey my special thanks to the ECO-III Project Team – Mr. Ravi Kapoor for his substantial
technical contribution to the development of the entire document, Mr. Anurag Bajpai for his tireless efforts in
coordinating inputs from the Development Team members, and Ms. Meetu Sharma for her persistence efforts
to prepare the graphics and desktop layout of multiple iterations of the document. Without the perseverance
and discipline of ECO-III Project Team this work would not have been possible. I also like to thank Ms. Laurie
Chamberlain of International Resources Group (IRG) HQ for assisting us in carrying out technical editing of
this document.
17th July, 2009 (Dr. Satish Kumar)
Chief of Party, USAID ECO-III Project

How to Use This Guide
The ECBC User Guide follows the same structure as the Energy Conservation Building Code. Consequently,
Chapters 1 through 8 and Appendix A through G are identical to the ECBC chapters and the sections within
each chapter also follow the ECBC. Appendix B provides detailed guidance on the Whole Building Performance
method. Assumptions that can be standardized have been included to reduce the chances of gamesmanship
and to create a framework that would allow for “apples to apples” comparison across different projects while
creating simulation models for Standard and Proposed Design. Appendix E is about Climate Zones in India.
This appendix provides a summary of each of the five climate zones and another table that provides a listing of
major Indian cities along with its climatic zone. A new Appendix H has been included that provides a comparison
of International Building Energy Standards. Apart from comparing some of the technical specifications, this
appendix also provides the different approaches taken by countries to check code compliance and enforcement.
It is hoped that this section will provide some ideas to the policy makers on how to make ECBC compliance
mandatory so that minimum energy efficiency performance can be met by buildings coming under the scope
of ECBC.
The ECBC User Guide has been designed in an easy to understand format. The document uses a consistent
format and provides guidance at the following three levels:
Text that is shown in Bluea)
This text is a direct excerpt from the ECBC document and is likely to serve as an anchor for many of the
guidance text and examples included in different chapters. Users interested in showing ECBC compliance
should pay close attention to the text drawn from ECBC and shown in blue. Examples of ECBC text and
ECBC table are reproduced below for guidance:
The Code is applicable to buildings or building complexes that have a connected
load of 500 kW or greater or a contract demand of 600 kVA or greater.
Window Wall Ratio Minimum VLT
0 - 0.3 0.27
0.31-0.4 0.20
Boxed Text showing Tips, Frequently Asked Questions (FAQ), Examples, etc.b)
The Boxed Text provides guidance to the users for better understanding of ECBC concepts and ECBC
applicability in different situations. An example of Boxed Text is shown below:
: Role of Climate ZoneBox 1-A:
The ECBC building envelope requirements are based on the climate zone in which the building
is located. ECBC defines five climate zones (hot-dry; warm-humid; composite; temperate; cold),
which are distinctly unique in their weather profiles (Appendix E). Based on the characteristics
of climate, the thermal comfort requirements in buildings and their physical manifestation in
architectural form are also different for each climate zone
Normal text in blackc)
This type of text forms the core of the ECBC User Guide and provides overall guidance on how best to
understand and apply ECBC.

Table of Contents
USAID ECO-III Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
ECBC User Guide Development Team. . . . . . . . . . . . . . . . . . . . . . . . . . . viii
Acknowledgements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
How to Use This Guide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x
Purpose1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Scope2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Applicable Building Systems2.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Exemptions2.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Safety, Health, And Environmental Codes Take Precedence2.3 . . . . . . . . . . . . . . . . 2
Reference Standards2.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Administration and Enforcement3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Compliance Requirements3.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Mandatory Requirements3.1.1 . . . . . . . . . . . . . . . . . . . . . . . . . . 3
New Buildings3.1.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Additions to Existing Buildings3.1.3 . . . . . . . . . . . . . . . . . . . . . . . . 4
Alterations to Existing Buildings3.1.4 . . . . . . . . . . . . . . . . . . . . . . . 5
Compliance Approaches3.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Administrative Requirements3.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Compliance Documents3.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
General3.4.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Supplemental Information3.4.2 . . . . . . . . . . . . . . . . . . . . . . . . . 11
Building Envelope4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
General4.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Mandatory Requirements4.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Fenestration4.2.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16
Opaque Construction4.2.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Building Envelope Sealing4.2.3 . . . . . . . . . . . . . . . . . . . . . . . . . 18
Prescriptive Requirements4.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Roofs4.3.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Cool Roofs4.3.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Opaque Walls4.3.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Vertical Fenestration4.3.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Skylights4.3.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Building Envelope Trade-Off Option4.4 . . . . . . . . . . . . . . . . . . . . . . . 32
Heating, Ventilation and Air Conditioning5. . . . . . . . . . . . . . . . . . . . . . . . . 33

General5.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Natural Ventilation5.2.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Minimum Equipment Efficiencies5.2.2 . . . . . . . . . . . . . . . . . . . . . . 38
Controls5.2.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Piping and Ductwork5.2.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
System Balancing5.2.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Condensers5.2.6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Economizers5.3.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Variable Flow Hydronic Systems5.3.2 . . . . . . . . . . . . . . . . . . . . . . . 50
Service Water Heating and Pumping6. . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
General6.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Solar Water Heating6.2.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Equipment Efficiency6.2.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Supplementary Water Heating System6.2.3 . . . . . . . . . . . . . . . . . . . . . 55
Piping Insulation6.2.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Heat Traps6.2.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Swimming Pools6.2.6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Compliance Documentation6.2.7 . . . . . . . . . . . . . . . . . . . . . . . . 57
Lighting7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
General7.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Lighting Control7.2.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Exit Signs7.2.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Exterior Building Grounds Lighting7.2.3 . . . . . . . . . . . . . . . . . . . . . 64
Interior Lighting Power7.3.1 . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Building Area Method7.3.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Space Function Method7.3.3 . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Installed Interior Lighting Power7.3.4 . . . . . . . . . . . . . . . . . . . . . . . 67
Exterior Lighting Power7.3.5 . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Electrical Power8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
General8.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Transformers8.2.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Energy-Efficient Motors8.2.2 . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Power Factor Correction8.2.3 . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Check-Metering and Monitoring8.2.4 . . . . . . . . . . . . . . . . . . . . . . . 78
Power Distribution Systems8.2.5 . . . . . . . . . . . . . . . . . . . . . . . . . 78
APPENDIX A: ECBC Definitions, Abbreviations and Acronyms9. . . . . . . . . . . . . . . . A.1
General9.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A.1
Definitions9.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A.1
Abbreviations and Acronyms9.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . A.12
APPENDIX B: Whole Building Performance Method10. . . . . . . . . . . . . . . . . . . . B.1
General10.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B.1
Scope10.1.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B.1
Compliance10.1.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B.2
Annual Energy Use10.1.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . B.3
Trade-offs Limited to Building Permit10.1.4 . . . . . . . . . . . . . . . . . . . . B.3
Documentation Requirements10.1.5 . . . . . . . . . . . . . . . . . . . . . . . B.3
Simulation General Requirements10.2 . . . . . . . . . . . . . . . . . . . . . . . . . B.3
Energy Simulation Program10.2.1 . . . . . . . . . . . . . . . . . . . . . . . . B.3
Climate Data Requirements10.2.2 . . . . . . . . . . . . . . . . . . . . . . . . B.5
Compliance Calculations10.2.3 . . . . . . . . . . . . . . . . . . . . . . . . . . B.5
Calculating the Energy Consumption of the10.3 Proposed Design and the Standard Design. . . . . B.6
The simulation model for calculating the10.3.1 Proposed Design and the Standard Design shall be
developed in accordance with the requirements in Table 10.1. . . . . . . . . . . B.6
APPENDIX C: Default Values for Typical Constructions11. . . . . . . . . . . . . . . . . . . C.1
Procedure for Determining Fenestration Product U-Factor and Solar Heat Gain Coefficient11.1 . . C.1
Default U-factors and Solar Heat Gain Coefficients for Unrated Fenestration Products11.2 . . . . C.2
Unrated Vertical Fenestration11.2.1 . . . . . . . . . . . . . . . . . . . . . . . C.2
Unrated Sloped Glazing and Skylights11.2.2 . . . . . . . . . . . . . . . . . . . . C.2
Typical Roof Constructions11.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . C.2
Typical Wall Constructions11.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . C.3
APPENDIX D: Building Envelope Tradeoff Method12. . . . . . . . . . . . . . . . . . . . D.1
The Envelope Performance Factor12.1 . . . . . . . . . . . . . . . . . . . . . . . . D.1
The envelope performance factor shall be calculated using the following equations.12.1.1 . . D.1
Overhang and Side Fin Coefficients12.1.2 . . . . . . . . . . . . . . . . . . . . . D.2
Baseline Building Definition12.1.3 . . . . . . . . . . . . . . . . . . . . . . . . D.5
APPENDIX E: Climate Zone Map of India13. . . . . . . . . . . . . . . . . . . . . . . . E.1
Climate Zones13.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E.1
APPENDIX F: Air-Side Economizer Acceptance Procedures14. . . . . . . . . . . . . . . . . F.1
Construction Inspection14.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F.1
Equipment Testing14.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F.1
APPENDIX G: ECBC Compliance Forms15. . . . . . . . . . . . . . . . . . . . . . . . G.1
Envelope Summary15.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G.1

Building Permit Plans Checklist15.2 . . . . . . . . . . . . . . . . . . . . . . . . . . G.2
Mechanical Summary15.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G.3
Mechanical Permit Checklist15.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . G.4
Lighting Summary15.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G.5
Lighting Permit Checklist15.6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . G.6
Whole Building Performance Checklist15.7 . . . . . . . . . . . . . . . . . . . . . . . G.7
APPENDIX H: Comparison Of International Building Energy Standards16. . . . . . . . . . . . H.1
APPENDIX I: References17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I.1

List of Tables
Table 4.1: Values of Surface Film Resistance Based on Direction of Heat Flow. . . . . . . . . . . 14
Table 4.2: Thermal Resistances of Unventilated Air Layers Between Surfaces with High Emittance . . . 15
Table 4.3: Comfort Requirements and Physical Manifestations in Buildings . . . . . . . . . . . . . 19
Table 4.4: Roof Assembly U-Factor and Insulation R-value Requirements (ECBC Table 4.3.1). . . . . 21
Table 4.5: Opaque Wall Assembly U-Factor and Insulation R-value Requirements (ECBC Table 4.2). . . 26
Table 4.6: Vertical Fenestration U-factor (W/m2·K) and SHGC Requirements (ECBC Table 4.3). . . . . 26
Table 4.7: Defaults for Unrated Vertical Fenestration (Overall Assembly including Sash and Frame) - Table
11.1 of ECBC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 4.8: SHGC “M” Factor Adjustments for Overhangs and Fins (ECBC Table 4.4) . . . . . . . . . 28
Table 4.9: Minimum VLT Requirements (ECBC Table 4.5). . . . . . . . . . . . . . . . . . . 29
Table 4.10: Skylight U-Factor and SHGC Requirements (ECBC Table 4.6) . . . . . . . . . . . . . 31
Table 5.1: Optimum Size/Number of Fans for Rooms of Different Sizes . . . . . . . . . . . . . 37
Table 5.2: Chillers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Table 5.3: Power Consumption Ratings for Unitary Air Conditioners – Under Test Conditions . . . . . 42
Table 5.4: Power Consumption Ratings for Split Air Conditioners – Under Test Conditions. . . . . . . 42
Table 5.5: Power Consumption Rating for Packaged air Conditioners-under test conditions. . . . . . . 42
Table 5.6: Insulation of Heating Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Table 5.7: Insulation of Cooling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Table 5.8: Ductwork Insulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Table 5.9: Sample R-values for Duct Insulation Materials . . . . . . . . . . . . . . . . . . . . 45
Table 6.1: Standing Loss in Storage Type Electric Water Heaters . . . . . . . . . . . . . . . . . 55
Table 6.2: Insulation of Hot Water Piping.. . . . . . . . . . . . . . . . . . . . . . . . . . 55
Table 7.1: Interior Lighting Power- Building Area Method (ECBC Table 7.1). . . . . . . . . . . . . 66
Table 7.2: Interior Lighting Power- Space Function Method (ECBC Table 7.2). . . . . . . . . . . . 66
Table 7.3: Exterior Lighting Building Power (ECBC Table 7.3) . . . . . . . . . . . . . . . . . . 68
Table 8.1: Dry-Type Transformers (ECBC Table 8.1) . . . . . . . . . . . . . . . . . . . . . . 71
Table 8.2: Oil Filled Transformers (ECBC Table 8.2). . . . . . . . . . . . . . . . . . . . . . 71
Table 8.3: Values of Performance Characteristic of Two Pole Energy-Efficient Induction Motors. . . . . 73
Table 8.4: Values of Performance Characteristic of 4 Pole Energy-Efficient Induction Motors. . . . . . 74
Table 10.1: Modeling Requirements for Calculating Proposed and Standard Design . . . . . . . . . B.7
Table 10.2: Standard Fan Brake Horsepower. . . . . . . . . . . . . . . . . . . . . . . . . B.19
Table 10.3: Type and Number of Chillers . . . . . . . . . . . . . . . . . . . . . . . . . B.19
Table 10.4: Part-Load Performance for VAV Fan Systems. . . . . . . . . . . . . . . . . . . B.20
Table 10.5: HVAC Systems Map (Reproduced from ECBC 10.2) . . . . . . . . . . . . . . . . . B.22
Table 10.6: Electrically Operated Packaged Terminal Air Conditioners. . . . . . . . . . . . . . . B.22

Table 10.7: Building Energy Model Information. . . . . . . . . . . . . . . . . . . . . . . B.23
Table 11.1: Defaults for Unrated Vertical Fenestration (Overall Assembly including the Sash and Frame) . C.2
Table 11.2: Defaults for effective U-Factor for Exterior Insulation layers (under review). . . . . . . . C.2
Table 11.3: Defaults for effective U-factor for Exterior Insulation Layers (under review). . . . . . . . C.3
Table 12.1: Envelope Performance Factor Coefficients-Composite Climate (under review). . . . . . . D.1
Table 12.2: Envelope Performance Factor Coefficients-Hot Dry Climate (under review). . . . . . . . D.2
Table 12.3: Envelope Performance Factor Coefficients-Hot Humid Climate (under review). . . . . . . D.2
Table 12.4: Envelope Performance Factor Coefficients-Moderate Climate (under review) . . . . . . . D.2
Table 12.5: Envelope Performance Factor Coefficients-Cold Climate (under review). . . . . . . . . D.2
Table 12.6: Overhang and Side Fin Coefficients. . . . . . . . . . . . . . . . . . . . . . . . D.3
Table 13.1: Classifications of Different Climate Zones in India . . . . . . . . . . . . . . . . . E.2
Table 13.2: Climate Zone of the Major Indian Cities. . . . . . . . . . . . . . . . . . . . . . E.3

List of Figures
Figure 3.1: Design Process for the Whole Building Performance Method. . . . . . . . . . . . . . . 7
Figure 3.2: The Building Design and Construction Process. . . . . . . . . . . . . . . . . . . . 9
Figure 4.1: Building Envelope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 4.2: The Solar and Blackbody Spectrum. . . . . . . . . . . . . . . . . . . . . . . . 13
Figure 4.3: Schematic Showing Three Modes of Heat Transfer. . . . . . . . . . . . . . . . . . 13
Figure 4.4: Typical Cavity Wall Construction . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 4.5: Direct and Indirect Solar Radiation . . . . . . . . . . . . . . . . . . . . . . . . 16
Figure 4.6: Heat Transfer (Conduction, Convection, & Radiation) and Infiltration Across a Window . . . . 17
Figure 4.7: Building Roofs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 4.8: Typical Insulation Techniques for RCC Roof Construction. . . . . . . . . . . . . . . 24
Figure 4.9: Heat Transfer Through Roof . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Figure 4.10: Projection Calculation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 4.11: Illustration to show U-factor, SHGC, and VLT. . . . . . . . . . . . . . . . . . . 30
Figure 4.12: Skylight Installations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Figure 5.1: Acceptable operative temperature ranges for naturally conditioned spaces.. . . . . . . . . 38
Figure 5.2: Economizer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Figure 6.1: Batch Collector Passive System. . . . . . . . . . . . . . . . . . . . . . . . . . 53
Figure 6.2: Active Indirect System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Figure 6.3: Instantaneous Water Heater. . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Figure 6.4: Heat Trap Elements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Figure 7.1: Relative Efficacy of Major Light Sources (Lumens/Watt) . . . . . . . . . . . . . . . 64
Figure 7.2: Watts per Lighting System Efficiency . . . . . . . . . . . . . . . . . . . . . . . 64
Figure 8.1: Transformer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Figure 8.2: Transformer loss vs % Load. . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Figure 8.3: Increase in efficiency (Percentage points). . . . . . . . . . . . . . . . . . . . . . 76
Figure 8.4: Profile cutaway of an induction motor stator and rotor. . . . . . . . . . . . . . . . . 77
Figure 13.1: Climate Zone Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E.1

Purpose
Energy Conservation Building Code (ECBC) User Guide 1
Purpose1.
The purpose of Energy Conservation Building Code (ECBC) is to provide minimum requirements for
energy-efficient design and construction of buildings and their systems.
The building sector represents about 33% of electricity consumption in India, with commercial sector and
residential sector accounting for 8%and 25% respectively. Estimates based on computer simulation models
indicate that ECBC-compliant buildings can use 40 to 60% less energy than conventional buildings. It is
estimated that the nationwide mandatory enforcement of the ECBC will yield annual savings of approximately
1.7 billion kWh. The ECBC is expected to overcome market barriers, which otherwise result in under-investment
in building energy efficiency.
The ECBC was developed as a first step towards promoting energy efficiency in the building sector. The ECBC
(also referred to as “The Code” in this document) is the result of extensive work by the Bureau of Energy
Efficiency (BEE) and its Committee of Experts. It is written in code-enforceable language and addresses
the views of the manufacturing, design, and construction communities as an appropriate set of minimum
requirements for energy-efficient building design and construction.
For developing the Code, building construction methods across the country were reviewed and various energy-
efficient design and construction practices were evaluated that could reduce energy consumption in building.
In addition, detailed life-cycle cost analyses were conducted to ensure that the Code requirements reflect cost-
effectiveness and practical efficiency measures across five different climate zones in India. While taking into
account different climate zones, the Code also addresses site orientation and specifies better design practices
and technologies that can reduce energy consumption without sacrificing comfort and productivity of the
occupants.
The ECBC User Guide (also referred to as “The Guide” in this document) has been developed to provide
detailed guidance to building owners, designers, engineers, builders, energy consultants, and others on how to
comply with the Code. It provides expanded interpretation, examples, and supplementary information to assist
in applying ECBC during the design and construction of new buildings as well as additions and alterations
to existing buildings. This Guide can also be used as a document by “authorities having jurisdiction” in the
enforcement of the Code once it is made mandatory. The Guide follows the nomenclature of the Code. It
is written both as a reference and as an instructional guide, and can be helpful for anyone who is directly or
indirectly involved in the design and construction of ECBC-compliant buildings.

Scope
Scope2.
The Code is applicable to buildings or building complexes that have a connected load of 500 kW or
greater or a contract demand of 600 kVA or greater.
Generally, buildings or complexes having conditioned area of 1,000 m2 or more will fall under this category.
The Code is presently under voluntary adoption in the country.
This Code would become mandatory as and when it is notified by the Central and State government in the
official Gazette under clause (p) of §14 or clause (a) of §15 of the Energy Conservation Act 2001 (52 of
2001)
Applicable Building Systems2.1
The provisions of the Code apply to:
Building envelopes, except for unconditioned storage spaces or warehouses•
Mechanical systems and equipment, including heating, ventilating, and air conditioning, (HVAC)•
Service hot water heating•
Interior and exterior lighting•
Electrical power and motors•
Specific compliance requirement of the above building components and systems are discussed in Chapter 4
through Chapter 8 of this Guide.
Exemptions2.2
The provisions of this Code do not apply to:
Buildings that do not use either electricity or fossil fuel•
Equipment and portions of building systems that use energy primarily for manufacturing processes•
Safety, Health, And Environmental Codes Take Precedence2.3
Where this Code is found to conflict with safety, health, or environmental codes, the safety, health, or
environmental codes shall take precedence.
Reference Standards2.4
National Building Code (NBC) 2005 is the reference document/standard for lighting levels, HVAC, comfort
levels, natural ventilation, pump and motor efficiencies, transformer efficiencies and any other building materials
and system performance criteria.
The National Building Code 2005 has also been used as a reference in this Guide.
The Code is a dynamic document under continuous maintenance. Addenda, errata, and interpretations can be
issued as and when necessary by the concerned authorities such as the Ministry of Power, the Bureau of Energy
Efficiency, the state governments, etc. This Guide is consistent with ECBC 2007 (revised version, May 2008).
Designers using this Guide should confirm if any addendum has been adopted in the Code by the Authority
Having Jurisdiction before incorporating its requirements in the proposed building’s design.

Administration and Enforcement
Administration and Enforcement3. 1
This chapter addresses administration and enforcement issues, as well as general requirements for demonstrating
compliance with the Code. The compliance requirements of the Code have been made flexible enough to allow
architects and engineers the ability to comply with the Code and meet the specific needs of their projects according to
the climatic conditions of the site.
Compliance Requirements3.1
As mentioned in Chapter 2, all the buildings or building complexes with a connected load of 500 kW or greater
or a contract demand of 600 kVA or greater have to comply with the Code. Buildings with 1,000 m2 or more
of conditioned area are likely to fall under the above load conditions. The following sections which deal with
mandatory and prescriptive requirements of new and existing buildings are related to this specified threshold
area. It is important to mention here that these mandatory and prescriptive requirements are applicable only
where the building has a connected load of 500 kW or more or contract demand of 600kVA or more.
Mandatory Requirements3.1.1
Compliance with the requirements of the Code shall be mandatory for all applicable buildings mentioned under
Chapter 2 of the Code.
New Buildings3.1.2
The Code compliance procedure requires the new building to fulfill a set of mandatory provisions related to
energy use as well as show compliance with the specified requirements stipulated for the different building
components and systems.
The mandatory requirements are described in Sections 4.2, 5.2, 6.2, 7.2, and 8.2 of the Code. These mandatory
provisions are discussed in the corresponding sections of this Guide.
The Code also specifies prescriptive requirements for building components and systems. However, to maintain
flexibility for the design and construction team, the Code compliance requirements can be met by following
one of two methods:
Prescriptive Method1. specifies prescribed minimum energy efficiency parameters for various components
and systems of the proposed building. The prescriptive requirements are covered in Chapter 4 through
Chapter 8 dealing with the building envelope, HVAC systems, service hot water and pumping, lighting
systems, and electric power respectively. To use the building envelope section as an example, designers can
choose the prescriptive method that offers flexibility in selecting insulation for roof that meets specified
thermal characteristic (e.g. R-value, discussed in Chapter 4 of this Guide), in place of meeting prescriptive
requirements of U-factor of the roof assembly. More explanation related to this method can be found in
§3.2.
Whole Building Performance2. (WBP) is an alternative method to comply with the Code. This method is
more complex than the Prescriptive Method, but offers considerable design flexibility. It allows for Code
compliance to be achieved by optimizing the energy usage in various building components and systems
(envelope, HVAC, lighting and other building systems) in order to find the most cost-effective solution.
WBP method requires an approved computer software program to model a Proposed Design, determine its
annual energy use and compare it with the Standard Design of the building. Further explanation on the WBP
Method can also be found in §3.2.
1 This Chapter has been adapted from ASHRAE User Manual (2004).

Box 3-A provides an overview of the ECBC compliance process.
:Box 3-A Steps for meeting ECBC Compliance
Additions to Existing Buildings3.1.3
Existing Building Compliance
The Code also applies to additions in existing buildings. The requirements are triggered when new construction
is proposed in the existing building.
As per the Code:
Where the addition plus the existing building exceeds the conditioned floor area of 1,000 m2 or more, the
additions shall comply with the provisions of Chapter 4 through Chapter 8. Compliance may be demonstrated
in either of the following ways:
The addition alone shall comply with the applicable requirements, or•
The addition, together with the entire existing• building, shall comply with the requirements of this
Code that would apply to the entire building, as if it were a new building
Exception to above:
When space conditioning is provided by existing systems and equipment, the existing systems and equipment
need not comply with this Code. However, any new equipment installed must comply with specific requirements
applicable to that equipment.
ECBC Compliance for Additions to Existing BuildingExample 3.1:
An existing warehouse measures 120 m × 60 m. The warehouse is unconditioned, and the
administrative office (30 m × 30 m) located in one corner. The office is served by a single-zone
rooftop packaged HVAC system that provides both heating and cooling. The owner wants to expand
the administrative office into the warehouse. The new office space will convert an area that measures
30 m × 15 m from unconditioned to conditioned space. The existing HVAC system has sufficient
capacity to serve the additional space. However, new ductwork and supply registers will need to be
installed to serve the additional space.

A: Area of Existing Office = 30m × 30m = 900m2
Additional Area of Office = 30m × 15m = 450m2
However, the Code applies to the 30m × 45m space that is being converted from unconditioned to conditioned
space. The Code does not apply to the existing office or the existing warehouse space. The existing HVAC
system does not need to be modified, but the ductwork extensions must be insulated to the requirements
of §5. The new lighting system installed in the office addition must meet the requirements of §7. The walls
that separate the office addition from the unconditioned warehouse must be insulated to the requirements
of §4. The exterior wall and roof are exterior building envelope components and must meet the Code
requirements.
Source: Adapted from ASHRAE User Manual (2004).
Alterations to Existing Buildings3.1.4
When making alterations to an existing building, the portions of a building and its systems that are being altered
must be made to comply with mandatory and prescriptive requirements.
As per the Code:
Where the existing building exceeds the conditioned floor area threshold (of 1000 m2 or more), portions of a
building and its systems that are being altered shall meet the provisions of Chapter 4 through Chapter 8 (of the
Code). The specific requirements for alterations are described in the following subsections.
Exception to above:
When the entire building complies with all of the provisions of Chapter 4 through Chapter 8 (of the Code) as
if it were a new building.
Building Envelope3.1.4.1
As per the Code:
Alterationstothebuildingenvelopeshallcomplywiththerequirementsof Chapter4(of theCode)orfenestration,
insulation, and air leakage applicable to the portions of the buildings and its systems being altered.
Exception to above:
The following alterations need not comply with these requirements provided such alterations do not increase
the energy usage of the building:
Replacement of glass in an existing sash and frame, provided the U-factor and SHGC of the replacement•
glazing are equal to or lower than the existing glazing
Modifications to roof/ceiling, wall, or floor cavities, which are insulated to full depth with insulation•
Modifications to walls and floors without cavities and where no new cavities are created•
Heating, Ventilation, and Air Conditioning3.1.4.2
As per the Code:
Alterations to building heating, ventilating, and air-conditioning equipment or systems shall comply with the
requirements of Chapter 5 (of the Code) applicable to the portions of the building and its systems being
altered. Any new equipment or control devices installed in conjunction with the alteration shall comply with the
specific requirements applicable to that equipment or control device.

Service Water Heating3.1.4.3
As per the Code:
Alterations to building service water heating equipment or systems shall comply with the requirements of
Chapter 6 applicable to the portions of the building and its systems being altered. Any new equipment or control
devices installed in conjunction with the alteration shall comply with the specific requirements applicable to that
equipment or control device.
Lighting3.1.4.4
As per the Code:
Alterations to building lighting equipment or systems shall comply with the requirements of Chapter 7 applicable
to the portions of the building and its systems being altered. New lighting systems, including controls, installed
in an existing building and any change of building area type as listed in Table 7.1 shall be considered an
alteration. Any new equipment or control devices installed in conjunction with the alteration shall comply with
the specific requirements applicable to that equipment or control device.
Exception to above:
Alterations that replace less than 50% of the luminaires in a space need not comply with these requirements
provided such alterations do not increase the connected lighting load.
Electric Power and Motors3.1.4.5
As per the Code:
Alterations to building electric power systems and motors shall comply with the requirements of Chapter 8 applicable
to the portions of the building and its systems being altered. Any new equipment or control devices installed in
conjunction with the alteration shall comply with the specific requirements applicable to that equipment or control
device.
Compliance Approaches3.2
The Code requires that the building shall comply first with all the mandatory provisions discussed in Chapter
4 to 8 (of the Code). But every building project is different: each building has its own site that presents
unique opportunities and challenges, each building owner or user has different requirements, and climate and
microclimate conditions can vary significantly among projects. Architects and engineers need flexibility in order
to design buildings that address these diverse requirements. The Code provides this flexibility in a number of
ways. Building components and systems have multiple options to comply with the Code requirements. To use the
building envelope section as an example, designers can choose the Prescriptive Method that requires roof insulation
be installed with a minimum R-value. Alternatively, the other options allow the designer to show compliance
with the thermal performance (U-factor) of roof construction assembly. In addition building envelope trade-
off option discussed in Chapter 4 permits trade-offs among building envelope components (roof, walls, and
fenestration) for Code compliance. If more flexibility is needed, the Whole Building Performance Method is
available.
Prescriptive Methoda.
The Code specifies a set of prescriptive requirements for building systems and components. Compliance with
the Code can be achieved by meeting or exceeding the specific levels described for each individual element of
the building systems, covered in Chapter 4 through Chapter 8 of the Code. For building envelope, the Code
provides a Trade-Off option that allows trading off the efficiency of one envelope element with another to
achieve the overall efficiency level required by the Code. The envelope trade-off option is discussed in Chapter
12: Appendix D of ECBC.

Whole Building Performance Methodb.
Use of energy simulation software is necessary to show ECBC compliance via the Whole Building Performance
Method. Energy simulation is a computer-based analytical process that helps building owners and designers
to evaluate the energy performance of a building and make it more energy-efficient by making necessary
modifications in the design before the building is constructed.
These computer-based energy simulation programs model the thermal, visual, ventilation, and other energy-
consuming processes taking place within the building to predict its energy performance. The simulation
program takes into account the building geometry and orientation, building materials, building façade design and
characteristics, climate, indoor environmental conditions, occupant activities and schedules, HVAC and lighting
system and other parameters to analyze and predict the energy performance of the building. Computer simulation
of energy use can be accomplished with a variety of computer software tools and in many cases may be the best
method for guiding a building project to be energy-efficient. However, this approach does require considerable
knowledge of building simulation tools and very close communication between members of the design team.
Appendix B of the Code describes the Whole Building Performance Method for complying with the Code. This
method involves developing a computer model of the Proposed Design and comparing its energy consumption to
the Standard Design for that building. Energy consumption in the Standard Design represents the upper limit of
energy use allowed for that particular building under a scenario where all the prescriptive requirements of the
Code are adopted. Code compliance will be achieved if the energy use in Proposed Design is no greater than the
energy used in the Standard Design. Three basic steps are involved:
Design the1. building with energy efficiency measures; the prescriptive approach requirements provide a
good starting point for the development of the design.
Demonstrate that the2. building complies with the mandatory measures (See sections 4.2, 5.2, 6.2, 7.2, and 8.2).
Using an approved simulation software, model the energy consumption of the3. building using the proposed
features to create the Proposed Design. The model will also automatically calculate the energy use for the
Proposed Design.
If the energy use in Proposed Design is no greater than the energy use in the Standard Design, the building complies
with the Code. Figure 3.1 shows a schematic depicting the WBP method
: Design Process for the Whole Building Performance MethodFigure 3.1
The biggest advantage of using this approach is that it enables the design and construction team to make
comparisons between different design options to identify the most cost-effective and energy-efficient design
solution. For instance, the efficiency of the indoor lighting system might be improved in order to justify

fenestration design that does not meet the prescriptive envelope requirements. As long as the total energy use
of the Proposed Design does not exceed the allowed energy use in Standard Design, the building will be ECBC
compliant.
Note: For a detailed description of the computer simulation process and details, please refer to the ‘Energy
Simulation Tip Sheet’ which can be accessed at: http://eco3.org/downloads/002-Implementationof ECBC/
Energy Simulation (Public Version).pdf
Administrative Requirements3.3
As per the Code:
Administrative requirements relating to permit requirements, enforcement, interpretations, claims of exemption,
approved calculation methods, and rights of appeal are specified by the Authority Having Jurisdiction.
Administration and enforcement of the Code is carried out by the local Authority Having Jurisdiction. This authority
can be responsible for specifying permit requirements, code interpretations, approved calculation methods,
worksheets, compliance forms, manufacturing literature, rights of appeal, and other data to demonstrate
compliance. The Authority Having Jurisdiction will need to receive plans and specifications that show all pertinent
data and features of the building, equipment, and systems.
The process of designing code-compliant buildings will include different stages that begin with the design
process, obtaining a building permit, completing the compliance submittals, the construction of the building
followed by periodic inspections to make sure that construction is taking place per the requirement of the Code.
Box 3-B discusses the Integrated Design Approach and Box 3-C provides guidelines for introducing the Code
compliances and enforcement process. The process of complying with and enforcing the Code will require the
involvement of many parties. Those involved may include the architect or building designer, building developer,
contractor, engineers, energy consultant, owner, officials doing compliance check, and third-party inspectors.
Communication between these parties and an integrated design approach will be essential for the compliance/
enforcement process to run efficiently.
: Integrated Design ApproachBox 3-B
An integrated design approach brings together the various disciplines involved in designing a building and its
systems and reviews their recommendations in a comprehensive manner. It recognizes that each discipline’s
recommendations have an impact on other aspects of the building project. This approach allows for optimization
of both building performance and cost. Often, the architect, mechanical engineer, electrical engineer, contractors,
and other team members pursue their scope of work without adequate interaction with other team members.
This can result in oversized systems or systems that are not optimized for efficient performance. For example,
indoor lighting systems designed without consideration of day lighting opportunities or HVAC systems designed
independently of lighting systems. An integrated design approach allows professionals working in various
disciplines to take advantage of efficiencies that are not apparent when they are working in isolation. It can also
point out areas where trade-offs can be implemented to enhance resource efficiency. The earlier that integration
is introduced in the design process, the greater the benefit.
: The Compliance and Enforcement ProcessBox 3-C
Although the compliance and enforcement process may vary somewhat with each adopting jurisdiction,
the enforcement authority is generally the building department or other agency that has responsibility for
approving and issuing building permits. When non-compliance or omissions are discovered during the plan
review process, the building official may issue a correction list and require the plans and applications to be
revised to bring them into compliance prior to issuing a building permit. In addition, the building official has
the authority to stop work during construction when a code violation is discovered.

The local building department has jurisdiction for determining the administrative requirements relating to
permit applications. They are also the final word on interpretations, claims of exemption, and rights of
appeal. From time to time, the concerned authority will issue interpretations clarifying the intent of the Code.
The local building department may take these under consideration, but the local building department still has
the final word.
To achieve the greatest degree of compliance and to facilitate the enforcement process, the Code should be
considered at each phase of the design and construction process (see Figure 3.2).
At the design phase, designers must understand both the requirements and the underlying intent of the1.
Code. The technical sections of this Guide provide information that designers need to understand how
the Code applies both to individual building systems and to the integrated building design.
At permit application, the design team must make sure that the construction documents submitted with2.
the permit application contain all the information that the building official will need to verify that the
building satisfies the requirements of the Code. (This Guide provides compliance forms and worksheets
to help ensure that all the required information is submitted.)
During plan review, the3. building official must verify that the proposed work satisfies the requirements
of the Code and that the plans (not just the forms) describe a building that complies with the Code. The
building official may also make a list of items to be verified later by the field inspector.
During construction, the contractor must carefully follow the approved plans and specifications. The4.
design professional should carefully check the specifications and working drawings that demonstrate
compliance and should observe the construction in progress to see that compliance is achieved. The
building official must verify that the building is constructed according to the plans and specifications.
After completion of construction, the contractor and/or designer should provide information to the5.
building operators on maintenance and operation of the building and its equipment. Although only
minimal completion and commissioning is required by the Code, most energy efficiency experts agree
that full commissioning is important for proper building operation and management.
Figure 3.2 maps the Design and Construction process along with the Compliances/Enforcement steps
needed to show ECBC compliance.
: The Building Design and Construction ProcessFigure 3.2

Compliance Documents3.4
General3.4.1
As per the Code:
Plans and specifications shall show all pertinent data and features of the building, equipment, and systems in
sufficient detail to permit the Authority Having Jurisdiction to verify that the building complies with the requirements
of this code. Details shall include, but are not limited to:
Building Envelope:
Insulation materials and their R-values•
Fenestration U-factors, SHGC, visible light transmittance (if using the trade-off approach), and air•
leakage
Overhang and sidefin details•
Envelope sealing details•
HVAC:
Type of systems and equipment, including their sizes, efficiencies, and controls•
Economizer details•
Variable speed drives•
Piping insulation•
Duct sealing•
Insulation type and location•
Report on HVAC balancing•
Service Hot Water and Pumping:
Solar water heating system details•
Lighting:
Schedules that show type, number, and wattage of lamps and ballasts•
Automatic lighting shutoff details•
Occupancy sensors and other lighting control details•
Lamp efficacy for exterior lamps•
Electrical Power:
Schedules that show transformer losses, motor efficiencies, and power factor correction devices•
Electric check metering and monitoring system details•
The documents submitted should include sufficient detail to allow thorough review by the Authority Having
Jurisdiction for Code compliance. Additional information may be requested by the authority, if needed, to verify
compliance. The compliance forms and worksheets are provided with this Guide (Appendix G) and are intended
to facilitate the process of complying with the Code. These forms serve a number of functions:
They provide a permit applicant and designer the information that needs to be included on the•
drawing.
They provide a structure and order for the necessary calculations. The forms allow information to be•
presented in a consistent manner, which is a benefit to both the permit applicant and the enforcement
agency.

They provide a roadmap showing the enforcement agency where to look for the necessary information•
on the plans and specifications.
They provide a checklist for the enforcement agency to help structure the drawing check process.•
They promote communication between the drawings examiner and the field inspector.•
They provide a checklist for the inspector.•
Supplemental Information3.4.2
As per the Code:
The Authority Having Jurisdiction may require supplemental information necessary to verify compliance with this
Code, such as calculations, worksheets, compliance forms, manufacturer’s literature, or other data.

Building Envelope
Building Envelope4.
General4.1
Overview
The building envelope refers to the exterior façade, and is comprised of opaque components and
fenestration systems. Opaque components include walls, roofs, slabs on grade (in touch with ground),
basement walls, and opaque doors. Fenestration systems include windows, skylights, ventilators, and
doors that are more than one-half glazed. The envelope protects the building’s interior and occupants
from the weather conditions and shields them from other external factors e.g. noise, air pollution, etc.
The building envelope
depicted here by the green
line, which separates the
conditioned space from the
unconditioned space.
: Building EnvelopeFigure 4.1
Envelope design strongly affects the visual and thermal comfort of the occupants, as well as energy consumption
in the building. Box 4-A discusses the there modes of heat transfer (Conduction, Convection and Radiation) in
the building.
: How Heat Transfer Takes Place in a BuildingBox 4-A
Heat transfer takes place through walls, windows, and roofs in buildings from higher temperature to lower
temperature in three ways-conduction, convection, and radiation. Conduction is the transfer of heat by direct
contact of particles of matter within a material or materials in physical contact. Convection is the transfer
of heat by the movement of a fluid (air or gas or liquid). Radiation is the movement of energy/heat through
space without relying on conduction through the air or by the movement of air.
The surface of the sun, estimated to be at a temperature of about 5500°C, emits electromagnetic waves.
These waves are also known as solar radiation or short-wave radiation with wave length in the range of 0.3 to
2.5 microns or 300 nm to 2500 nm, and has three components: Ultra Violet (UV), Visible (the sun light which
is visible to human eye) and “Solar (or Near) Infrared” as depicted in the figure Figure 4.2:

Building Envelope
Figure 4.2: The Solar and Blackbody Spectrum
When the ‘Solar Infrared’ component of the waves comes in contact with the earth or any object or a building,
it transfers its energy to the object/building in the form of heat. The phenomenon is known as solar radiation
heat transfer. Radiation heat transfer, in fact, can be between any two bodies having different temperatures
with heat transfer taking place from the body at higher temperature to the body at the lower temperature. The
Figure 4.3 shows all three modes of heat transfer across a building wall facing the external environment.
Figure 4.3: Schematic Showing Three Modes of Heat Transfer
Conductive heat transfer across the envelope also depends upon the conductivity of the building material
used. Different materials offer different thermal resistance to the conduction process. Individually, walls and
roofs are comprised of a number of layers composed of different building materials. Thus, it is important to
establish overall thermal resistance and heat transfer coefficient (U-factor), also termed thermal transmittance.
The concepts of thermal resistance and U- factor are discussed in Box 4-B for better understanding.

Building Envelope
Box 4-B: Conduction and Resistance
Conduction
Conduction is heat transfer through a solid medium as a result of a temperature gradient. The heat flow
direction is, in accordance with the second law of thermodynamics, from a region of higher temperature to
that of lower temperature. The Conductivity is the property of material. The rate of heat transfer (q) through
a homogeneous medium is given by Fourier’s Law of Conduction:
q A dx
dT
Wk= 6 @
q : Rate of heat transfer [W]
k : Thermal conductivity of the material [Wm2·K-1]
A : Area [m2]
T : Temperature [K]
x : Distance in the direction of heat flow [m]
Resistance
Thermal Resistance is proportional to the thickness of material of construction and inversely proportional to
its conductivity. This, a lower value of conductivity means less heat flow and so does the greater thickness of
material. Together these parameters form the ‘Thermal Resistance’ to the process of heat conduction.
k
d
m K WR 2 1
= -
6 @· ·
Description of Surface Resistance
The total thermal resistance RT of a plane element consisting of thermally homogeneous layers
perpendicular to the heat flow is calculated by the following formula:
RT : Rsi + Rt + Rse
Where Rt is the thermal resistances of the component in the wall/roof.
Rt : R1 + R2+ …+ Rn
For the calculation of the thermal transmittance under ordinary building conditions, the seasonal mean values
of the exterior surface thermal resistance (Rse) and the interior surface thermal resistance (Rsi) can be obtained
from Table 4.1. These values are the result of empirical studies and merely represent magnitudes of order.
They consider both convection and radiation influences.
: Values of Surface Film Resistance Based on Direction of Heat FlowTable 4.1
Rsi Rse
Direction of Heat Flow Direction of Heat Flow
Horizontal Up Down Horizontal Up Down
0.13 0.10 0.17 0.04 0.04 0.04
Thermal Resistance of an Element Consisting of Homogenous Layers
A building element is usually composed of a number of different materials. When materials are placed in
series, their thermal resistances are added so that the same area will conduct less energy for a given temperature
difference. Formation of air film at the surface of wall or roof, due to convection movements of air, also
provides resistance to the heat flow, similar to the construction material. The total resistance of the wall or
roof includes all of the resistances of the individual materials that make it up as well as both the internal and
external air-film resistance.
R1, R2, …, Rn are the thermal resistance of each layer.
Thermal Resistance is also depicted as reciprocal of Thermal Conductance (U): UR
1
=

Building Envelope
Thermal Resistance of Unventilated Air Layers
Table 4.2 gives the thermal resistances of unventilated air layers (valid for emittance of the bounding surfaces
> 0.8). The values under "horizontal" should be used for heat flow directions ± 30° from the horizontal
plane; for other heat flow directions, the values under "up" or "down" should be used.
Table 4.2: Thermal Resistances of Unventilated Air Layers Between Surfaces with High
Emittance
Thickness of Air Layer
(mm)
Thermal Resistance (m2·K·W-1)
Direction of Heat Flow
Horizontal Up Down
5 0.12 0.10 0.10
7 0.12 0.12 0.12
10 0.14 0.14 0.14
15 0.16 0.16 0.16
25 0.18 0.17 0.18
50 0.18 0.17 0.20
100 0.18 0.17 0.20
300 0.18 0.17 0.21
: R -Value Calculations for Cavity Wall ConstructionExample 4.1
: Typical Cavity Wall ConstructionFigure 4.4
R1: Resistance for Layer 1 (13 mm Gypsum Plaster) = 0.056 K·m2/W (from ECBC Table 11.4)
R2: Resistance of Layer 2 (230 mm brick wall, density=1920kg/m3) = d2/k2 = 0.230/0.81 =0.284 K·m2/W
(from ECBC Table 11.4)
R3: Resistance of Layer 3 (115 mm air gap) =1.8 Km2/W (from Table 4.1)
R4: Resistance of Layer 4 (115 mm brick wall, density=1920kg/m3) = d4/k4 = 0.115/0.81 =0.1426 K·m2/W
(from ECBC Table 11.4)
Rt: Minimum R-value for the composite wall = R1+ R2+ R3 + R4 = 0.056+ 0.2840
+ 0.18 + 0.1426 = 0.6626 K·m2/W
RT: Rsi+ Rt+R se = 0.1+ 0.6626 +0.04= 0.8026
Maximum U-factor for the composite wall: Umin = 1/RT = 1/0.8026 = 1.246 W/m2·K
The design of the building envelope is generally the responsibility of an architect. The building designer is
responsible for making sure that the building envelope is energy-efficient and complies with the mandatory

Building Envelope
and prescriptive requirements of the Code. It also provides ‘trade-off options’ which allows flexibility to the
designer to ‘trade-off’ prescriptive requirements of building components, while meeting the minimum energy
performance requirements of the envelope.
Mandatory Requirements4.2
Fenestration 4.2.1
Heat transfer across glazing products or fenestration (windows, door, and skylights) is similar to the heat transfer
that takes place across walls and roofs through conduction and convection. So, U-factor of glazing is analogous
to the U-factor of wall assembly. In addition, direct solar radiation contributes to the solar heat gain through the
fenestration system. Box 4-C discusses the concept of Solar Heat Gain Coefficient (SHGC).
Fenestration and doors must be rated using procedures and methods specified in the ECBC. Three fenestration
performance characteristics are significant in the ECBC: U-factor, SHGC, and Visible Light Transmittance
(VLT). These are reviewed below:
The U-factor of fenestration is very important to the energy efficiency of buildings, especially in cold climates.
The U-factor must account for the entire fenestration product, including the effects of the frame, the spacers in
double glazed assemblies, and the glazing. There are a wide variety of materials, systems, and techniques used to
manufacture fenestration products, and accurately accounting for these factors is of utmost importance when
calculating the U-factor.
According to ECBC, Fenestration U-factors must be determined in accordance with ISO-15099.
: Solar Heat Gain Coefficient and U-FactorBox 4-C
Conduction heat flow through the fenestration (e.g. glass windows) is similar to the process discussed for walls
and roofs. However regardless of outside temperature, heat gain through the fenestration is also dependent
on direct and indirect solar radiation. The ability to control this heat gain is characterized in terms of SHGC.
SHGC is the ratio of the solar heat gain that passes through the fenestration to the total incident solar radiation
that falls on the fenestration. The solar heat gain includes directly transmitted solar heat and absorbed solar
radiation, which is then re-radiated, convected, or conducted into the interior space. SHGC indicates how well
the glazing/glass and fenestration products insulate heat caused by sun falling directly on the glass.
: Direct and Indirect Solar RadiationFigure 4.5
In hot climates, SHGC is more important than the U-factor of the glazing. A lower SHGC means that lesser
heat can pass through the glazing. The SHGC is based on the properties of the glazing material, whether the
window has single, double, or triple glazing, and the window operation (either operable or fixed). Glazing
units with a low SHGC will help reduce the air conditioning energy use during the cooling season.

Building Envelope
: HeatTransfer (Conduction, Convection, & Radiation) and Infiltration Across aWindowFigure 4.6
U-factors4.2.1.1
Clear glass, which is the most common type of glass used today, has no significant thermal resistance (R-value)
from the pane itself. It has a value of R-0.9 to R-1.0 due to the thin films of air on the interior and exterior surfaces
of the glass. The U-factor (thermal conductance), must account for the entire fenestration system including
the effects of the frame, the spacers in double glazed assemblies, and the glazing. There are a wide variety of
materials, systems, and techniques used to manufacture fenestration products, and accurately accounting for
these factors is of utmost importance when meeting the fenestration requirements. The Code also specifies
U-factor for sloped glazing and skylights, and minimum U-factors for unrated products.
ECBC has used W/m2·C as the unit for U-factor. Since differences in temperature are always denoted in K in
physics literature, ECBC User Guide has used W/m2·K as the unit of U-factor. Wherever, °C was being used
for differences in temperature, it has been replaced with K in the Guide.
U-factors for fenestration systems (including the sash and frame) are required to be determined in accordance
with ISO-15099 (as specified in ECBC §11: Appendix C) by an accredited independently laboratory and labeled
and certified by the manufacturer or other responsible party. Box 4-D briefly explains how these issues are
addressed in US.
Box 4-D: How Fenestration Products areTested, Certified, and Labeled in the U.S.
In the U.S, the fenestration U-factors are determined in accordance with the National Fenestration
Rating Council (NFRC) Standard 100. NFRC is a membership organization of window manufacturers,
researchers, and others that develops, supports, and maintains fenestration rating and labeling procedures.
Most fenestration manufacturers have their products rated and labeled through the NFRC program.
Certified products receive an 8 ½ by 11 inch NFRC label that lists the U-factor, SHGC, and the visible
transmittance.
Solar Heat Gain Coefficient4.2.1.2
The ECBC requires that SHGC be determined in accordance with ISO-15099 by an accredited independent
laboratory, and labeled and certified by the manufacturer or other responsible party. SHGC has replaced Shading
Coefficient (SC) as the preferred specification for solar heat gain through fenestration products.
Designers should insist on getting SHGC data from the manufacturers. However, it should be kept in mind that only
SHGC data that is certified by an accredited independent testing laboratory can be used to show ECBC compliance.

Building Envelope
Air Leakage4.2.1.3
Air leakage for glazed swinging entrance doors and revolving doors shall not exceed 5.0 l/s·m2. Air leakage for
other fenestration and doors shall not exceed 2.0 l/s·m2.
The first set of air leakage requirements deals with inadvertent leaks at joints in the building envelope. In particular,
the standard states that exterior joints, cracks, and holes in the building envelope shall be caulked, gasketed, weather
stripped, or otherwise sealed. The construction drawings should specify sealing, but special attention is needed in the
construction administration phase to assur e proper workmanship. A tightly constructed building envelope is largely
achieved through careful construction practices and attention to detail. Poorly sealed buildings can cause problems for
maintaining comfort conditions when additional infiltration loads exceed the HVAC design assumptions. This can be
a significant problem in high-rise buildings due to stack effect and exposure to stronger winds.
Opaque Construction4.2.2
U-factors shall be determined from the default tables in Appendix C §11 or determined from data or procedures
contained in the ASHRAE Fundamentals, 2005.
Building Envelope Sealing4.2.3
Air leakage can also occur through opaque construction. Apart from adding cooling or heating load in the
building, air leakage can cause condensation within walls and roof can damage insulation material and degrade
other building materials. Box 4-E discusses these aspects in more detail.
Itmustbenotedthatbuildingsealingismoreimportantinair-conditionedbuildings.Innaturallyventilatedbuildings,
the concept of building ceiling and tight envelope runs counter to conventional and traditional wisdom.
Box 4-E: Building Envelope Sealing and Air Leakage
Air leakage is the passage of air through a building envelope, wall, window, joint, etc. Leakage to the interior
is referred to as infiltration and leakage to the exterior is referred to as ex-filtration. Excessive air movement
significantly reduces the thermal integrity and performance of the envelope and is, therefore, a major
contributor to energy consumption in a building.
A tightly constructed building envelope is largely achieved through careful construction practices and attention to
detail. Building envelopes should be carefully designed to limit the uncontrolled entry of outdoor air into the building.
Air leakage introduces sensible heat into conditioned spaces. In climates with moist outdoor conditions, it is also a
major source of latent heat. Latent heat must be removed by the air-conditioning system at considerable expense.
In addition to causing energy loss, excessive air leakage can cause condensation to form within and on walls.
This can create many problems including reducing insulation R-value, permanently damaging insulation, and
seriously degrading materials.
It can rot wood, corrode metals, stain brick or concrete surfaces, and in extreme cases cause concrete to break,
bricks to separate, mortar to crumble and sections of a wall to fall jeopardizing the safety of occupants. It
can corrode structural steel, re-bar, and metal hangars and bolts with very serious safety and maintenance
consequences. Moisture accumulation in building materials can lead to the formation of mold that may
require extensive remedying the situation.
Virtually anywhere in the building envelope where there is a joint, junction or opening, there is potential for
air leakage. Air leakage will cause the HVAC system to run more often and longer at one time, and still leave
the building uncomfortable for its occupants.
All openings in the building envelope, including joints and other openings that are potential sources of air
leakage, should be to be sealed to minimize air leakage. It means that all gaps between wall panels, around doors,
and other construction joints must be well sealed. Ceiling joints, lighting fixtures, plumbing openings, doors, and
windows should all be considered as potential sources of unnecessary energy loss due to air infiltration.
ECBC identifies several areas in the building envelope where attention should be paid to infiltration control.
These include:

Building Envelope
Joints around fenestration and doorframes.a.
Openings at penetrations of utility services through roofs, walls, and floors.b.
Site-built fenestration and doors.c.
Building assemblies used as ducts or plenums.d.
Joints, seams, and penetrations of vapor retarders.e.
All other openings in the building envelope.f.
It is also recommended that junctions between walls and foundations, between walls at building corners, between
walls and structural floors or roofs, and between walls and roof or wall panels.
Fenestration products, including doors, can also significantly contribute to infiltration. Although not included in
the Code, it is recommended that fenestration products should have infiltration less than 0.4 cfm/ft² (2.0 l/s·m²).
For glazed entrance doors that open with a swinging mechanism and for revolving doors, it is recommended
that infiltration be limited to 1.0 cfm/ft² (5.0 l/s·m²).
Prescriptive Requirements4.3
For envelope component-based compliance approach, ECBC sets requirements for:
Exterior roofs and ceilings•
Cool roofs•
Opaque walls•
Vertical fenestration•
Skylights•
Roofs4.3.1
In roofs, the U-factor for the overall assemblies or minimum R-values for the insulation must be complied with
the provisions of the Code. ECBC Appendix C provides values for typical constructions.
In real practice, the heat gains through the walls, roof, and fenestration depends upon the climate zone in which
the building is located. The National Building Code of India, 2005 has divided the country in five climate zones
(Hot-Dry; Warm-Humid; Composite; Temperate/Moderate; and Cold), and the air temperature and humidity
variations that exist need to be considered while designing the building envelope.
: Role of Climate ZoneBox 4-F
The ECBC building envelope requirements are based on the climate zone in which the building is located.
ECBC defines five climate zones (hot-dry; warm-humid; composite; temperate; cold), which are distinctly
unique in their weather profiles. Appendix E of the Guide provides additional information on the five
climatic zones. Based on the characteristics of climate, the thermal comfort requirements in buildings and
their physical manifestation in architectural form are also different for each climate zone (See Table 4.3).
These physical manifestations, in turn, dictates the ECBC requirements for the envelope, as well as other
building components that are applicable to the building.
Table 4.3: Comfort Requirements and Physical Manifestations in Buildings
HOT AND DRY CLIMATE ZONE
Thermal Requirements Physical Manifestation
Reduce Heat Gain
Decrease exposed surface area Orientation and shape of building
Increase thermal resistance Insulation of building envelope
Increase thermal capacity (Time lag) Massive structure
Increase buffer spaces Air locks/lobbies/balconies/verandahs
Decrease air exchange rate (ventilation during day-time) Smaller windows openings, night ventilation
Increase shading External surfaces protected by overhangs, fins and trees

Building Envelope
Increase surface reflectivity Pale colour, glazed china mosaic tiles etc.
Reduce solar heat gain Use glazing with lower SHGC and provide shading for windows.
Minimize glazing in East and West
Promote Heat Loss
Increase air exchange rate (Ventilation during night-time) Courtyards/wind towers/arrangement of openings
Increase humidity levels Trees, water ponds, evaporative cooling
WARM AND HUMID CLIMATE ZONE
Reduce Heat Gain
Increase thermal resistance Roof insulation and wall insulation
Reflective surface of roof
Increase buffer spaces Balconies and verandas
Increase shading Walls, glass surfaces protected by overhangs, fins and trees
Increase surface reflectivity Pale color, glazed china mosaic tiles, etc.
Promote Heat Loss
Increase air exchange rate (Ventilation throughout the day) Ventilated roof construction. Courtyards, wind towers and
arrangement of openings
Decrease humidity levels Dehumidifiers/desiccant cooling
MODERATE CLIMATE ZONE
Reduce Heat Gain
Increase thermal resistance Roof insulation and east and west wall insulation
Increase shading East and west walls, glass surfaces protected by overhangs, fins and
trees
Increase surface reflectivity Pale colour, glazed china mosaic tiles, etc.
Promote Heat Loss
Increase air exchange rate (Ventilation) Courtyards and arrangement of openings
COLD (Cloudy/Sunny) CLIMATE ZONE
Reduce Heat Loss
Decrease exposed surface area Orientation and shape of building. Use of trees as wind barriers
Increase thermal resistance Roof insulation, wall insulation and double glazing
Increase thermal capacity (Time lag) Thicker walls
Increase buffer spaces Air locks/Lobbies
Decrease air exchange rate Weather stripping and reducing air leakage
Increase surface absorptive Darker colours
Promote Heat Gain
Reduce shading Walls and glass surfaces
Trapping heat Sun spaces/green houses/Trombe walls etc.
COMPOSITE CLIMATE ZONE
Reduce Heat Gain in Summer and Reduce Heat Loss in Winter
Decrease exposed surface area Orientation and shape of building. Use of trees as wind barriers
Increase thermal resistance Roof insulation and wall insulation
Increase thermal capacity (Time lag) Thicker walls

Building Envelope
Increase buffer spaces Air locks/Balconies
Decrease air exchange rate Weather stripping
Increase shading Walls, glass surfaces protected by overhangs, fins and trees
Increase surface reflectivity Pale color, glazed china mosaic tiles, etc.
Promote Heat Loss in Summer/Monsoon
Increase air exchange rate (Ventilation) Courtyards/wind towers/arrangement of openings
Increase humidity levels in dry summer Trees and water ponds for evaporative cooling
Decrease humidity in monsoon Dehumidifiers/desiccant cooling
Source: Nayak and Prajapati (2006). Handbook on Energy Conscious Buildings
Exterior roofs can meet the prescriptive requirements in one of two ways:
Use the required R-value of the insulation (this R-value does not apply to building materials or air film.•
It should be referred exclusively for insulation), or
Use a roof assembly U-factor that meets the maximum U-factor criterion for thermal performance (see•
ECBC Table 4.3.1). The U-factor takes into account all elements or layers in the construction assembly,
including the sheathing, interior finishes, and air gaps, as well as exterior and interior air films.
As per the Code:
The roof insulation shall not be located on a suspended ceiling with removable ceiling panels.
The Code requirements for the U-factor and R-values for 24 hours use buildings and daytime use buildings for
five climate zones as shown in Table 4.4 below.
Table 4.4: Roof Assembly U-Factor and Insulation R-value Requirements (ECBC Table 4.3.1)
Climate Zone 24-Hour use buildings Hospitals,
Hotels, Call Centers etc.
Daytime use buildings Other Building
Types
Maximum U-factor of
the overall assembly
(W/m2·K)
Minimum R-value
of insulation alone
(m2·K/W)
Maximum U-factor of
(W/m2·K)
Minimum R-value
of insulation alone
(m2·K/W)
Composite U-0.261 R-3.5 U-0.409 R-2.1
Hot and Dry U-0.261 R-3.5 U-0.409 R-2.1
Warm and Humid U-0.261 R-3.5 U-0.409 R-2.1
Moderate U-0.409 R-2.1 U-0.409 R-2.1
Cold U-0.261 R-3.5 U-0.409 R-2.1
Some recommended practices for proper installation and protection of insulation are provided below:
Insulation
The first set of mandatory requirements addresses the proper installation and protection of insulation materials.
It is recommended that insulation materials be installed according to the manufacturer’s recommendations and
in a manner that will achieve the rated insulation R-value. Compressing the insulation reduces the effective
R-value and the thermal performance of the construction assembly.
Substantial Contact
It is recommended that insulation be installed in a permanent manner and in substantial contact with the inside
surface of the construction assembly. If the insulation does not entirely fill the cavity, the air gap should be
on the outside surface. Maintaining substantial contact is particularly important (and problematic) for batt
insulation installed between floor joists. Without proper support, gravity will cause the insulation to fall away
from the floor surface, leaving an air gap above the insulation. Air currents will ultimately find their way to the
gap, and when they do, the effectiveness of the insulation will be substantially reduced.

Building Envelope
Insulation Above Suspended Ceilings
It is not good practice to install insulation directly over suspended ceilings with removable ceiling panels.
This is because the insulation’s continuity is likely to be disturbed by maintenance workers. Also, suspended
ceilings may not meet the ECBC’s infiltration requirements unless they are properly sealed. Compliance with
this requirement could have a significant impact in some parts of the country, as it is common practice to install
insulation over suspended ceilings. Many building codes will consider the space above the ceiling to be an attic
and require that it be ventilated to the exterior. If vented to the exterior, air in the attic could be quite cold (or
hot) and the impact of the leaky suspended ceiling would be made worse.
Insulation Protection
It is strongly recommended that insulation be protected from sunlight, moisture, landscaping equipment, wind,
and other physical damage. Rigid insulation used at the slab perimeter of the building should be covered to prevent
damage from gardening or landscaping equipment. Rigid insulation used on the exterior of walls and roofs should
be protected by a permanent waterproof membrane or exterior finish. In general, a prudent designer should pay
attention to moisture migration in all building construction. Vapor retarders prevent moisture from condensing
within walls, roofs, or floors but care should be taken to install them on the correct side (warmer or cooler side)
of the walls and roofs to prevent water damage. Water condensation can damage the building structure and can
seriously degrade the performance of building insulation and create many other problems such as mold and
mildew. The designer should evaluate the thermal and moisture conditions that might contribute to condensation
and make sure that vapor retarders are correctly installed to prevent condensation. In addition to correctly installing
a vapor retarder, it is important to provide adequate ventilation of spaces where moisture can build up.
Figure 4.7 shows some common techniques to insulate different types of roofing systems.
Pre-Fabricated Metal Roofs Showing Thermal Blocking of Purlins
Steel Joist Roof with Insulated Cavities
Metal Framed Ceiling Insulation

Building Envelope
Insulation entirely above deck: Insulation is installed above
(a) concrete, (b) wood or (c) metal deck in a continuous manner. (a), (b), and (c) are shown sequentially right to left.
Steel Joist Roof with Continuous Insulation
: Building RoofsFigure 4.7
A. RCC Slab Insulated with Vermiculite
B. RCC Slab Insulated with Earthen Pots

Building Envelope
C. RCC Slab Insulated using Foamular Metric
: Typical Insulation Techniques for RCC Roof ConstructionFigure 4.8
Cool Roofs4.3.2
Depending on the material and construction, a roof will have different properties that determine how it
conducts heat to the inside of the building. “Cool roofs” are roofs covered with a reflective coating that has a
high emissivity property that is very effective in reflecting the sun’s energy away from the roof surface. These
“cool roofs” are known to stay 10°C to 16°C cooler than a normal roof under a hot summer sun; this quality
greatly reduces heat gain inside the building and the cooling load that needs to be met by the HVAC system. Box
4-G discusses how solar heat radiation is reflected, absorbed and emitted from the roof and how these concepts
are used in developing cool roofs.
Box 4-G: Reflectance, Absorptance, and Emissivity
The heat transfer process involved in the roof, is similar to the heat transfer that takes in a wall. Heat transfer
across the roof is more prominent compared to the wall because of higher incidence of solar radiation.
Depending on the properties of the roof material and construction, the roof reflects part of the solar
radiation back to the environment, and absorbs the other part of the heat in the roof (See Figure 4.9). Finally,
portion of the absorbed heat in the roof is emitted as long-wave radiation back to the environment and
the remaining part of the absorbed heat is conducted inside of the building. This heat transfer process is
governed by the Solar Reflectance and Emissivity (Thermal Emittance) properties of the roof material, apart
from the thermal conductivity of the materials used in the roof.
Figure 4.9: Heat Transfer Through Roof

Building Envelope
Solar Reflectance and Absorptance
The solar reflectance is the fraction of solar radiation reflected by roof. The complement of reflectance is
absorptance; whatever radiant energy incident on a surface that is not reflected is absorbed in the roof. The
reflectance and absorptance of building materials are usually measured across the solar spectrum, since these
are exposed to that range of wavelength.
Reflectance is measured on a scale of 0 to 1, with 0 being a perfect absorber and 1 being a perfect reflector.
Absorptance is also rated from 0 to 1, and can be calculated from the relation: Reflectance + Absorptance = 1.
Emissivity or Thermal Emittance
Emissivity (or thermal emittance) of a material (usually written ε or e) is the ratio of energy radiated by a
particular material to energy radiated by a black body at the same temperature. It is a measure of a material’s
ability to radiate the absorbed energy. A true black body would have an e =1 while any real object would have
e <1. Emissivity is a dimensionless quantity (does not have units). In general, the duller and blacker a material
is, the closer it’s emissivity is to 1. The more reflective a material is, the lower its emissivity.
The emissivity of building material, unlike reflectance, is usually measured in the far infrared part of the
spectrum.
Ideal Exterior Surface
An ideal exterior surface coating of a building in hot climate and under indoor cooling would have reflectance
near 1, and absorptance near zero, and Emissivity near 1 to radiate absorbed heat back to the sky.
If designing a cool roof, requirements for minimum solar reflectance and initial emittance levels are specified
[ECBC 4.3.1.1].
Roofs with slopes less than 20° shall have an initial solar reflectance of no less than 0.70 and an initial emittance
no less than 0.75. Solar reflectance shall be determined in accordance with ASTM E903-96 and emittance shall
be determined in accordance with ASTM E408-71 (RA 1996).
: Cool RoofsBox 4-H
In hot climates, cool roofs (or high emissivity or thermal emittance roof surfaces) are an effective way to
reduce solar gains and cut building owners’ energy costs. Because cool roofs gain less heat than normal
roofs, they reduce the need for air conditioning and make buildings more comfortable to the people
inside. The light color reflects sunlight and heat away from the building, and the high emissivity or thermal
emittance allows heat to escape to the atmosphere when the surface becomes heated. Although some
surfaces, such as galvanized metal, have a high reflectance, they have a low emittance. These surfaces
reflect heat, but heat that is absorbed cannot escape. Other surfaces, such as dark paint, have a high
emittance but a low reflectance. These surfaces allow heat to escape, but do a poor job of reflecting heat
that strikes the surface.
Most cool roof materials for low-sloped roofs are white or another light color. For steep-sloped roofs that
are often visible from the ground, roofing material manufacturers have developed popular roof colors
other than white that will still reflect solar radiation or emit the sun’s energy away from the building.
Cool roofs have other benefits in addition to reducing operating absorbed heat costs. For building owners,
they can cut maintenance costs and increase the life expectancy of the roof. For society in general, cool
roofs can even help to reduce the urban heat island effect and slow down global warming that makes our
cities hotter and produces unhealthy air.
What is meant by Urban Heat Island effect?
An Urban Heat Island is a metropolitan urban area, which is significantly warmer than its surroundings.
As population centers grow in size, they tend to have a corresponding increase in average temperature.
Scientists refer to this phenomenon as the “Urban Heat Island Effect”. The two main causes of the urban
heat island is modification of the land surface by urban development and waste heat generated by energy
usage. One consequence of urban heat islands is the increased energy required for air conditioning and
refrigeration in cities that are in comparatively hot climates.

Building Envelope
What types of roofing products are available?
Products for low-slope roofs, found on commercial and industrial buildings fall into two categories: single-ply
materials and coatings. Single-ply materials are large sheets of pre-made roofing that are mechanically fastened
over the existing roof and sealed at the seams. Coatings are applied using rollers, sprays, or brushes, over an
existing clean, leak-free roof surface. Products for sloped roofs are currently available in clay, or concrete tiles.
These products stay cooler by the use of special pigments that reflect the sun’s infrared heat. In India, lime
coats, white tiles grouted with white cement, special paints, etc. are used as cool roofing materials.
Opaque Walls4.3.3
Opaque walls can meet the prescriptive requirements by either using a construction that has an assembly
U-factor lower than the specified value as shown in ECBC Table 4.2 (reproduced in Table 4.5), or by using
insulation with R-value more than the prescribed value. R-value is for the insulation alone and does not include
building materials or air films.
Table 4.5: Opaque Wall Assembly U-Factor and Insulation R-value Requirements (ECBC Table 4.2)
Climate Zone Hospitals, Hotels, Call Centers
(24-Hour)
Other Building Types (Daytime)
Maximum U-factor of
(W/m2·K)
Minimum R-value
of insulation alone
(m2·K/W)
Maximum U-factor
of the overall
assembly (W/m2·K)
Minimum R-value
of insulation alone
(m2·K/W)
Composite U-0.440 R-2.10 U-0.440 R-2.10
Hot and Dry U-0.440 R-2.10 U-0.440 R-2.10
Warm and Humid U-0.440 R-2.10 U-0.440 R-2.10
Moderate U-0.440 R-2.10 U-0.440 R-2.10
Cold U-0.369 R-2.20 U-0.352 R-2.35
Vertical Fenestration4.3.4
The ECBC limits the area of vertical fenestration, under the prescriptive approach, to a maximum of 60% of
the gross wall area.
The ECBC addresses energy losses through fenestration by specifying the following requirements: maximum
U-factor (or thermal transmittance) and maximum SHGC, for the following window to wall ratio (WWR):
WWR up to 40% and•
WWR in the range of more then 40% and up to 60%•
Vertical fenestration should meet the requirements for maximum area weighted U-factor and maximum area
weighted SHGC.
The U-factor and SHGC requirements of the rated (labeled) fenestration for two WWR ranges for Code
compliance are given in Table 4.3 of ECBC (reproduced in Table 4.6.
Table 4.6: Vertical Fenestration U-factor (W/m2·K) and SHGC Requirements (ECBC Table 4.3)
WWR≤40% 40% <WWR≤60%
Climate Maximum U-factor Maximum SHGC Maximum SHGC
Composite 3.30 0.25 0.20
Hot and Dry 3.30 0.25 0.20
Warm and Humid 3.30 0.25 0.20
Moderate 6.90 0.40 0.30
Cold 3.30 0.51 0.51
See Appendix C of ECBC for default values of unrated fenestration values for unrated windows must follow
the values given in Table 11.1 of Appendix C of ECBC.

Building Envelope
: Defaults for Unrated Vertical Fenestration (Overall Assembly including Sash andTable 4.7
Frame) - Table 11.1 of ECBC
Frame Type Glazing Type Clear Glass Tinted Glass
U-factor
(W/m2·K)
SHGC VLT U-Factor
(W/m2·K)
SHGC VLT
All frame types Single Glazing 7.1 0.82 0.76 7.1 0.70 0.58
Wood, vinyl, or fiberglass frame Double Glazing 3.3 0.59 0.64 3.4 0.42 0.39
Metalandotherframetype Double Glazing 5.1 0.68 0.66 5.1 0.50 0.40
: Energy-Efficient Fenestration Products/Assemblies.Box 4-I
Windows are affected by many factors, which in turn affect the comfort and energy performance of buildings.
Understanding these factors is critical in designing buildings that meet the needs of building owners and users.
Once these factors are identified, a designer can then apply the appropriate technology to address them.
A fenestration product is comprised of three areas: the vision area, the glazing, and the opaque area or the
frame. In a window, glazing is generally 90-95% of the total area and therefore the most important part
to address for achieving energy efficiency. However, the frame becomes important to optimize the overall
energy efficiency of the window.
The energy efficiency of a fenestration product is affected by:
Films which are applied to improve energy efficiency•
Low emissivity (low-e) coatings for energy-efficient windows•
Gas fill used in insulating glass units for energy-efficient windows•
Insulating glass units for energy-efficient windows•
Frame designs for energy-efficient windows•
Reducing the air leakage of windows to improve energy efficiency•
Number of layers of glass in the fenestration product.•
The technology for producing energy-efficient windows relies heavily on the development of coatings for glass.
A low-e coating allows the visible light to pass through relatively unaffected whole rejecting invisible infrared
heat. For example, an emissivity of 0.10 means that 90% of the long heat radiation is reflected back.
There are a large number of glazing products that are available from different manufacturers complying with
the ECBC requirements for fenestrations.
Exception to ECBC §4.3.3: The SHGC requirement of a window can be affected by overhangs on a building,
which reduce solar gains. The ECBC uses a term called a projection factor to determine how well an overhang
shades the building’s glazing. The projection factor is calculated by measuring the distance from the window
to the farthest edge of the overhang and dividing that by the distance from the bottom of the window to the
lowest point of the overhang demonstrates how to calculate a projection factor.
Projection Factor = H (horizontal)/V (vertical)
The ECBC provides a modified SHGC requirement where there are overhangs and/or side fins, which are
a permanent part of the building. This may be applied in determining the SHGC for the Proposed Design.
An adjusted SHGC, accounting for overhangs and/or sidefins, is calculated by multiplying the SHGC of the
unshaded fenestration product by a multiplication (M) factor. If this exception is applied, a separate M Factor
shall be determined for each orientation and unique shading condition.

Building Envelope
Solar heat gain Coefficient•
Requirements dependent on:•
Overhang projection factor•
M- Factor from Table 4.3.3-2•
Orientation•
And Climate Zone•
Without Overhang: SHGC range 0.25-0.51 based on climate zone.•
PF= Ratio of overhang projection divided by height from window sill to bottom•
of overhang (must be permanent)
: Projection CalculationFigure 4.10
ECBC Table 4.4 provides the values of M-factor for various projection factors.
Table 4.8: SHGC“M”Factor Adjustments for Overhangs and Fins (ECBC Table 4.4)
Overhang “M”
Factors for 4
Projection Factors
Vertical Fin “M”
Factors for 4
Projection Factors
Overhang +Fin
“M” Factors for 4
Projection Factors
Project Location Orientation 0.25
-
0.49
0.50
-
0.74
0.75
-
0.99
1.00
+
0.25
-
0.49
0.50
-
0.74
0.75
-
0.99
1.00
+
0.25
-
0.49
0.50
-
0.74
0.75
-
0.99
1.00 +
North latitude 15°
or greater
N .88 .80 .76 .73 .74 .67 .58 .52 .64 .51 .39 .31
E/W .79 .65 .56 .50 .80 .72 .65 .60 .60 .39 .24 .16
S .79 .64 .52 .43 .79 .69 .60 .56 .60 .33 .10 .02
Less than 15°
North latitude
N .83 .74 .69 .66 .73 .65 .57 .50 .59 .44 .32 .23
E/W .80 .67 .59 .53 .80 .72 .63 .58 .61 .41 .26 .16
S .78 .62 .55 .50 .74 .65 .57 .50 .53 .30 .12 .04
: Prescriptive Requirements for FenestrationExample 4.2
Location : Chandigarh
Climate Zone : Composite (Lat: 30° 42’ N; Long: 76° 54’ E)
Building Type : Daytime Use Building
Roof Area : 568 m2
Roof Insulation : Rigid Board 1 inch R = 2.1 m2·K/W
Wall Area : 1130 m2
Wall Insulation : Rigid Board 1 inch R = 1.41 m2·K/W
Total Fenestration Area: 508 m2
Window to Wall ratio : 508/1130 = 45%
East/West and South facing windows are all 1.82880m × 0.91440m with a 0.45720 m overhang and
represent 75% of the glazing on the building.
Projection Factor : H/V = 0.45720/1.82880 = 0.25
“M” factor : 0.79
(From ECBC Table 4.4, Projection Factor=0.25, E/W and S orientation for north latitude 15° or greater)
East/West and South facing glazing : 508 × 0.75 = 381 m2
East/West and South facing Fenestration : SHGC 0.20; U – factor 3.30
East/West and South Facing Fenestration: Skylight Area 10.8 m2

Building Envelope
Q: Does my building envelope comply Prescriptively with the ECBC?
A: To utilize the prescriptive requirements of ECBC, vertical fenestration is limited to 60% of the gross
wall area, so this building is allowed under this method.
ECBC Table 4.3 limits the SHGC value to a maximum of 0.20 for composite climate zone, however
an exception exists by use of an overhang. ECBC §4.3.3 allows for an “M” Factor, or multiplier. In
this case the M is 0.79.
Multiplying “M” times the SHGC [0.7900 × 0.20=0.1580] and thus complies with ECBC Table 4.3.
Exception to SHGC Requirements in §4.3.3: Vertical Fenestration areas located more than 2.2 m (7 ft) above the
level of the floor are exempt from the SHGC requirement in Table 4.3 if the following conditions are complied with:
Total Effective Aperture: The total Effective Aperture for the elevation is less than 0.25, including alla.
fenestration areas greater than 1.0 m (3 ft) above the floor level
An interior light shelf is provided at the bottom of this fenestration area, with an interior projectionb.
factor not less than:
1.0 for E-W, SE, SW, NE, and NW orientationsi.
0.5 for S orientation, andii.
0.35 for N orientation when latitude is < 23iii.
Minimum Visible Transmission of Glazing for Vertical Fenestration.4.3.4.1
ECBC encourages the use of daylighting features in buildings. Box 4-J discusses how glazing affect the
daylighting. It also explains the concept of Visual Light Transmittance (VLT) and Effective Aperture (EA) of
Glazing.
As per the Code:
Vertical fenestration product shall have the minimum Visual Light Transmittance (VLT), defined as function
of Window Wall Ratio (WWR), where Effective Aperture > 0.1, equal to or greater than the Minimum VLT
requirements of Table 4.5 (of ECBC).
: Minimum VLT Requirements (ECBC Table 4.5)Table 4.9
Window Wall Ratio Minimum VLT
0 - 0.3 0.27
0.31-0.4 0.20
0.41-0.5 0.16
0.51-0.6 0.13
: Daylighting, Visual Light Transmittance and Effective ApertureBox 4-J
Visual Light Transmittance (also known as Visual Transmittance VT) is defined as the ratio of light that passes
through the glazing to the light passing through perfectly transmitting glazing. In other words it also refers
to the fraction of visible light transmitted through the glazing. VLT is concerned with the visible portion of
the solar spectrum (See Figure 4.11) as opposed to SHGC, which takes into account the entire solar radiation.
VLT affects energy consumption in building by providing daylight that creates the opportunity to reduce
electric lighting and its associated cooling loads. Glazing with low SHGC generally has a low VLT; however,
if the VLT is too low, the outside view from inside the building will be impaired. With lower VLT, the
daylighting in the interior may also reduce to a level that may require supplemental electrical lighting for some
occupants’ functions, or to make the environment productive and enjoyable to the occupants. Thus buildings
with lower window to wall ratios (WWR), may need higher VLT.

Building Envelope
: Illustration to show U-factor, SHGC, and VLTFigure 4.11
Effective Aperture of Glazing
In simple terms, as the area of an aperture/opening in the building envelope increases, the amount of daylight
received in the building space also increases. However the glazing material within that aperture can effectively
reduce the amount of visible light that enters the space. Therefore, aperture size alone is not an effective
determinant to measure illumination levels. If the glazing in an opening is a perfectly transparent material the
effective aperture size would be equal to the area of the opening (because the visible transmittance of the
glazing would be one). If however, the glazing has a VLT of 0.5, the opening will transmit only half of the
light striking it, and the effective aperture will be half of the actual size of the opening.
The Effective Aperture (EA) or light admitting potential of a glazing system is determined by multiplying the
Visible Light Transmittance of the glazing by the window-to-wall ratio of the building. The window to wall
ratio is the ratio of the net window area to the exterior wall area.
Effective Aperture: Visible Light Transmittance × Window-to-Wall Ratio (WWR). = VLT × WWR.
Example: Two cases with WWR =0.4, and WWR = 0.6 are discussed below.
Case 1 Case 2
WWR = 0.4
VLT = 0.26
EA = 0.104 (EA > 0.1)
Glazing complies with ECBC
WWR = 0.6
VLT = 0.15
EA = 0.09 (EA < 0.1)
Glazing does not comply with ECBC
Skylights4.3.5
A skylight is a fenestration surface having a slope of less than 60 degrees from the horizontal plane. Other
fenestration, even if mounted on the roof of a building, is considered vertical fenestration.
Skylights can be installed into a roof system either flush-mounted or curb-mounted (including site built). In
order to create a positive water flow around them, skylights are often mounted on “curbs” set above the roof
plane. However, these curbs, rising 6 to 12 inches (15 to 30 centimeters) above the roof, create additional heat
loss surfaces right where the warmest air of the building tends to collect. Portions of roof that serve as curbs
that mount the skylight above the level of the roof (See below) are part of the opaque building envelope.

Building Envelope
: Skylight InstallationsFigure 4.12
As per the Code:
Skylights shall comply with the maximum U-factor and maximum SHGC requirements of Table 4.6. Skylight
area is limited to a maximum of 5% of the gross roof area for the prescriptive requirement.
: Skylight U-Factor and SHGC Requirements (ECBC Table 4.6)Table 4.10
Maximum U-factor Maximum SHGC
Climate With Curb w/o Curb 0-2% SRR 2.1-5% SRR
Composite 11.24 7.71 0.40 0.25
Hot and Dry 11.24 7.71 0.40 0.25
Warm and Humid 11.24 7.71 0.40 0.25
Moderate 11.24 7.71 0.61 0.4
Cold 11.24 7.71 0.61 0.4
SRR: Skylight roof ratio which is the ratio of the total skylight area of the roof, measured to the outside of
the frame, to the gross exterior roof. See §11.2.2 for typical complying skylight constructions.
: Prescriptive Requirements for SkylightsExample 4.3
Location : Chennai
Climate Zone : Warm-Humid
Building Type : Daytime Use Building
Roof Area : 1,863 m2
Roof Insulation : Rigid Board 1 inch R= 2.1 m2·°K/W
Wall Area : 3,706 m2
Wall Insulation : Rigid Board 1 inch R= 1.41 m2·°K/W
Fenestration Area : 487 m2
Window to Wall ratio : 487/3706 = 13%
SHGC : 0.20
U–factor : 3.30
Skylight Area : 112 m2
Skylight to Roof Area : 112/1863= 6%
Q: Does my building envelope comply with the ECBC using the prescriptive path?
A: No, this building does not comply because the prescriptive approach limits skylights area to a maxi-
mum of 5% of the roof area. This building would need to comply under the envelope trade off option
of the Whole Building Approach.
As with windows, the skylight-roof ratio must be calculated separately for each space category. The criteria for each
space category are determined from its own skylight-roof ratio, not the skylight-roof ratio for the whole building.

Building Envelope
: Glazing Selection for ECBC ComplianceBox 4-K
What is the most important feature that a building professional should look for regarding windows,
doors, and skylights?
The SHGC and U-factor ratings are the most important items to verify during inspections. Building
professionals should verify that the ratings of the installed windows, doors, and skylights meet or exceed the
ratings specified on the plans. It is also important to verify that the same window area has been installed as the
area shown on the plans and that the glass orientation on the plans and building are consistent.
What is Solar Heat Gain Coefficient?
The Solar Heat Gain Coefficient is a measure of the percentage of heat from the sun that gets through a
window or other fenestration product. The SHGC is expressed as a number between 0 and 1. The lower a
window’s SHGC, the less solar heat it transmits to the interior of the building. SHGC can also refer to shading
so the lower the SHGC the more effective the product is at shading the heat gain from entering the interior.
What is low-e glass?
Low-e stands for low-emissivity and refers to a special coating that reduces the heat transfer of a window
assembly. Low-e coated products that reduce solar heat gain can be produced by adding a metallic coating
either while the glass is in a molten state or by applying to the glass after it has cooled to a solid state. Low-e
glass is readily available from all the glass and window manufacturers. The coatings typically add about 10%
to the cost of a window but costs vary by product type, by manufacturer, by retailer and by location.
What is spectrally selective glass?
The sun emits visible solar radiation in the form of light and infrared radiation that cannot be seen, but
causes heat. Spectrally selective glass transmits a high proportion of the visible solar radiation, but screens
out radiant heat from the sun – significantly reducing the need to cool a building’s interior. Spectrally selective
glass is used to describe low-e coated glass that lowers the SHGC.
How can I be sure I have spectrally selective glass?
The SHGC rating for the product is the key to determining whether you have glass with a spectrally selective
coating. In general, windows with a spectrally selective low-e coating will have SHGC ratings of 0.40 or lower.
Building Envelope Trade-Off Option4.4
This is a systems-based approach, where the thermal performance of individual envelope components can be
reduced if compensated by higher efficiency in other building components (i.e., using higher wall insulation
could allow for a less stringent U-factor requirement for windows, or vice versa.) These trade-offs typically
occur within major building systems – roofs, walls, fenestration, overhangs etc.
This method offers the designer more flexibility than strictly following the prescribed values for individual
elements. The thermal performance of one envelope component such as the roof can fail to meet the prescriptive
requirements as long as other components perform better than what is required. Trade-offs are permitted
only between building envelope components. It is not possible, for instance, to make trade-offs against
improvements in the lighting or HVAC systems. However, this makes using the envelope trade-off option more
complicated than the prescriptive method. It is necessary to calculate the surface area of each exterior and semi-
exterior surface; all areas must also be calculated separately for each orientation. The equations used for calculating
envelope performance factor under envelope trade-offs are documented in ECBC §12 Appendix D.

Heating, Ventilation and Air Conditioning
Heating,Ventilation and Air Conditioning5.
General5.1
Heating, Ventilation and Air Conditioning (HVAC) refers to the equipment, distribution systems, and
terminals that provide, either collectively or individually, the heating, ventilation, or air-conditioning
requirement to a building or a portion of building. The HVAC system accounts for a significant portion
of a commercial building’s energy use. HVAC energy use in a commercial building can increase/decrease
significantly depending on how efficiently the combination of air side systems and central plant operates.
Proven technologies and design concepts can be used to build energy efficiencies in the system and generate
significant energy and cost savings.
HVAC systems also affect the health, comfort, and productivity of occupants. Issues like user discomfort,
improper ventilation, lack of air movement and poor indoor air quality, and poor acoustic design are linked to
HVAC system design and operation and can be improved. In many existing buildings, envelope upgrades are
often necessary to improve comfort and energy efficiency, through improvements such as reducing envelope
leakage. Generally, upgrading an existing building envelope is expensive. Other strategies such as central plant,
airside or control system upgrade may be necessary to improve occupant comfort and energy efficiency.
The best HVAC design considers all the interrelated building systems while addressing indoor air quality,
thermal comfort, energy consumption, and environmental benefits. Optimizing both the design and the benefits
requires that the architect and mechanical system designer address these issues early in the schematic design
phase and continually revise subsequent decisions throughout the remaining design process. It is also essential
that a process be implemented to monitor proper installation and operation of the HVAC system throughout
construction. An effective commissioning plan for each of the systems at full load and part load including
controls calibration and commissioning is essential to the optimal performance of the building.
General concepts of HVAC systems are discussed in more details in Box 5-A and Box 5-B.
Box 5-A: Air Conditioning System Basics
Basic components of the system include a compressor, condenser (air-cooled or water cooled), evaporator
and an expansion device., similar to that of a domestic refrigerator.
Discharge Line
Compressor
Suction Line
Evaporater
Condenser
Expansion Device
Liquid Line
A
B
C
D
Room air is drawn across an indoor coil called the evaporator that cools and dehumidifies the air during the
cooling cycle. The condenser condenses the refrigerant and transforms the high pressure vapor into high
pressure liquid. Heat is rejected via air drawn across the condenser coils using fans (air-cooled condenser) or
using a shell and tube heat exchanger in conjunction with a condenser water reticulation system and cooling
towers (water cooled condenser). The expansion device transforms the high pressure high temperature
liquid refrigerant to low pressure low temperature mixture of refrigerant liquid and vapor. This mixture fully
evaporates in the evaporator absorbing the heat from the water (cooling the water in a chilled water system)
or cooling the air drawn across the coil (direct expansion system). The compressor then raises the pressure
and temperature of the refrigerant and the cycle continues on.

: Heating SystemsBox 5-B
Heating system types can be classified fairly well by the heating equipment type. The heating equipment used
in buildings includes boilers (oil and gas), furnaces (oil, gas, and electric), heat pumps, and space heaters.
Boiler-based heating systems have steam and/or water piping to distribute heat. Boilers can be self-contained
units, or they can be packaged units which are factory-built systems, disassembled for shipment, and
reassembled at the site. The heated water may serve preheat coils in air handling units; reheat coils, and
local radiators. Systems that circulate water or a fluid are called hydronic systems. Heating water may also
be used for heating of service water and other process needs, depending on the building type. Some central
systems have steam boilers rather than hot water boilers because of the need for steam for conditioning
needs (humidifiers in air-handling units) or process needs (sterilizers in hospitals, direct-injection heating in
laundries and dishwashers, etc.). The remaining heating systems include heat pumps and space heaters that
heat directly and require little or no distribution.
The Code contains mandatory requirements for the following elements of the HVAC system:
Natural Ventilation•
Equipment Efficiency •
Controls•
Piping and Ductwork•
System Balancing.•
Condensers•
Economizers•
Hydronic Systems•
Natural Ventilation5.2.1
As per the Code:
Natural ventilation (of buildings) shall comply with the design guidelines provided for natural ventilation in the
National Building Code of India 2005,(NBC, 2005) Part 8, 5.4.3 and 5.7.1
These guidelines from NBC, 2005 have been reproduced below in Box 5-C, keeping in view the philosophy
behind this Guide to include ECBC-referenced material in the Guide. However, the exact relevance of these
general guidelines in the design of commercial buildings need to be critically examined.
Box 5-C: Design Guidelines for Natural Ventilation
By Wind Action
Building need not necessarily be oriented perpendicular to the prevailing outdoor wind; it may bei.
oriented at any convenient angle between 0° and 30° without losing any beneficial aspect of the
breeze. If the prevailing wind is from east or west, building may be oriented at 45° to the incident
wind so as to diminish the solar heat without much reduction in air motion indoors.
Inlet openings in the buildings should be well distributed and should be located on the windwardii.
side at a low level, and outlet openings should be located on the leeward side. Inlet and outlet
openings at high levels may only clear the top air at that level without producing air movement at
the level of occupancy.
Maximum air movement at a particular plane is achieved by keeping the sill height of the openingiii.
at 85% of the critical height (such as head level) for the following recommended levels of
occupancy:
For sitting on chair 0.75 m1.
For sitting on bed 0.60 m2.

For sitting on floor 0.40 m3.
Inlet openings should not, as far as possible, be obstructed by adjoining buildings, trees, signiv.
boards or other obstructions or by partitions inside in the path of air flow.
In rooms of normal size having identical windows on opposite walls the average indoor air speedv.
increases rapidly by increasing the width of the window up to two-thirds of the wall width; beyond
that the increase is in much smaller proportion than the increase of the window width. The air
motion in the working zone is maximum when window height is 1.1 m. Further increase in window
height promotes air motion at higher level of window, but does not contribute additional benefits
as regards air motion in the occupancy zones in buildings.
Greatest flow per unit area of openings is obtained by using inlet and outlet openings of nearby equal areasvi.
at the same level.
For a total area of openings (inlet and outlet) of 20% to 30% of floor area, the average indoorvii.
wind velocity is around 30% of outdoor velocity. Further increase in window size increases the
available velocity but not in the same proportion. In fact, even under most favorable conditions the
maximum average indoor wind speed does not exceed 40% of outdoor velocity.
Where the direction of wind is quite constant and dependable, the size of the inlet should be keptviii.
within 30 to 50% of the total area of openings and the building should be oriented perpendicular
to the incident wind. Where direction of the wind is quite variable, the openings may be arranged
so that as far as possible there is approximately equal area on all sides. Thus no matter what the
wind direction is, there would be some openings directly exposed to wind pressure and others to
air suction and effective air movement through the building would be assured.
Windows of living rooms should open directly to an open space. In places where building sites areix.
restricted, open space may have to be created in the buildings by providing adequate courtyards.
In the case of rooms with only one wall exposed to outside, provision of two windows on that wallx.
is preferred to that of a single window.
Windows located diagonally opposite to each other with the windward window near the upstreamxi.
comer give better performance than other window arrangements for most of the building
orientations.
Horizontal louvers, that is a sunshade, atop a window deflects the incident wind upward andxii.
reduces air motion in the zone of occupancy. A horizontal slot between the wall and horizontal
louver prevents upward deflection of air in the interior of rooms. Provision of inverted L type (r)
louver increases the room air motion provided that the vertical projection does not obstruct the
incident wind.
Provision of horizontal sashes inclined at an angle of 45° in appropriate direction helps to promotexiii.
the indoor air motion. Sashes projecting outward are more effective than projecting inward.
Air motion at working plane 0.4 m above the floor can be enhanced by 30% using a pelmet typexiv.
wind deflector.
Roof overhangs help by promoting air motion in the working zone inside buildings.xv.
Verandah open on three sides is to be preferred since it causes an increase in the room air motionxvi.
for most of the orientations of the building with respect to the outdoor wind.
A partition placed parallel to the incident wind has little influence on the pattern of the air flow, butxvii.
when located perpendicular to the main flow, the same partition creates a wind shadow. Provision
of a partition with spacing of 0.3 m underneath helps by augmenting air motion near floor level in
the leeward compartment of wide span buildings.
Air motion in a building unit having windows tangential to the incident wind is accelerated whenxviii.
unit is located at end-on position on downstream side.
Air motion in two wings oriented parallel to the prevailing breeze is promoted by connecting themxix.
with a block on downstream side.
Air motion in a building is not affected by constructing another building of equal or smaller heightxx.
on the leeward side; but it is slightly reduced if the leeward building is taller than the windward
block.

Air motion in a shielded building is less than that in an unobstructed building. To minimize thexxi.
shielding effect, the distances between two rows should be 8H for semi-detached houses and
10H for long rows houses. However, for smaller spacing the shielding effect is also diminished by
raising the height of the shielded building.
Hedges and shrubs deflect the air away from the inlet openings and cause a reduction in indoorxxii.
air motion. These elements should not be planted at a distance of about 8m from the building
because the induced air motion is reduced to minimum in that case. However, air motion in the
leeward part of the building can be enhanced by planting a low hedge at a distance of 2m from
the building.
Trees with large foliage mass having trunk bare of branches up to the top level of window, deflectxxiii.
the outdoor wind downwards and promotes air motion in the leeward portion of buildings.
Ventilation conditions indoors can be ameliorated by constructing buildings on earth moundxxiv.
having a slant surface with a slope of 10° on the upstream side.
In case of industrial buildings the window height should be about 1.6m and the width about two-xxv.
thirds of wall width. These should be located at a height of 1.1m above the floor. In addition,
openings around 0.9m high should be provided over two-thirds of the length of the glazed area
in the roof lights.
Height of industrial buildings, although determined by the requirements of industrial processesxxvi.
involved, generally kept large enough to protect the workers against hot stagnant air below the
ceiling as also to dilute the concentration of contaminant inside. However, if high level openings
in roof or walls are provided, building height can be reduced to 4m without in any way impairing
the ventilation performance.
By Stack Effect
Natural ventilation by stack effect occurs when air inside a building is at a different temperature than air
outside. Thus, in heated buildings or in buildings wherein hot processes are carried out and in ordinary
buildings during summer nights and during premonsoon periods, when the inside temperature is higher than
that of outside, cool outside air will tend to enter through openings at low level and warm air will tend to
leave through openings at high level. It would, therefore, be advantageous to provide ventilators as close to
ceilings as possible. Ventilators can also be provided in roofs as, for example, cowl, ventpipe, covered roof
and ridge vent.
Energy Conservation in Ventilation System
Maximum possible use should be made of wind-induced natural ventilation. This may be accom-
plished by following the design guidelines
Adequate number of circulating fans should be installed to serve all interior working areas duringi.
the summer months in the hot dry and warm humid regions to provide necessary air movement at
times when ventilation due to wind action alone does not afford sufficient relief.
The capacity of a ceiling fan to meet the requirement of a room with the longer dimension Dii.
meters should be about 55D m3/min.
The height of fan blades above the floor should be (3H + W)/4, where H is the height of theiii.
room, and W is the height of the work plane.
The minimum distance between fan blades and the ceiling should be about 0.3 meters.iv.
Electronic regulators should be used instead of resistance type regulators for controlling the speedv.
of fans.
When actual ventilated zone does not cover the entire room area, then optimum size of ceiling fanvi.
should be chosen based on the actual usable area of room, rather than the total floor area of the
room. Thus smaller size of fan can be employed and energy saving could be achieved.
Power consumption by larger fans is obviously higher, but their power consumption per squarevii.
meter of floor area is less and service value higher. Evidently, improper use of fans irrespective
of the rooms dimensions is likely to result in higher power consumption. From the point of
view of energy consumption, the number of fans and the optimum sizes for rooms of different
dimensions are given in the following table:

: Optimum Size/Number of Fans for Rooms of Different SizesTable 5.1
Room
Width
Room Length
m 4m 5m 6m 7m 8m 9m 10m 11m 12m 14m 16m
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12)
3 1200/1 1400/1 1500/1 1050/2 1200/2 1400/2 1400/2 1400/2 1200/3 1400/3 1400/3
4 1200/1 1400/1 1200/2 1200/2 1200/2 1400/2 1400/2 1500/2 1200/3 1400/3 1500/3
5 1400/1 1400/1 1400/2 1400/2 1400/2 1400/2 1400/2 1500/2 1400/3 1400/3 1 500/3
6 1200/2 1400/2 900/4 1050/4 1200/4 1400/4 1400/4 1500/4 1200/6 1400/6 1 500/6
7 1200/2 1400/2 1050/4 1050/4 1200/4 1400/4 1400/4 1500/4 1200/6 1400/6 1 500/6
8 1200/2 1400/2 1200/4 1200/4 1200/4 1400/4 1400/4 1500/4 1200/6 1400/6 1 500/6
9 1400/2 1400/2 1400/4 1400/4 1400/4 1400/4 1400/4 1500/4 1400/6 1400/6 1500/6
10 1400/2 1400/2 1400/4 1400/4 1400/4 1400/4 1400/4 1500/4 1400/6 1400/6 1 500/6
11 1500/2 1500/2 1500/4 1500/4 1500/4 1500/4 1500/4 1500/4 1500/6 1500/6 1 500/6
12 1200/3 1400/3 1200/6 1200/6 1200/6 1400/6 1400/6 1500/6 1200n 1400/9 1400/9
13 1400/3 1400/3 1200/6 1200/6 1200/6 1400/6 1400/6 1500/6 1400/9 1400/9 1 500/9
14 1400/3 1400/3 1400/6 1400/6 1400/6 1400/6 1400/6 1500/6 1400/9 1400/9 1500/9
Source: National Building Code of India 2005.
For data on outdoor wind speeds at a place, reference may be made to “The Climatic Data Handbook prepared
by Central Building Research Institute, Roorkee, 1999.” Box 5-D provides additional information in naturally
ventilated spaces for tropical countries.
: Optional Method for Determining Acceptable Thermal Conditions inBox 5-D
Naturally Conditioned Spaces Based on Field Experiments Conducted in Tropical
Countries
The adaptive model of thermal comfort is derived from a global database of 21,000 measurements taken
primarily in office buildings in the tropical climate. The allowable operative temperature limits may not be
extrapolated to the outdoor temperature above and below the end points of the curves in this figure. If the
mean monthly outdoor temperature is less than 10°C or greater than 33.5°C, this option may not be used.
Occupant-controlled naturally conditioned spaces are those spaces where the thermal conditions of the space
are regulated primarily by the occupants through opening and closing of windows. Field experiments have
shown that occupants’ thermal responses in such spaces depend in part on the outdoor climate and may
differ from thermal responses in buildings with centralized HVAC systems primarily because of the different
thermal experiences, changes in clothing, availability of control, and shifts in occupant expectations. This
optional method is intended for such spaces.
In order for this optional method to apply, the space must be equipped with operable windows that open
to the outdoor and that can be readily opened and adjusted by the occupants of the space. Mechanical
ventilation with unconditioned air may be utilized, but opening and closing of windows must be the primary
means of regulating the thermal conditions in the space. The space may be provided with a heating system,
but this optional method does not apply when a heating system is in operation. It applies only to spaces where
the occupants are engaged in near sedentary physical activities, with metabolic rates ranging from 1.0 met to
1.3 met1. This optional method applies only to spaces where the occupants may freely adapt their clothing to
the indoor and/or outdoor thermal conditions.
Limits on Temperature Drifts and Ramps
Time Period 0.25h 0.5h 1h 2h 4h
Maximum Operative
Temperature Change Allowed
1.1° C (2.0°F) 1.7°C (3.0°F) 2.2°C (4.0°F) 2.8°C (5.0°F) 3.3°C (6.0°F)

: Acceptable operative temperature ranges for naturally conditioned spaces.Figure 5.1
Allowable indoor operative temperature for spaces that meet these criteria may be determined from the figure
above. This figure includes two sets of operative temperature limits —one for 80% acceptability and one for 90%
acceptability. The 90% acceptability limits may be used when a higher standard of thermal comfort is desired.
1 1met= 58W/m2 : for typical office activity, one person is likely to produce 100- 125 watts of heat.
Source: ASHRAE 55, 2004.
Minimum Equipment Efficiencies5.2.2
Minimum equipment efficiencies are required to be met for all HVAC equipment. These include chillers, unitary
air conditioner, split air conditioner, packaged air conditioner, and boilers. Box 5-E and Box 5-F provide basic
information and an overview of air conditioning systems. Box 5-G provides more information on Chillers.
: Type of Air-Conditioning SystemsBox 5-E
There are primarily two main types of air conditioning systems:
A direct expansion or “DX” type system in the form of room air conditioners, split system air1.
conditioners and packaged air conditioners. Heat exchange takes place directly from the refrigerant
within the copper tubes to the air being drawn across the finned coil by an evaporator fan. The DX
type systems offer localized solutions for a building’s heating and cooling needs. These systems are
typically appropriate for smaller (single-zone) buildings.
Central plant system uses chilled water recirculation. Compared to a DX systems, a central plant2.
HVAC will be able to provide better thermal comfort and flexibility.
Direct Expansion Systems or DX Systems
Unitary air conditioners: These are normally used for cooling individual rooms and provide cooling only
when needed. Room air conditioners house all the components of an air conditioning system discussed above
in one casing. Their efficiency is generally lower than that of central plant systems.
Split-system air conditioning systems: This consists of an outdoor metal cabinet that contains the
condenser and compressor, and an indoor cabinet that contains the evaporator. In many split-system air
conditioners, this indoor cabinet also contains a furnace or the indoor part of a heat pump.
Packaged air conditioners: In a packaged air conditioner, the evaporator, condenser, and compressor are
all located in one cabinet, which usually is placed on a roof or on a concrete slab adjacent to the building. This
type of air conditioner is typical in small commercial buildings and also in residential buildings. Air supply and
return ducts come from indoors through the building’s exterior wall or roof to connect with the packaged
air conditioner, which is usually located outdoors. Packaged air conditioners often include electric heating
coils or a natural gas furnace. This combination of air conditioner and central heater eliminates the need for
a separate furnace indoors.

Central Plant Systems
Central plant air conditioning systems: In central air-conditioning systems, chilled water is generated via
a central chilled water plant. The chilled water is distributed to air-handling units or fan-coil units via a chilled
water reticulation system consisting of chilled water pipes, valves, fittings, and pumps. The chillers used in
central chilled water plants include air-cooled chillers as well as water-cooled chiller systems that work in
conjunction with cooling towers for heat rejection.
Box 5-F provides an overview of the differences between DX and Central HVAC systems. It should help in
selecting appropriate system for the building.
: Overview of DX and Central Plant HVAC SystemsBox 5-F
Central Chilled Water Systems Direct Expansion or “DX” Systems
Building Space
Requirements
Will require separate building space to house the chillers,
boilers, pumps, AHU’s, distribution networks and control
panels. In addition, space is required outdoors for
condensing unit for air-cooled machines and cooling tower
for water-cooled machines.
The building structure should be designed to take the
weight of equipment. Suitable vibration control must be
considered and adequate load bearing beams and columns
must be available for lifting and shifting of such equipment.
No separate plant room space is required as the
refrigeration package is integral to the package
unit/condensing unit which is generally located
outdoors. Evaporator units are generally located
indoors.
The local systems are smaller in size and are less
bulky.
Aesthetics Central systems are generally designed as concealed systems
and the visible distribution grilles etc. can be easily blended
with the aesthetics.
The appearance of local units can be
unappealing and may not necessarily blend well
with the aesthetics.
Zoning Central HVAC system may serve multiple thermal zones
and have their major components located outside the
zone(s) being served, usually in some convenient central
location. This system can provide better flexibility in terms
of zoning.
A local HVAC system typically serves a single
thermal zone and has its major components
located within the zone itself or directly adjacent
to the zone. Multiple units are required for
multiple zones. This system is less flexible to
zoning requirements.
Air Quality The quality of air conditioning is comparatively superior,
with better control over temperature, relative humidity, air
filtration, and air distribution.
Best suited for applications demanding close control of
temperature, humidity, and cleanliness and can be customized
as per the design conditions.
The air quality is not comparable to central
systems. These systems typically cannot provide
close humidity control or high efficiency
filtration.
The compact systems, being standard factory
items, typically cannot be modified to suit the
required design conditions all the times.
Controls Central HVAC systems will require a control point for each
thermal zone. The controls are field wired and are integrated
to a central control panel. The controls are complex and
depend on the type of system.
Constant air volume (CAV) systems alter the temperature
while keeping the constant air delivery. CAV systems
serving multiple zones rely on reheat coils to control the
delivered cooling. This incurs a lot of energy wastage due to
simultaneous cooling and heating.
Space temperature control can also be achieved by applying
a variable air volume (VAV) system, which primarily alters
the air delivery rates. The VAV system may or may not have
a reheat coil, which provides additional heat when the space
does not need to be cooled or needs less cooling than would
be delivered by supply air at the terminal box’s minimum air
quantity setting.
Proper zoning using “face zoned” AHUs working in
conjunction with downstream VAV boxes will provide
energy-efficient cooling and eliminate the need of reheat.
Local units are off-shelf items complete
with integrated controls. They usually have a
single control point which is typically only a
thermostat.
The room-by-room or “zone” control minimizes
over cooling typical of central air-conditioning
systems. With the zone-control ability of the
compact systems, only occupied spaces are
maintained at a comfort level, and conditioning
for the rest of the building is turned down or
shut off.
It should be noted that some DX systems have
limitedcapacitycontrolandhavelimitedcapability
to reduce airflow during low load situations.
Hence, there is a limitation in saving fan energy
in DX systems with some types of DX systems
only having on/off control for the compressors
that can result in considerable hunting and space
temperature fluctuation.

Efficiency Central systems usually operate under part load conditions,
and localized areas cannot be isolated for complete shut
down under any condition.
In a central system, the individual control option is not
always available. If individual control is desired, the system
shall be designed as variable air volume system with localized
thermostats.
Central systems designed for VAV system is based on block
load calculations, as the VAV units allow the system to
borrow air from areas with low load. By incorporating VAVs
with variable speed drive on air handling units, it is possible
to achieve excellent savings in power.
Proper zoning as mentioned earlier can avoid conflicting
demands for heating and cooling.
In a building where a large number of spaces
may be unoccupied at any given time, such as a
dormitory or a motel, local systems may be totally
shut off in the unused spaces, thus providing
huge energy saving potential.
As a self-contained system, a local HVAC system
may provide greater occupant comfort through
totally individualized control options -- if one
room needs heating while an adjacent one needs
cooling, two local systems can respond without
conflict
As the compact systems are small, they are
designed for full peak load and the standard
rooftop or package units are not typically
available with variable speed option. This type
of system therefore has very limited potential
to operate efficiently during part load situations.
The availability of VRF system is changing this.
Refrigerant
Containment
Central plant systems provide an excellent means to contain
all refrigerant within the chiller housing and plant room. It is
possible to detect any minor leaks within the localized plant
room and take remedial action to arrest the leak.
Unlike central systems, DX systems pose a greater
risk of refrigerant leaks to the atmosphere. With
DX systems installed in several localized areas it
may be very difficult or impossible to detect these
leaks, especially in split systems with long pipe
runs using high pressure refrigerant.
Operations
and
Maintenance
(O&M)
Large central systems can have a life useful life of up to 25
years.
Central systems allow major equipment components to be
kept isolated in a mechanical room. Grouping and isolating
key operating components allows maintenance to occur with
limited disruption to building functions.
Local systems can have a useful life of up to 15
years.
Local systems maintenance may often be
relatively simple but maintenance may have to
occur directly in occupied spaces.
Cost The initial purchasing and installation cost of a central air
conditioning system is much higher than a local system.
These systems can offer higher system efficiencies (full load
and part load) and thus, can pay pack the elevated initial
costs through reduced costs of operations within a few
years.
Extra cost benefits can be achieved due to the potential
for energy efficiency measures like thermal heat recovery,
economizers, energy storage systems and etc.
Packaged and split units have much lower first
costs than a central system.
The operating costs of unitary systems is usually
higher due to lower efficiency ratings and lower
part load performance values
The potential for adoption of high-tech energy
efficiency measures is very limited
Source: A. Bhatia, Course Content (PDH 149), HVAC Design Aspects: Choosing A Right System-Central
V/s Compact Systems. http://www.pdhcenter.com/Heating System Types, and Team Catalyst
The Code refers to various types of chillers; Box 5-G gives a brief description of the chillers.
: ChillerBox 5-G
What is a Chiller?
A chiller is essentially a packaged vapor compression cooling machine. The chiller rejects heat either to
condenser water (in the case of a water-cooled chiller) or to ambient air (in the case of an air-cooled chiller).
Water-cooled chillers incorporate the use of cooling towers, which improve heat rejection more efficiently
at the condenser than air-cooled chillers. For a water-cooled chiller, the cooling tower rejects heat to the
environment through direct heat exchange between the condenser water and cooling air. For an air-cooled
chiller, condenser fans move air through a condenser coil. As heat loads increase, water-cooled chillers are
more energy-efficient than air-cooled chillers. A typical chiller is rated between 15 to 1000 tons (53 to 3,500
kW) in cooling power.

What are the different types of chillers?
Chillers are classified according to compressor type. Electric chillers for commercial comfort cooling have
centrifugal, screw, scroll, or reciprocating compressors. Centrifugal and screw chillers have one or two
compressors. Scroll and reciprocating chillers are built with multiple, smaller compressors.
Centrifugal chillers are the quiet, efficient, and reliable workhorses of comfort cooling. Although•
centrifugal chillers are available as small as 70 tons, most are 300 tons or larger.
Screw chillers are up to 40% smaller and lighter than centrifugal chillers, so are becoming popular•
as replacement chillers.
Scroll compressors are rotary positive-displacement machines, also fairly new to the comfort cool-•
ing market. These small compressors are efficient, quiet, and reliable. Scroll compressors are made
in sizes of 1.5 to 15 tons.
The energy efficiency of cooling and heating systems in terms of Coefficient of Performance (COP), Energy
Efficiency Ratio (EER) and Integrated Part-Load Value as specified by the Code are presented in Box 5-H
: Energy Efficiency TermsBox 5-H
Coefficient of Performance (COP) – Cooling
The ratio of the rate of heat removal to the rate of energy input, in consistent units, for a complete refrigerating
system or some specific portion of that system under designated operating conditions
Coefficient of Performance (COP) – Heating
The ratio of the rate of heat delivered to the rate of energy input, in consistent units, for a complete heat pump
system, including the compressor and, if applicable, auxiliary heat, under designated operating conditions
Energy Efficiency Ratio (EER)
The ratio of net cooling capacity in BTU/hr to total rate of electric input in watts under designated operating
conditions.
Integrated Part-Load Value (IPLV)
A single number figure of merit based on part-load EER, COP, or KW/ton expressing part-load
efficiency for air-conditioning and heat pump equipment on the basis of weighted operation at various
load capacities for the equipment.
As per the Code:
Cooling equipment shall meet or exceed the minimum efficiency requirements presented in Table 5.2. Heating
and cooling equipment not listed here shall comply with ASHRAE 90.1-2004 §6.4.1.
: ChillersTable 5.2
Equipment Class Minimum COP Minimum IPLV Test Standard
Air Cooled Chiller <530 kW (<150 tons) 2.90 3.16 ARI 550/590-1998
Air Cooled Chiller ≥530 kW (≥150 tons) 3.05 3.32 ARI 550/590-1998
*Centrifugal Water Cooled Chiller < 530 kW (<150
tons)
5.80 6.09 ARI 550/590-1998
*Centrifugal Water Cooled Chiller ≥530 and <1050
kW (≥150 and <300 tons)
5.80 6.17 ARI 550/590-1998
*Centrifugal Water Cooled Chiller ≥ 1050 kW (≥
300 tons)
6.30 6.61 ARI 550/590-1998
Reciprocating Compressor, Water Cooled Chiller
all sizes
4.20 5.05 ARI 550/590-1998
Rotary Screw and Scroll Compressor, Water
Cooled Chiller <530 kW (<150 tons)
4.70 5.49 ARI 550/590-1998

Cooled Chiller ≥530 and <1050 kW (≥150 and
<300 tons)
5.40 6.17 ARI 550/590-1998
Cooled Chiller ≥ 1050 kW (≥ 300 tons)
5.75 6.43 ARI 550/590-1998
*These are aspirational values. For mandatory values refer to ASHRAE 90.1-2004
As per the Code:
Unitary Air Conditioner shall meet IS 1391- Part 1 (Table 5.3), split air conditioner shall meet IS 1391 - Part 2
(Table 5.3), packaged air conditioner shall meet IS 8148 (Table 5.4) and boilers shall meet IS 13980 (the standard
specifies the procedure with above 75% thermal efficiency.
Table 5.3: Power Consumption Ratings for
Unitary Air Conditioners – Under Test Conditions
Rated Cooling Capacity Maximum Power
(kcal/h) kW Consumption (kW)
1,500 1.7 1.1
2,250 2.6 1.4
3,000 3.5 1.6
3,750 4.4 2.0
4,500 5.2 2.4
6,000 7.0 3.2
7,500 8.7 4.25
9,000 10.5 5.2
Table 5.4: Power Consumption Ratings for Split
Air Conditioners – Under Test Conditions
Rated Cooling Capacity Maximum Power
(kcal/h) kW Consumption (kW)
3 000 3.5 1.7
4 500 5.2 2.6
6 000 7.0 3.4
7 500 8.7 4.5
9 000 10.5 5.4
Source: Code No.: IS 1391 (Part-1): 1992
(amendment No. 2 Dec.2006 )
Source: Code No.: IS 1319 (Part-2): 1992
(amendment No. 2 Dec.2006)
Table 5.5: Power Consumption Rating for Packaged air Conditioners-under test conditions
Cooling Capacity Maximum Power Consumption in Watts
Watts Tons of Refrigeration Water Cooled Air Cooled
10,000 3 3,750 4,750
17,500 5 6,000 7,000
26,250 7.5 9,000 10,000
35,000 10 11,500 13,500
52,000 15 17,000 20,000
Source: Code No.: IS 8148: 2003
Selection of individual equipment efficiency should be considered in the context of the whole HVAC system.
In a chilled-water system, for example, although the chiller is at the core of the system and typically is the
single largest energy user, simply selecting a high-efficiency chiller does not guarantee high performance.
Auxiliary equipment (such as fans and blowers) and design decisions (such as “approach temperatures”) can
have substantial effects on overall efficiency. Thus, attention to overall system design and auxiliary components
is critical to achieving optimal performance and comfort. Even in packaged air-conditioning systems, leaky
ductwork, improper sizing, refrigerant charge, and air flow rates can considerably affect energy performance.
Controls5.2.3
Controls are one of the most critical elements for improving efficiency of any HVAC system. Controls determine
how HVAC systems should operate to meet the design goals of comfort, efficiency, and cost-effective operation.
In this context, the Code specifies the use of time clocks, temperature controls/thermostats, and two-speed or
variable speed drives for fans.

Timeclock Control5.2.3.1
As per the Code,
All mechanical cooling and heating systems shall be controlled by a timeclock that:
Can start and stop the system under different schedules for three different day-types per weeka.
Is capable of retaining programming and time setting during loss of power for a period of at leastb.
10 hours, and
Includes an accessible manual override that allows temporary operation of the system for up to 2c.
hours
Exceptions to the above are:
Cooling systems < 28 kW (8 tons)a.
Heating systems < 7 kW (2 tons)b.
Temperature Control5.2.3.2
As per the Code:
All heating and cooling equipment shall be temperature controlled. Where a unit provides both heating and
cooling, controls shall be capable of providing a temperature dead band of 3°C (5°F) within which the supply
of heating and cooling energy to the zone is shut off or reduced to a minimum. Where separate heating and
cooling equipment serve the same temperature zone, thermostats shall be interlocked to prevent simultaneous
heating and cooling.
It is important to clearly establish design conditions and ensure adequate dead band between cooling and
heating set points to avoid conflicting thermostat control conditions. Increasing the dead band can make the
system more stable and efficient.
Controls for Cooling Towers and Closed Circuit Fluid Coolers5.2.3.3
As per the Code:
All cooling towers and closed circuit fluid coolers shall have either two speed motors, pony motors, or variable
speed drives controlling the fans.
Box 5-I briefly discusses the concept of Variable Speed Drive, and Box 5-J provides guidelines for improving
energy and water efficiency in cooling towers.
Box 5-I: Variable Speed Drive
Avariablespeeddrive(VSD)isanelectronicdevicethatcontrolstherotationalspeedof apieceof motor-driven
equipment (e.g. a blower, compressor, fan, or pump). Speed control is obtained by adjusting the frequency of
the voltage applied to the motor. This approach usually saves energy for varying-load applications.
Through the application of VSD on the cooling tower fan, the fan speed can be reduced during lower ambient
conditions for reducing energy consumption. However condenser water reset strategy may require condenser
fan speeds to be maintained to improve chiller efficiency by lowering condenser water temperature. At lower
loads the overall system efficiency should be the driver as pumping and tower fan energy form significant
proportion of overall chiller plant energy.

: Energy and Water Efficiency in Cooling TowersBox 5-J
Energy and Water Efficiency in Cooling Towers
Water-based HVAC systems offer significant energy savings due to the ability of water to transport large
quantities of heat over relatively long distances, more efficiently than air-based systems. Additionally, they offer
advantages such as smaller equipment size and cost, along with reduced maintenance and extended life of
mechanical equipment. However, for water scarce urban centers in India, the viable installation and operation
of cooling towers will require balancing needs for energy efficiency and water conservation simultaneously. Air-
cooled chillers are a good option to conserve water, however the trade-off is that these chillers consume more
energy to provide the same amount of cooling when compared to water cooled machines with cooling towers.
Energy Efficiency Measures:
Proper site selection and sizing of the tower can reduce fan speed, capacity, and sound and help to•
conserve energy
Centrifugal fans in favor of lower energy axial fans can reduce horsepower by 50% or more for•
the same capacity
Fan control through two-speed motors, pony motors, or variable speed motors can save energy as well•
Water Efficiency Measures:
An optimized bleed rate for the tower should be maintained to regulate water consumption. The•
evaporation rate is dependent on the load, which can vary widely and a constant bleed rate usually
discharges more water than required. A properly operating conductivity meter can automatically control
bleed to the proper amount required to maintain the desired tower chemistry in the system at all times.
Contaminant induction should be minimized and a proper blow down rate should be maintained.•
Water treatment regimens are effective for water conservation, keeping the cooling loop cleaner,
saving energy, reducing maintenance, and improving reliability of the entire cooling system.
New technological solutions like hybrid wet-dry cooling tower designs, which combine wet and•
dry cooling can be adopted to reduce water use, some as much as 70% compared to conventional
towers. Typically, a dry finned coil section is combined in series with an evaporative section in these
units. The dry finned section handles as much of the load as possible, with the unit able to operate
completely dry at reduced ambient. Both open and closed circuit versions are available.
Source: Morrison F.: What’s up with Cooling Tower (2004). ASHRAE Journal 46 (7)
Piping and Ductwork5.2.4
Pipe Insulation5.2.4.1
To minimize heat losses, the Code requires that piping of heating and cooling systems, (including the storage
tanks,) must be insulated. The Code specifies required R-values of insulation for heating and cooling systems
based on the operating temperature of the system. These are as shown in Table 5.6 and Table 5.7.
: Insulation of Heating SystemsTable 5.6
Heating System
Designed Operating
Temperature of Piping
Insulation with
Minimun R-value
(m2·K/W)
60°C and above 0.74
Above 40°C and below 60°C 0.35
: Insulation of Cooling SystemsTable 5.7
Cooling System
Designed Operating
Temperature of Piping
Insulation with Minimun
R-value (m2·K/W)
Below 15°C 0.35
Refrigerant Suction Piping
Split System 0.35
As per the Code:
Insulation exposed to weather shall be protected by aluminum sheet metal, painted canvas, or plastic cover.
Cellular foam insulation shall be protected as above, or be painted with water retardant paint.

Ductwork5.2.4.2
As per the Code:
Ductwork shall be insulated in accordance with the Table 5.8.
: Ductwork InsulationTable 5.8
Required Insulationa (R-values in m2·K/W)
Duct Location Supply Ducts Return Ducts
Exterior R-1.4 R- 0.6
Ventilated Attic R-1.4 R- 0.6
Unventilated Attic without Roof Insulation R-1.4 R- 0.6
Unventilated Attic with Roof Insulation R- 0.6 No Requirement
Unconditioned Spaceb R- 0.6 No Requirement
Indirectly Conditioned Spacec No Requirement No Requirement
Buried R- 0.6 No Requirement
aInsulation R-value is measured on a horizontal plane in accordance with ASTM C518 at a mean temperature of 24°C
(75°F) at the installed thickness
bIncludes crawlspaces, both ventilated and non-ventilated
cIncludes return air plenums with or without exposed roofs above.
Table 5.9 provides R-value of a few insulating materials.
: Sample R-values for Duct Insulation MaterialsTable 5.9
Installed R-value1
(m2·K/W)
Typical Material Meeting or Exceeding the Given R-value2
1.9 ½ in. Mineral fiber duct liner per ASTM C 1071, Type 1
1 in. Mineral fiber duct wrap per ASTM C 1290
3.5 1 in. Mineral fiber duct liner per ASTM C 1071, Types I & II
1 in. Mineral fiber board per ASTM C 612, Types IA & IB
1 in. Mineral fiber duct board per UL 181
1 ½ in. Mineral fiber duct wrap per ASTM C 1290
1 in. Insulated flex duct per UL 181
6.0 1 ½ in. Mineral fiber duct liner per ASTM C1071, Types I & II
1 ½ in. Mineral fiber duct board per UL 181
1 ½ in. Mineral fiber board per ASTM C 612, Types IA & IB
2 in.. 2 lb/ft3 Mineral fiber duct wrap per ASTM C 1290
2 ½ in. 0.6 to 1 lb./ft3 Mineral fiber duct wrap per ASTM C 1290
2 ½ in. Insulated flex duct per UL 181
8.0 2 in. Mineral fiber duct liner per ASTM C 1071, Types I & II
2 in. Mineral fiber duct board per UL 181
2 in. Mineral fiber board per ASTM C 612, Types IA & IB
3 in. ¾ lb/ft3 Mineral fiber duct wrap insulation per ASTM C 1290
3 in. Insulated flex duct per UL 181
10.0 2 ½ in. Mineral fiber board per ASTM C 612, Types IA & IB
1 Listed R-values are for the insulation only as determined in accordance with ASTM C 518 at a mean temperature of 24°C at the
installed thickness and do not include air film resistance.
2 Consult with manufacturers for other materials or combinations of insulation thickness or density meeting the required R-value.
Source: ASHRAE 90.1 User Manual (2007), Table 6-D

Ductwork should be properly air sealed (Box 5-K) and also be protected from moisture absorption. Condensing
moisture can cause many types of insulation, such as fiberglass, to lose their insulating properties or degrade.
: Duct SealingBox 5-K
Duct sealing is critical to avoid air leaks that prevent the HVAC system from functioning as designed and
operated. The Code currently does not provide any guidance on ductwork sealing. The ASHRAE 90.1 energy
code can be referred to for appropriate seal levels for all ductwork in order to minimize energy losses from
the HVAC system. ASHRAE 90.1 (tables 6.2.4.3 A and 6.2.4.3 B) specify sealing requirements based on the
duct location, static pressure classification, and type of the duct (exhaust or return) as given below:
ASHRAE 90.1 Table 6.2.4.3 A
Minimum Duct Seal Level
Duct Location Duct Type Supply Exhaust Return
≤498.2 Pa ≥ 498.2 Pa
Outdoors A A C A
Unconditioned Spaces B A C B
Conditioned Spaces C B B C
ASHRAE 90.1 Table 6.2.4.3 B
Duct Seal Levels
Seal Level Sealing Requirements
A All transverse joints and longitudinal seams, and duct wall penetrations. Pressure-sensitive tape shall not be used
as the primary sealant.
B All transverse joints and longitudinal seams. Pressure-sensitive tape shall not be used as the primary sealant
C Transverse joints only.
System Balancing5.2.5
General5.2.5.1
System balancing is a process for maintaining the performance of an HVAC system, and for providing the occupants
with a comfortable conditioned space. Balancing an air or water-based HVAC system of buildings will make it more
energy-efficient, provide improved thermal comfort, extend the life of the building equipment and reduce the cost of
operating it. Balancing is achieved by optimizing the air/water distribution rates for the HVAC system.
As per the Code:
Construction documents shall require that all HVAC systems be balanced in accordance with generally accepted
engineering standards.
Construction documents shall require that a written balance report be provided to the owner or the designated
representative of the building owner for HVAC systems serving zones with a total conditioned area exceeding
500 m2 (5,000 ft2).
Box 5-L provides more information on the construction documents.
Box 5-L: Construction Documents
Construction documents provide vital information to the building owners on how to properly operate and
maintain a system that has been properly balanced. Verify during final inspection that an operations manual
has been passed on to the building owner and that it contains the following information at a minimum.
HVAC equipment capacity•
Equipment operation and maintenance manuals•
HVAC system control maintenance and calibration information, including wiring diagrams,•
schedules, and control sequence descriptions.
A complete written narrative of how each system is intended to operate.•

Air Systems Balancing5.2.5.1.1
Air System Balancing refers to the adjustment of airflow rates through air distribution system devices, such as
fans and diffusers. This is done by adjusting the position of dampers, splitter vanes, extractors, etc., manually or
by using automatic control devices, such as constant air volume or variable air volume boxes.
Balancing is necessary to verify that each space served by a system receives the air volume designed for that
space. Proper means for air balancing should be installed at each supply air outlet and zone terminal device.
These include balancing dampers or other means of supply-air adjustment provided in the branch ducts or at
each individual duct register, grille, or diffuser. Installation in the duct system of all devices used for balancing,
shown on the approved mechanical plans, typically, on the ductwork layout, should be verified.
As per the Code:
Air systems shall be balanced in a manner to minimize throttling losses. Then, for fans greater than 0.75 KW
(1.0 HP), fans must then be adjusted to meet design flow conditions.
Box 5-M provides the concepts related to air handling units for air distribution systems for energy efficiency.
: Air Handling Unit ConceptsBox 5-M
An air handler is responsible for moving air throughout the duct work in an air conditioning system. All air
handlers contain a blower motor and squirrel cage blower housing which facilitates the movement of air.
Most air handlers also include system controls, which are connected to the thermostat. Depending on the
type of system, an air handler can also be integrated with a gas, oil, electric furnace, heat pump, and cooling
coils (or evaporator coil for the air conditioning).
High-efficiency air distribution systems can substantially reduce fan power required by an HVAC system,
resulting in dramatic energy savings. The largest gains in efficiency for air distribution systems are realized in the
system design phase for new constructions or major retrofit projects. Passive or natural air transport systems
have the highest efficiency, and successful, modern examples of this approach are steadily accumulating. For
buildings that require mechanical ventilation, innovative design approaches and a methodical examination of
the entire air system can greatly improve efficiency and effectiveness.
Air-handling efficiency The energy required to move air is calculated as follows:
(Flow X Static Pressure) /Efficiency
All these factors can be manipulated to reduce the energy consumption of the system. Air flow has a dominant
effect on energy consumption because it shows up twice in the energy equation: as the first term and as a
squared function in the second term (pressure). The pressure a fan must work against depends on two primary
factors: the flow and duct design features such as diameter, length, surface treatment, and impediments such
as elbows, filters, and coils. Typical pressure losses are on the order of 2 to 6 inches water gauge (wg); an
efficient system operates at less than 1.5” wg. A fan’s duty factor is the number of hours per year that it
operates, sometimes presented as a percentage. Many large fans spin at full speed continuously (8,760 hours
per year). Using simple or complex controls, duty factors can often be reduced to about 3,000 hours per year
or less by limiting fan operation to occupied periods. The mechanical efficiency of the fan and its drive system
can typically be raised from the 40 to 60% range to the mid-80% range. Wire to air efficiency will need to be
considered and is function of motor efficiency x mechanical efficiency
Design options for improving air distribution efficiency include:
Variable-air-volume systems•
VAV diffusers•
Low-pressure-drop duct design•
Low-face-velocity air handlers•
Fan sizing and variable-frequency-drive motors•
Displacement ventilation systems.•
Hydronic Systems Balancing5.2.5.1.2
Hydronic System Balancing refers to the adjustment of water flow rates through distribution system devices,

such as pumps and coils, by manually adjusting the position of valves, or by using automatic control devices,
such as flow control valves.
When something is balanced, it is even on both sides. Therefore, a balanced hydronic system is one that delivers
even flow to all of the devices on that piping system. Each component has an effective equal length of pipe on
the supply and return. And when a system is balanced, all of the pressure drops are correct for the devices. When
that happens, the highest efficiencies are possible in the system. One need not have to change system supply
temperatures to accommodate one zone only. The system has the least amount of pressure drop possible, which
translates into reduced pumping costs. A balanced hydronic system is one that is efficient. If a system that is not
delivering the water to the right devices in the right amounts, then the system is out of balance.
As per the Code:
Hydronic systems shall be proportionately balanced in a manner to first minimize throttling losses; then the pump
impeller shall be trimmed or pump speed shall be adjusted to meet design flow conditions.
Exceptions to above:
Impellers need not be trimmed nor pump speed adjusted for pumps with pump motors of 7.5 kWa.
(10 hp) or less,
Impellers need not be trimmed when throttling results in no greater than 5% of the nameplateb.
horsepower draw, or 2.2 kW (3 hp), whichever is greater.
Condensers5.2.6
Condenser Locations5.2.6.1
A condenser is a heat exchanger that liquefies refrigerant vapor through heat removal. The typical condensing unit
houses a compressor, a condenser fan motor, and coils, along with controls which make all the components work
sequentially.
As per the Code:
Care shall be exercised in locating the condensers in such a manner that the heat sink is free of interference from heat
discharge by devices located in adjoining spaces and also does not interfere with such other systems installed nearby.
Condensers should be located in such a manner that there is no restriction to the air flow around the condenser
coils, there is no short-circuiting of discharge air to the intake side, and the heat discharge of other adjacent
equipment is not anywhere the air intake of the condenser.
Treated Water for Condensers5.2.6.2
Condenser water treatment is important to eliminate mineral buildup in condensers and chilled water systems.
Mineral deposits create poor heat transfer situations there by reducing the efficiency of the unit.
As per the Code:
All high-rise buildings using centralized cooling water system shall use soft water for the condenser and chilled
water system.
As per the Code:
The prescriptive requirements apply only if the HVAC system in the building meets the following criteria:
Serves a single zonea.
Cooling (if any) is provided by a unitary packaged or split-system air conditioner or heat pumpb.
Heating (if any) is provided by a unitary packaged or split-system heat pump, fuel-fired furnace,c.
electric resistance heater, or baseboards connected to a boiler
Outside air quantity is less than 1,400 l/s (3,000 cfm) and less than 70% of supply air at designd.
conditions

Other HVAC systems shall comply with ASHRAE 90.1-2004, §6.5.
: Single Zone for HVACBox 5-N
As per the Code, HVAC Zone is a space or group of spaces within a building with heating and cooling
requirements that are sufficiently similar so that desired conditions (e.g., temperature) can be maintained
throughout using a single sensor (e.g., thermostat or temperature sensor).
: Heat PumpBox 5-O
A heat pump consists of one or more factory-made assemblies that normally include indoor conditioning
coil, compressor, and outdoor coil, including means to provide a heating function. Heat pumps provide the
function of air heating with controlled temperature, and may include the functions of air cooling.
Economizers5.3.1
Economizers allow the use of outdoor air to cool the building when the outside temperature is cooler than that
inside. An economizer consists of dampers, sensors, actuators, and logic devices that together decide how much
outside air to bring into a building (See Figure 5.2).Under the right conditions, sensors and controls shut down
the compressor and bring in the outside air through the economizer louvers. A properly operating economizer
can cut energy costs by as much as 10% of a building’s total energy consumption, depending mostly on local
climate and internal cooling loads.
: EconomizerFigure 5.2
Source: E Source Cooling Atlas
Air-Side Economizers5.3.1.1
As per the Code:
Each individual cooling fan system that has a design supply capacity over 1,200 l/s (2,500 cfm) and a total
mechanical cooling capacity over 22 kW (6.3 tons) shall include either:
An air economizer capable of modulating outside-air and return-air dampers to supply 100% of thea.
design supply air quantity as outside-air; or

A water economizer capable of providing 100% of the expected system cooling load at outside airb.
temperatures of 10°C (50°F) dry-bulb/7.2°C (45°F) wet-bulb and below
Exceptions to above are:
Projects in the hot-dry and warm-humid climate zones are exempta.
Individual ceiling mounted fan systems < 3,200 l/s (6,500 cfm) are exemptb.
: EconomizersBox 5-P
Air Economizer
An air economizer is duct and damper arrangement and automatic control system that together allow a
cooling system to supply outdoor air to reduce or eliminate the need for mechanical cooling during mild or
cold weather.
Water Economizer
A water economizer is a system by which the supply air of a cooling system is cooled indirectly with water that
is itself cooled by heat or mass transfer to the environment without the use of mechanical cooling.
Partial Cooling5.3.1.2
One can use the building’s intrinsic thermal mass to reduce peak cooling loads by circulating cool night-time air
to pre-cool the building prior to daily occupancy in the cooling season. The building control system can operate
ventilation fans in the economizer mode on a scheduled basis. Care should be taken to prevent excessive fan
operation that would offset cooling energy savings. It is also ensured that night humidity does not preclude the
use of this strategy.
As per the Code:
Economizers shall be capable of providing partial cooling even when additional mechanical cooling is required
to meet the cooling load.
Testing of Air-Side Economizer5.3.1.3
As per the Code:
Air-side economizers shall be tested in the field following the requirements in Appendix F (of the Code) to
ensure proper operation.
Exception to above:
Air economizers installed by the HVAC system equipment manufacturer and certified to the building department
as being factory calibrated and tested per the procedures in Appendix F (of the Code).
Variable Flow Hydronic Systems5.3.2
Fluid from the heating or cooling source is supplied to heat transfer devices, such as coils and heat exchangers,
and back through the hydronic system. The Code specifies the type of equipment and capabilities in such a way
as to reduce pump energy. Variable fluid flow, automatic isolation valves, and variable speed drives enable the
system to operate below design flow when needed.
Variable Fluid Flow in Chilled or Hot Water System5.3.2.1
As per the Code:
Chilled or hot-water systems shall be designed for variable fluid flow and shall be capable of reducing pump
flow rates to no more than the larger of:
50% of the design flow rate, ora.
The minimum flow required by the equipment manufacturer for proper operation of the chillers orb.
boilers.

Automatic Isolation Valves5.3.2.2
Two-way automatic isolation valves serve as a means of varying flow rate in a hydronic system.
As per the Code:
Water cooled air-conditioning or heat pump units with a circulation pump motor greater than or equal to 3.7 kW (5
hp) shall have two-way automatic isolation valves on each water cooled air-conditioning or heat pump unit that are
interlocked with the compressor to shut off condenser water flow when the compressor is not operating.
Variable Speed Drives5.3.2.3
Variable speed drives are required to control chilled water and condenser water systems for energy efficiency.
As per the Code:
Chilled water or condenser water systems that must comply with either §5.3.2.1 or §5.3.2.2 (of ECBC) and that
have pump motors greater than or equal to 3.7 kW (5 hp) shall be controlled by variable speed drives.

Service Water Heating and Pumping
Service Water Heating and Pumping6.
General6.1
For some building types such as large hotels and hospitals service water heating can be major energy con-
sumer. Inefficiency in water heating is caused primarily by inefficiency of the heating equipment, and by
heat loss from hot water storage tanks and distribution piping network.
ECBC through mandatory requirements seeks to minimize energy usage in water heating systems by:
Utilizing solar water heating•
Specifying heating equipment efficiency•
Maximizing heat recovery and minimizing electric heating•
Insulating hot water storage tanks and pipelines•
Reducing standby losses•
Reducing heat and evaporation losses in heated swimming pools•
Solar Water Heating6.2.1
As per the Code:
Residential facilities, hotels and hospitals with a centralized system shall have solar water heating for at least 1/5
of the design capacity.
Exception to above:
Systems that use heat recovery for at least 1/5 of the design capacity.
There are two types of solar water heaters. Passive heaters collect and store solar thermal energy for water
heating applications and do not require electrical energy input for recirculating water through solar collector.
Active heaters collect and store solar thermal energy for water heating applications and require electrical energy
input for operation of recirculation pumps or other components. Figure 6.1 and Figure 6.2 show examples of
solar water heating systems.
An exception is provided by the Code for systems that use heat recovery systems for at least one-fifth (20%)
of the design capacity. For example heat is rejected from the air conditioner’s condenser to the atmosphere. By
recovering this waste heat and utilizing it to heat water, wherever feasible, it is possible to substantially reduce
water-heating costs.
Box 6-A provides information on various water heating systems normally used in practice.
: Types of Water HeatersBox 6-A
Storage Gas: A gas water heater designed to heat and store water at less than 80°C. Water temperature is
controlled with a thermostat.
Storage Electric: An electric water heater designed to heat and store water at less than 80°C. Water tem-
perature is controlled with a thermostat. Storage electric water heaters have a manufacturer’s specified capac-
ity of at least two gallons.
Storage Heat Pump: An electric water heater that uses a compressor to transfer thermal energy from one
temperature level to a higher temperature level for the purpose of heating water. It includes all necessary
auxiliary equipment such as fans, storage tanks, pumps or controls.
Instantaneous Gas: A gas water heater controlled manually or automatically by water flow activated control
or a combination of water flow and thermostatic controls.

Instantaneous Electric: An electric water heater controlled automatically by a thermostat, instantaneous
water heaters are not generally designed for use with solar water heating systems or as heat sources for
indirect fired water heaters. They are also typically inappropriate for use with recirculation systems. Refer
Box 6-B for more information.
Indirect Gas: A water heater consisting of a storage tank with no heating elements or combustion devices,
connected via piping and recirculating pump to a heat source consisting of a gas or oil fired boiler, or instan-
taneous gas water heater (see note following the definitions of Instantaneous Gas and Electric).
Passive Solar: Systems, which collect and store solar thermal energy for water heating applications and do
not require electricity to recirculate water through a solar collector.
Active Solar: Systems, which collect and store solar thermal energy for water heating applications requiring
electricity to operate pumps or other components.
The simplest systems are passive solar
water heaters, also called batch or bread
box collectors, they are most common in
regions that do not experience extensive
periods of below freezing temperatures.
The water in these solar collectors circulates
without the aid of pumps or controls.
: Batch Collector Passive SystemFigure 6.1
Active solar water heaters use
pumps to circulate water or an
antifreeze solution through heat-
absorbing solar thermal collectors.
: Active Indirect SystemFigure 6.2
Source: www.southface.org

: Instantaneous Water HeatersBox 6-B
Instantaneous water heaters provide hot water only as it is needed. They do not produce the standby
energy losses associated with storage water heaters, which can save money.
Water heaters heat water directly without the use of a storage tank. Therefore, they avoid the standby heat
losses associated with storage water heaters. When a hot water tap is turned on, cold water travels through
a pipe into the unit. Either a gas burner or an electric element heats the water. As a result, demand water
heaters deliver a constant supply of hot water. The heater dose not need a storage tank to fill up with
enough hot water. However, the water heater’s output limits the flow rate.
: Instantaneous Water HeaterFigure 6.3
Equipment Efficiency6.2.2
As per the Code:
Service water heating equipment shall meet or exceed the performance and minimum efficiency requirements
presented in available Indian Standards
Solar water heater shall meet the performance/minimum efficiency level mentioned in IS 13129 Parta.
(1&2)
Gas Instantaneous Water heaters shall meet the performance/minimum efficiency level mentioned inb.
IS 15558 with above 80% thermal efficiency
Electric water heater shall meet the performance /minimum efficiency level mentioned in IS 2082c.
The mandatory requirements for the Code include minimum efficiencies presented in relevant Indian Standards
for the various water heating equipment such as electric and gas heaters, instantaneous heaters, boilers, and pool
heaters.
For Solar water heating systems, IS 13129 (Part 1) provides information on the ‘Performance Rating Procedure
Using Indoor Test Methods’, and IS 13129 (Part 2) provides the information on the ‘Procedure for System
Performance Characterization and Yearly Performance Prediction’. These standards however, do not provide
any performance/minimum efficiency levels.
For Gas Instantaneous Water Heaters, IS 15558 describes the information and procedure for the measurement
of thermal efficiency of the heaters.
As per this Standard, thermal efficiency of the water heaters (under test conditions) shall not be less than:
84 percent for water heaters with a nominal heat input exceeding 10 kW•
82 percent for water heaters with a nominal heat input not exceeding 10 kW•
However, the Code specifies thermal efficiency of 80% or more.

For Electric Water Heaters, IS 2082 (Part 1) covers the safety and performance requirements of heaters with
rated capacities in the range of 6 liters to 200 liters. In these heaters, certain amount of energy is consumed
to keep the water hot while it is not being used. This consumption of electricity is called as standing loss (or
standby loss). Refer Box 6-C.
: Standby LossesBox 6-C
These losses account for energy lost while storing heated water. This includes any heat losses through the
water heater tank wall, fittings, and flue, plus any pilot light energy. Standby loss depends on the design and
insulation of the water heater, as well as the difference between the temperature of the water and that of the
air around the tank. Water heating energy can be reduced by decreasing standby losses.
The following table of IS 2082 (Part 1) specifies the standing loss in the heaters. For hot water temperature
difference of 45°C, in no case the standing loss should exceed the values specified in the Table 6.1.
: Standing Loss in Storage Type Electric Water HeatersTable 6.1
Rated Capacity in Liters Loss in kWh/day for 45º Difference
6 0.792
10 0.990
15 1.138
25 1.386
35 1.584
50 1.832
70 2.079
100 2.376
140 2.673
200 2.970
Source: IS 2082 (Part 1): 1993 (Reaffirmed 2004) Edition 5.4 (2002-05) Stationary Storage Type Electric Water
Heaters-Specification (Fourth Revision)
Supplementary Water Heating System6.2.3
As per the Code:
Supplemental Water Heating System shall be designed to maximize efficiency and shall incorporate and prioritize
the following design features as shown:
Maximum heat recovery from hot discharge system like condensers of air conditioning unitsa.
Use of gas-fired heaters wherever gas is availableb.
Electric heater as last resortc.
Piping Insulation6.2.4
As per the Code:
Piping insulation shall comply with §5.2.4.1. The entire hot water system including the storage tanks, pipelines
shall be insulated conforming to the relevant IS standards on materials and applications.
Table from 5.2.4.1 of this Guide for piping insulation is reproduced below.
: Insulation of Hot Water Piping.Table 6.2
Heating System
Designed Operating Temperature of Piping Insulation with Minimum R-value (m2·°K/W)
60°C and above 0.74
Above 40°C and below 60°C 0.35

Box 6-D and Box 6-E provide guidelines for hot water temperature controls and measures for improving
heating efficiency respectively.
: Guidelines for Temperature ControlsBox 6-D
Water-heating systems are required to have controls that are adjustable down to a 49°C setpoint or lower. An
exception is made where a higher setting is recommended by the manufacturer to prevent condensation and
possible corrosion. To comply with this requirement, the water heater must have thermostatic control with
an accessible setpoint. This setpoint must be adjustable down to whichever is lower: 49°C or the minimum
manufacturer’s recommended setting to prevent condensation. Both standby and distribution losses will be
minimized by designing a system to provide hot water at the minimum temperature required. In addition
to the potential energy savings, maintaining water temperature as low as possible reduces corrosion and
scaling of water heaters and components. Another important benefit is improved safety with respect to
scalding. Accidental scalding from temperatures as low as 60°C is responsible for numerous deaths each
year. Designers should be aware that the bacteria that cause Legionnaire’s Disease has been found in service
water heating systems and can colonize in hot water systems maintained below 46°C. Careful maintenance
practices can reduce the risk of contamination. In health-care facilities or service-water systems maintained
below 60°C, periodic flushing of the fixtures with high temperature water or other biological controls may
be appropriate.
: Guidelines for Improving Water Heating System EfficiencyBox 6-E
Reduce standby losses from storage tank and pipes.
Lower Water Heating Temperature: Use a hot water system with a thermostat. Service water heating en-
ergy use and operating costs can be reduced by simply lowering the thermostat setting on your water heater.
For each 5.5ºC (10ºF) reduction in water temperature, can save between 3%–5% in energy costs.
Insulate the storage tank: Install a water heater insulation blanket; the higher the R-value, the better. Use
wire or twine or straps to insure that the blanket stays in place. Some new high-efficiency heaters should not
be insulated; consult the equipment manual provided by the manufacturer. Gas water heaters should not be
insulated on top or within about 8” of the bottom of the water tank. Set an electric water heater on a rigid
foam insulation board. This step is most critical when the heater sits on a concrete slab, but it’s always a good
idea. Install the water heater in a heated location. The colder the air surrounding the heater, the more the
standby loss. Indoor gas heaters should be sealed combustion or fan-forced draft.
Insulate pipes and use heat traps: Insulate all exposed pipes. The R-value of pipe insulation is dependent
on wall thickness; thicker is better. A 5/8” wall thickness should be considered minimum for foam insula-
tion, while 3” is the minimum for fiberglass wrap. Heat trap nipples work best to eliminate convective losses
from the tank into the plumbing, but pipe loops also work if the drop is at least 6”.
Heat Traps6.2.5
Heat traps are valves or loops of pipe that allow water to flow into the water heater tank but prevent unwanted
hot-water flow out of the tank. The valves have balls inside that either float or sink into a seat, which stop
natural water circulation loop. Heat traps can help save energy and cost on the water heating bill by preventing
convective heat losses through the inlet and outlet pipes. These specially designed valves come in pairs. The
valves are designed differently for use in either the hot or cold water line.
As per the Code:
Vertical pipe risers serving storage water heaters and storage tanks not having integral heat traps and serving
a non-recirculating system shall have heat traps on both the inlet and outlet piping as close as practical to the
storage tank.
Heat traps may either be installed internally by the manufacturer, installed as an after-market add-on, or site-
fabricated. Site fabricated heat traps may be constructed by creating a loop or inverted U-shaped arrangement
to the inlet and outlet pipes (See Figure 6.4 for general guidance).

: Heat Trap ElementsFigure 6.4
Swimming Pools6.2.6
Heated swimming pools can be a source of considerable heat and water loss due to evaporation. Also, the
cost of the energy required to maintain the temperature of the water in the pool at a level comfortable for
swimming is a strong incentive to adopt measures which promote retention of heat in the pool and reduction
in heat loss.
As per the Code:
Heated pools shall be provided with a vapor retardant pool cover on or at the water surface. Pools heated to
more than 32°C (90°F) shall have a pool cover with a minimum insulation value of R-2.1 (R-12).
Exception to above:
Pools deriving over 60% of their energy from site-recovered energy or solar energy source.
Compliance Documentation6.2.7
As per the Code:
The application for approval shall furnish detailed calculation showing the design to ensure that at least 20% of
the heating requirement shall be met from solar heat/heat recovery and not more than 80% of the heat shall
be met from electrical heating. Wherever gas is available, not more than 20% of the heat shall be met from
electrical heating.

Lighting
Lighting7.
General7.1
Lighting accounts for 15% of total energy consumption in India. Lighting is an area that offers many
energy efficiency opportunities in almost any building facility, existing or new.
A century ago, a person could read by the light of a single candle, but today a person in a typical office uses
hundreds or even thousand times more light. Over the years, illumination standards have increased radically
along with efficiency of lamps.
People want light for different reasons, and a good lighting designer need to keep all of them in mind. Different
tasks and building facilities require different amounts and types of light. For example, a surgeon in an operation
theater needs lots of light with low glare and excellent color rendering, restaurant owners and diners often want
low light levels, corporate boardrooms call for lighting that reinforces a feeling of importance and success while
adapting to audio-visual presentations; retail outlets in many situations want to make their merchandise sparkle
so that it draws the customers and encourages them to buy. An office executive needs modest ambient lighting
level, good task lighting on work surface, and minimal glare to effectively read and work on computers.
While energy efficiency is an attractive goal for many reasons, lighting designers also need to consider a host of
other factors, including the effect of quality of light on the visual comfort and productivity of the occupants.
Small improvement in lighting quality can improve productivity of the user substantially. In practice, the right
quality and quantity of light can be provided efficiently (with less energy) by using the right technology and its
effective integration with daylight.
General Design Considerations
Using efficient lighting equipment and controls is the best way to ensure lighting energy efficiency while
maintaining or even improving lighting conditions. For instance, modern fluorescent lighting, such as
electronically ballasted T-8 systems, can provide the same quantity of light as older fluorescent lighting while
consuming as little as two-thirds of the energy. Similarly, compact fluorescent sources are three to four times
more efficient than the traditional incandescent lamps they are designed to replace.
For a lighting designer an energy-efficient lighting design involves sensitive integration of many requirements
and considerations that include building orientation, interior building layout, task illumination, daylight strategies,
glazing specification, choice of lighting system and controls etc. The designer is also responsible for making
sure that lighting complies with the Code, meeting both mandatory and prescriptive requirements.
The lighting requirements in the Code apply to:
Interior spaces of buildingsa.
Exterior building features, including façades, illuminated roofs, architectural features, entrances, exits,b.
loading docks, and illuminated canopies
Exterior building grounds lighting that is provided through the building’s electrical servicec.
Exceptions to above:
Emergency lighting that is automatically off during normal building operation and is powered bya.
battery, generator, or other alternate power source
Lighting in dwelling unitsb.
The mandatory requirements for lighting mostly relate to interior and exterior lighting controls.

Lighting
Lighting Control7.2.1
Lighting controls allow lighting to be turned down or completely off when it is not needed – the simplest way
to save energy. Maximizing the use of controls involves developing a set of strategies that utilize the Code
requirements for various devices, including on-off controls, dimming controls, and systems that combine the
use of both types of equipment. These controls can be quite sophisticated, but in general, they perform two
basic functions:1) they turn lights off when not needed, and 2) they modulate light output so that no more
light than necessary is produced. The equipment required to achieve these functions varies in complexity from
simple timers to intricate electronic dimming circuits, each applicable to different situations. Controls include
time clocks, occupant and motion sensors, automatic or manual daylighting controls, and astronomical time
switches (the automatic switches that adjust for the length of the day as it varies over the year).
: Manual Vs. Automatic ControlsBox 7-A
Manual lighting controls range from a single switch to a bank of switches and dimmers that are actuated by
toggles, rotary knobs, push buttons, remote control, and other means. Manual controls can be cost-effective
options for small-scale situations. However, as the lighting system becomes larger, automated systems become
more cost-effective and are better at controlling light. Manual controls may not give the desired results in real
situations because the decision to shut off the lights when they are not needed is based entirely on human
initiative. It is worthwhile to determine the amount of local vs. central control that is needed from the lighting
control system.
Automatic Lighting Shutoff7.2.1.1
Although there is no simpler way to reduce the amount of energy consumed by lighting systems than to
manually turn lights off whenever not needed, this is not done as often as it could be. In response to that
problem, the Code requires several automatic switches that either work on time schedule or sense the presence
of occupants.
Automatic Control Strategies
Several different approaches can be used to control electric lighting. The control hardware and design practices
are discussed below:
Scheduling Control:• Use a time scheduling device to control lighting systems according to
predetermined schedules.
Occupancy Sensing:• Control lights in response to the presence or absence of people in the space.
Daylighting:• Switch or dim electric lights in response to the presence or absence of daylight illumination
in the space.
Lumen Maintenance:• Gradually adjust electric light levels over time to correspond with the
depreciation of light output from aging lamps.
As per the Code:
Interior lighting systems in buildings larger than 500 m2 (5,000 ft²) shall be equipped with an automatic control
device. Within these buildings, all office areas less than 30 m2 (300 ft2) enclosed by walls or ceiling-height
partitions, all meeting and conference rooms, all school classrooms, and all storage spaces shall be equipped
with occupancy sensors. For other spaces, this automatic control device shall function on either
A scheduled basis at specific programmed times. An independent program schedule shall be provideda.
for areas of no more than 2,500 m2 (25,000 ft²) and not more than one floor; or,
Occupancy sensors that shall turn the lighting off within 30 minutes of an occupant leaving theb.
space. Light fixtures controlled by occupancy sensors shall have a wall-mounted, manual switch
capable of turning off lights when the space is occupied.
Exception to above:
Lighting systems designed for 24-hour use.

Lighting
Box 7-B provides a brief on scheduling controls.
Box 7-B: Scheduling Controls
Programmable timing, also known as automatic time scheduling, is the oldest form of automatic lighting
control. Time scheduling manages the on and off times of a building’s lighting systems.
Scheduling systems function by turning off all or some of the lights when a building space is unoccupied. In the
most basic time-scheduling scheme, a time switch switches lighting circuits on or off based on programmable
schedules. For example, exterior lighting is usually switched on to correspond to sundown and is switched
off again at daybreak. By contrast, time scheduling of interior lighting systems is based, for the most part, on
occupancy schedules. In some cases, time switches are used to energize additional lighting control systems,
such as daylighting controls, which are held off during unoccupied periods. Time-scheduling systems employ
the following components:
A central processor is usually capable of controlling several output channels, each of which may•
be assigned to one or more lighting circuits.
Relays are series-wired to lighting control zones and are controlled by the central processor.•
Overrides are required to accommodate individuals who use the space during scheduled off•
hours. Individuals can activate manual switches or use telephone overrides to regain temporary
control of the lights in a given space.
Occupant-sensing devices are an alternative to scheduling controls and an acceptable means of meeting the
requirement for automatic shutoff. The designer is free to arrange occupant sensing controls in any manner
that makes sense for the building design. In office spaces, each room or space might have an occupant sensor.
Of course, the smaller the area controlled, the greater the energy savings will be. In open office areas, several
occupant sensors may be connected so that the lights remain on if any one of the sensors detects occupants.
However, in order to satisfy the requirement, it is necessary that all the general lighting be controlled by one or
more occupant sensors.
Box 7-C provides more information on occupancy sensors.
Box 7-C: Occupancy Sensors
Occupancy sensors are automatic scheduling devices that detect motion and turn lights on and off accordingly.
Most devices can be calibrated for sensitivity and for the length-of-time delay between the last detected
occupancy and extinguishing of the lights. The most energy-efficient occupancy sensors, known as “manual-
on, automatic-off,” require that the user manually switch on the lights when entering a controlled zone (the
“lights off” function is still automatic).
Occupancy sensor systems typically consist of a motion detector, a control unit, and a relay. Usually, two or
more of the components are integrated into one package. Most systems also require a power supply in the
form of a transformer, which steps down the building voltage to 24V. The detector collects information, then
sends it to the controller, where it is processed. Output from the controller activates the relay, which in turn
switches the light circuit.
There are two major types of occupancy controls.
Wallbox• units are designed to fit into a standard wall switch box and operate on the building volt-
age (i.e., a separate power supply is not required). They are excellent, inexpensive replacements
for standard wall switches. Their main limitation is their relatively short range. Consequently, they
tend to be used in small offices and meeting rooms.
Wall and Ceiling• units typically contain an integrated sensor/controller unit wired (Class 2) to a
switch pack containing the relay and power supply. They are far more popular than wallbox units
and have very few application limitations.

Lighting
Occupancy-sensing lighting controls represent a refinement of the technology developed in the early 1970s
to detect intruders for residential and commercial security applications. With lighting control, two different
means of detecting occupancy are used:
Passive Infrared (PIR) sensors• perceive and respond to the heat patterns of motion. This same
technology is used in most residential and commercial security systems. The chief advantage of
PIR sensors is that they are relatively inexpensive and reliable. They very rarely “false trigger”
(that is, respond to non occupant motion in a space). The major limitation of PIR sensors is that
they are strictly line-of-sight devices, unable to see around corners or partitions.
Ultrasound (US) detectors• radiate ultrasonic waves into a space, then read the frequency of the re-
flected waves. Motion causes a slight shift in frequency, which the detector interprets as occupancy.
They are more sensitive than PIR sensors, which is both an advantage and a disadvantage. They are
often used very effectively in partitioned spaces but are also more prone to false triggering due to
their sensitivity to air movement. Proper design and installation minimizes this potential problem.
Space Control7.2.1.2
Along with controls for individual lights or sets of fixtures, master controls are required for each space which
can shut off all the lights within the space. For example, the last person leaving the office is much more likely to
use a master switch than to go through the office turning off every switch. Similarly, a cleaning crew can easily
use master switches to turn lights off at the end of a working day.
As per Code:
Each space enclosed by ceiling-height partitions is required to have at least one control device to independently
control the lighting within the space. The device can be a switch that is activated either manually or automatically
by sensing an occupant sensor. Each control device, regardless of type, shall have the following functions:
Control a maximum of 250 ma. 2 (2,500 ft2) for a space less than or equal to 1,000 m2 (10,000 ft2), and a
maximum of 1,000 m2 (10,000 ft2) for a space greater than 1,000 m2 (10,000 ft2)
Be capable of overriding the required shutoff control [ECBC 7.2.1.1] for no more than 2 hoursb.
Be readily accessible and located so the occupant can see the control.c.
Box 7-D summarizes the Code requirements.
: Space Area and Lighting ControlsBox 7-D
S.No. Space Area Coverage Area for each control device
1 Up to 1000 m2 250 m2 max.
2 More than 1000 m2 1000 m2 max.
Exception to (c) above:
The required control device may be remotely installed if required for reasons of safety or security. A remotely
located device shall have a pilot light indicator as part of or next to the control device and shall be clearly labeled
to identify the controlled lighting.
An exception to (c) is provided for control devices that need to be remotely installed for reasons of safety or
security. However, a remotely located device must have a pilot light indicator as part of or next to the control
device and it must be clearly labeled to identify the controlled lighting device.

Lighting
: Lighting ControlsBox 7-E
Q: An open office area is 900 m2. How many controls are required for this space?
A: Minimum four, since this space is smaller than 1,000 m2 and each space control can serve a maximum
area of 250 m2.
Q: In an open office 1,500 m2, how many minimum controls are required?
A: Minimum two, since this space is larger than 1,000 m2 each control can serve a maximum area of 1,000 m2.
Control in Daylighted Areas7.2.1.3
As per the Code:
Luminaire in daylighted areas greater than 25 m2 (250 ft2) shall be equipped with either a manual or automatic
control device that:
Is capable of reducing the light output of the luminaires in the daylighted areas by at least 50%•
Controls only the luminaires located entirely within the daylighted area.•
: LuminaireBox 7-F
As per ECBC:
A complete lighting unit consisting of a lamp or lamps together with the housing designed to distribute the
light, position and protect the lamps, and connect the lamps to the power supply.
Appendix A of ECBC provides more information on the daylighted area.
Exterior Lighting Control7.2.1.4
As per the Code:
Lighting for all exterior applications not exempted in §7.3.5 (of the Code) shall be controlled by a photosensor
or astronomical time switch that is capable of automatically turning off the exterior lighting when daylight is
available or the lighting is not required.
Additional Control7.2.1.5
As per the Code:
The following specialty lighting spaces are required to have a control device that separates lighting control from
that of the general lighting
The following lighting applications shall be equipped with a control device to control such lighting independently
of general lighting:
Display/Accent Lighting:a. Display or accent lighting greater than 300 m2 (3,000 ft2) area shall have a
separate control device
Case Lighting:b. Lighting in cases used for display purposes greater than 300 m2 (3,000 ft2) area shall be
equipped with a separate control device
Hotel and Motel Guest Room Lighting:c. Hotel and motel guest rooms and guest suites shall have
a master control device at the main room entry that controls all permanently installed luminaires and
switched receptacles
Task Lighting:d. Supplemental task lighting including permanently installed under-shelf or under-
cabinet lighting shall have a control device integral to the luminaires or be controlled by a wall-mounted
control device provided the control device complies with §7.2.1.2 (of ECBC)
Non-visual Lighting:e. Lighting for non-visual applications, such as plant growth and food-warming,
shall be equipped with a separate control device

Lighting
Demonstration Lighting:f. Lighting equipment that is for sale or for demonstrations in lighting
education shall be equipped with a separate control device accessible only to authorized personnel
Box 7-G provides more information and guidelines for installation of controls for the above lighting
applications:
Box 7-G: Additional Control
Many special lighting applications must be controlled separately, including display lighting in retail stores, case
lighting, hotel/motel guest rooms, task lighting, non-visual lighting applications, and demonstration lighting.
These are discussed below.
Display/Accent Lighting
Lighting used to highlight artwork or merchandise in retail stores, art galleries, lobbies, and other spaces
must have a separate lighting control. This additional control can save considerable energy since the hours
required for display lighting are generally fewer than the hours that the space is occupied. In a retail store, for
instance, employees typically arrive one to two hours before the store opens in order to prepare the store, and
often employees need to stay for an hour or two after the store closes. Without a separate control for display
lighting, the display lighting would have to be operated for two to four hours each day when it isn’t needed.
Controls for display lighting can be situated in remote locations, but it is advisable that they have indicator
lights and be clearly marked to indicate which lighting is controlled.
Case Lighting
Lighting is frequently installed in closed casework for the display of jewelry and other fine merchandise. Such
lighting is required to have a separate control from that used for general illumination of the space. The reason
for this requirement is the same as for display lighting: the case lighting is only needed during store hours, not
during the entire occupancy period of the space. Usually, the control for case lighting is integral to the case.
Hotel/Motel Guest Room Lighting
A master lighting control is required at the entry door of hotel and motel guest rooms to control all permanently
installed luminaires and switched receptacles. The control is usually a three-way device wired in combination
with local controls. In multiple-room suites, a single master control must be located at the main entrance. This
master lighting control allows guests or the housekeeping staff to turn off all permanently installed luminaires
when they are exiting the room.
Task Lighting
All supplemental task lighting in a space shall have a separate control. Desk lamps will inherently meet this
requirement,buttherequirementalsoappliestopermanentlyinstalledunder-shelf orunder-cabinetlighting.Such
lighting can have a switch integral to the luminaires or be controlled by a wall-mounted control device, provided
the control device is accessible and the controlled lighting can be observed when the switch is toggled.
Non-Visual Lighting
Lighting needed for non-visual purposes, such as plant growth or food warming, must have a separate control.
This is because such lighting is likely to be needed at different times than the general lighting.
Demonstration Lighting
Lighting on display in retail lighting stores and lighting that is being demonstrated in classrooms and lighting
education facilities must have a separate control. Again, the justification is that such lighting is operated on a
separate schedule from the general lighting.
Exit Signs7.2.2
As per the Code:
Internally-illuminated exit signs shall not exceed 5W per face.
Electrically powered exit signs normally use incandescent bulbs. Most LED and some CFL exit signs can meet
ECBC requirement. Due to their low power consumption, LED exit signs can be purchased with built-in back-
up power supplies (i.e., batteries). With an estimated service life of 10 years or more, LEDs require significantly
fewer lamp replacements than exit signs equipped with either incandescent lamps or CFLs.

Lighting
Exterior Building Grounds Lighting7.2.3
As per the Code:
Lighting for exterior building grounds luminaires which operate at greater than 100W shall contain lamps having a
minimum efficacy of 60 lm/W unless the luminaire is controlled by a motion sensor or exempt under §7.1 of ECBC.
Efficacy of Lamp (with or without ballast) is the lumens produced by a lamp/ballast system divided by the total
watts of input power (including the ballast), expressed in lumens per watt.
Figure 7.1 and Figure 7.2 provide a broad range of lamp efficacy of commonly used lamps. As shown below
in Figure 7.2, luminaires meeting exterior building ground lighting requirements can be fluorescent, mercury
vapor and high pressure sodium.
: Relative Efficacy of Major Light Sources (Lumens/Watt)Figure 7.1
: Watts per Lighting System EfficiencyFigure 7.2

Lighting
: Lighting ControlsBox 7-H
High-efficiency lighting components, such as T-8 fluorescent lamps and electronic high-frequency ballasts,
make a significant impact on lighting energy and its associated costs by reducing the kW required to illuminate
buildings. Lighting controls, on the other hand, affect lighting energy by directly reducing lighting’s time of
use. Some lighting control techniques, such as using photocell controls in building spaces that incorporate
daylighting, not only reduce lighting time of use but also decrease lighting power and may even reduce the
average cost of electricity by eliminating some lighting kW during peak demand periods.
Source: ASHRAE Manual 2004.
The prescriptive requirements of the Code regulates both interior and exterior lighting power.
Interior Lighting Power7.3.1
The prescriptive lighting requirements limit the installed electric wattage for interior building lighting. As with the
other sections of the Code, however, these lighting power requirements are minimum requirements. Designers
working on specific projects may often be able to design more efficient lighting systems.
For interior lighting power requirements, the installed lighting power used by luminaires, including lamps,
ballasts, current regulators, and central devices (except as specifically exempted in 7.1) is first calculated using the
procedure discussed under 7.3.4.1 of ECBC. Calculated installed power is then compared with the maximum
permissible Interior Light Power Densities, specified for various building types (Building Area Method) or
building space functions (Space Function Method) under table 7.1 and 7.2 of ECBC respectively. These two are
discussed in more detail at 7.3.2 and 7.3.3.
: Lighting Power AllowanceBox 7-I
Interior lighting power allowance: the maximum lighting power in watts allowed for the interior of a1.
building
Exterior lighting power allowance: the maximum lighting power in watts allowed for the exterior of a2.
building
Interior lighting includes all permanently installed general and task lighting shown on the plans. Interior lighting,
for a building or a separately metered or permitted portion of a building, shall not exceed allowed power
limits.
The building area method is the simplest method to follow since fewer calculations are required. However, if
the project applies to only a portion of the entire building, is not listed as a building type, or has more than one
occupancy type, the space function method should be used to determine compliance.
Trade-off of lighting power allowances are not permitted between portions of a building where different
methods are used.
There are many exceptions to the lighting power requirement, generally for specialized lighting. These are listed in
ECBC §7.3.1.
Building Area Method7.3.2
This method provides the procedure of calculating total watts per square meter for the entire building based on
its type. The sum of all the interior lighting power for various areas of the building cannot exceed the total watts
to be in compliance. The first step is to identify the allowed power lighting density for appropriate building area
types listed in Table 7.1 of ECBC. If more than one listed type applies to the area, the more general building
area type should be used.

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The second step is to calculate the gross lighted floor area for each of the building area types (this can be
done using the building plans). Finally, the last step is to multiply the allowed watts per square meter listed
for each selected building type by the corresponding lighted floor areas to determine the allowed light power
allowance.
Table 7.1: Interior Lighting Power- Building Area Method (ECBC Table 7.1)
Building Area Type LPD (W/m2) Building Area Type LPD (W/m2)
Automotive Facility 9.7 Multifamily Residential 7.5
Convention Center 12.9 Museum 11.8
Dining: Bar Lounge/Leisure 14.0 Office 10.8
Dining: Cafeteria/Fast Food 15.1 Parking Garage 3.2
Dining: Family 17.2 Performing Arts Theater 17.2
Dormitory/Hostel 10.8 Police/Fire Station 10.8
Gymnasium 11.8 Post Office/Town Hall 11.8
Health care-Clinic 10.8 Religious Building 14.0
Hospital/Health Care 12.9 Retail/Mall 16.1
Hotel 10.8 School/University 12.9
Library 14.0 Sports Arena 11.8
Manufacturing Facility 14.0 Transportation 10.8
Motel 10.8 Warehouse 8.6
Motion Picture Theater 12.9 Workshop 15.1
In cases where both a general building area type and a specific building area type are listed, the specific building
area type shall apply.
Space Function Method7.3.3
Similar to the building area method, the first step of the space function method is to identify the appropriate
building type and their allowed lighting power densities, which varies according to the function of the space.
These are listed in ECBC Table 7.2, Interior Lighting Power – Space Function Method.
: Interior Lighting Power- Space Function Method (ECBC Table 7.2)Table 7.2
Space Function LPD (W/m2) Space Function LPD (W/m2)
Office-enclosed 11.8 For Reading Area• 12.9
Office-open plan 11.8 Hospital
Conference/Meeting/Multipurpose 14.0 For Emergency• 29.1
Classroom/Lecture/Training 15.1 For Recovery• 8.6
Lobby* 14.0 For Nurse Station• 10.8
For Hotel• 11.8 For Exam Treatment• 16.1
For Performing Arts Theater• 35.5 For Pharmacy• 12.9
For Motion Picture Theater• 11.8 For Patient Room• 7.5
Audience/Seating Area* 9.7 For Operating Room• 23.7
For Gymnasium• 4.3 For Nursery• 6.5
For Convention Center• 7.5 For Medical Supply• 15.1
For Religious Buildings• 18.3 For Physical Therapy• 9.7
For Sports Arena• 4.3 For Radiology• 4.3
For Performing Arts Theater• 28.0 For Laundry – Washing• 6.5
For Motion Picture Theater• 12.9 Automotive – Service Repair 7.5
For Transportation• 5.4 Manufacturing Facility
Atrium-first three floors 6.5 For Low Bay (<8m ceiling)• 12.9
Atrium-each additional floor 2.2 For High Bay (>8m ceiling)• 18.3

Lighting
Lounge/Recreation* 12.9 For Detailed Manufacturing• 22.6
For Hospital• 8.6 For Equipment Room• 12.9
Dining Area* 9.7 For Control Room• 5.4
For Hotel• 14.0 Hotel/Motel Guest Rooms 11.8
For Motel• 12.9 Dormitory – Living Quarters 11.8
For Bar Lounge/Leisure Dining• 15.1 Museum
For Family Dining• 22.6 For General Exhibition• 10.8
Food Preparation• 12.9 For Restoration• 18.3
Laboratory 15.1 Bank Office – Banking Activity Area 16.1
Restrooms 9.7 Retail
Dressing/Locker/Fitting Room 6.5 For Sales Area• 18.3
Corridor/Transition* 5.4 For Mall Concourse• 18.3
For Hospital• 10.8 Sports Arena
For Manufacturing Facility• 5.4 For Ring Sports Area• 29.1
Stairs-active 6.5 For Court Sports Area• 24.8
Active Storage* 8.6 For Indoor Field Area• 15.1
For Hospital• 9.7 Warehouse
Inactive Storage* 3.2 For Fine Material Storage• 15.1
For Museum• 8.6 For Medium/Bulky Material•
Storage
9.7
Electrical/Mechanical Facility 16.1 Parking Garage – Garage Area 2.2
Workshop 20.5 Transportation
Convention Center – Exhibit Space 14.0 For Airport – Concourse• 6.5
Library For Air/Train/Bus – Baggage•
Area
10.8
For Card File & Cataloging• 11.8 For Ticket Counter Terminal• 16.1
For Stacks• 18.3
* For all facilities except the following
Second, for each space that is enclosed by partitions which are 80% or greater than ceiling height, the gross
interior floor area must be determined. This applies to all space area types except for retail. The gross interior
floor area should be calculated by measuring to the center of the partition walls and must also include spaces
allotted to balconies or other projections.
Finally, the individual lighting power allowances for each space is determined by multiplying its gross lighted
floor area by the allowed lighting power density for that space. The lighting power allowances are summed to
equal the Interior Lighting Power Allowance for the building.
Installed Interior Lighting Power7.3.4
As per the Code:
The installed interior lighting power calculated for compliance with §7.3 of the Code shall include all power
used by the luminaires, including lamps, ballasts, current regulators, and control devices except as specifically
exempted in §7.1 of the Code.
Exception to above:
If two or more independently operating lighting systems in a space are controlled to prevent simultaneous
user operation, the installed interior lighting power shall be based solely on the lighting system with the highest
power.

Lighting
Luminaire Wattage7.3.4.1
The Code requires that luminaire wattage be incorporated into the installed interior lighting power calculation
as follows:
The wattage of incandescent luminaires with medium base sockets and not containing permanentlya.
installed ballasts shall be the maximum labeled wattage of the luminaires
The wattage of luminaires containing permanently installed ballasts shall be the operating input wattageb.
of the specified lamp/ballast combination based on values from manufacturers’ catalogs or values from
independent testing laboratory reports
The wattage of all other miscellaneous luminaire types not described in (a) or (b) shall be the specifiedc.
wattage of the luminaires
The wattage of lighting track, plug-in busway, and flexible-lighting systems that allow the addition and/d.
or relocation of luminaires without altering the wiring of the system shall be the larger of the specified
wattage of the luminaires included in the system or 135 W/m (45 W/ft). Systems with integral overload
protection, such as fuses or circuit breakers, shall be rated at 100% of the maximum rated load of the
limiting device
Exterior Lighting Power7.3.5
Lighting power limits are specified for building exterior lighting applications in Table 7.3 of the Code. The
connected lighting power for these applications must not exceed these allowed limits. In addition, trade-offs
between applications are not permitted.
Exemptions are allowed for the following lighting applications, only if they are equipped by an independent
control device:
Specialized signal, directional, and marker lighting associated with transportationa.
Lighting used to highlight features of public monuments and registered historic landmark structuresb.
or buildings
Lighting that is integral to advertising signagec.
Lighting that is specifically designated as required by a health or life safety statute, ordinance, ord.
regulation
Any exterior lighting applications not listed in Table 7.3 of the Code, and not exempt (as described above), are
required to simply comply with the mandatory requirements in §7.2.3 of the Code. This requires luminaires
operating at greater than 100W to contain lamps with minimum efficacy of 60 lm/W, unless the luminaire is
controlled by a motion sensor.
Table 7.3: Exterior Lighting Building Power (ECBC Table 7.3)
Exterior Lighting Applications Power Limits
Building entrance (with canopy) 13 W/m2 (1.3 W/ft2) of canopied area
Building entrance (without canopy) 90 W/lin m (30 W/lin f) of door width
Building exit 60 W/lin m (20 W/lin f) of door width
Building facades 2 W/m2 (0.2 W/ft2) of vertical facade area

Electrical Power
Electrical Power8.
General8.1
ECBC has only mandatory requirements for electric power systems installed in buildings. These provisions
are related to distribution transformers, electric motors, power factor, and distribution losses.
The mandatory requirements of the Code, cover the following electrical equipment and systems of building:
Transformers•
Energy- Efficient Motors•
Power Factor Correction•
Electrical Metering and Monitoring•
Power Distribution Systems•
Transformers8.2.1
Transformer is a static device, which is used to either increase (Step up) or decrease (Step down) the input
supply voltage depending on the application and requirement. Transformers consist of two or more coils that
are electrically insulated, but magnetically linked (see Figure 8.1). The primary coil connected to the power
source and secondary coil connects to the load.
: TransformerFigure 8.1
Power transmitted from power plants, is in the form of high-tension voltage (400 kV - 33 kV). The reasons for
transmitting HT voltage are:
Reduced conductor size and investment on conductors•
Reduced the transmission losses and voltage drop.•
At the user end, equipment with various voltage rating is used for different applications. Hence, the transmitted
voltage is first stepped down (11 kV - 230V) through distribution transformers and then the power supply is
distributed to the various sections and equipment. Distribution transformers are used normally in all commercial
buildings. They are kept energized around the clock providing power to the building’s electrical equipment.
Maximum Allowable Power Transformer Losses8.2.1.1
Transformers are of two types - Dry type and Oil filled. Fire safety and environmental concerns associated
with transformers are important. Oil filled transformers are not installed at fire hazardous places. Dry type
transformer is used when it has to be located near the load center which may be in a hazardous place. As there
is no oil used in the transformer and special type of fire resistant insulation are used for the windings, the fire
risk is considerably reduced in these transformers.

Electrical Power
Distribution transformers consume energy even when the building is not occupied or its equipment are not
operating, resulting in energy loss. Transformers losses are discussed in Box 8-A.
: Transformer Efficiency and LossesBox 8-A
The efficiency of transformers normally varies anywhere between 96 to 99 percent. The efficiency not only
depends on the design, but also, on the effective operating load. Transformer losses consist of two parts:
No-load Loss and Load Loss
No-load Loss (also called core loss) is the power consumed to sustain the magnetic field in the transformer's
steel core. Core loss occurs whenever the transformer is energized; and it does not vary with load. Core losses
are caused by two factors: hysteresis and eddy current losses. Hysteresis loss is that energy loss caused by
reversing of the magnetic field in the core as the magnetizing alternating current rises and falls and reverses
direction. Eddy current loss is a result of induced currents circulating in the core.
Load Loss (also called copper loss) is associated with full-load current flow in the transformer windings.
Copper loss is power lost in the primary and secondary windings of a transformer due to the ohmic resistance
of the windings. Copper loss varies with the square of the load current. (P=I2R).
Transformer losses as a percentage of load is given in the Figure 8.2.
:Figure 8.2 Transformer loss vs % Load
For a given transformer, the manufacturer can supply values for no-load loss, PNo-load, and load loss, PLoad.
The total transformer loss, PTotal, at any load level can then be calculated from:
PTotal = PNo-load+ (% Load/100)2 × PLoad
Source: Energy Efficiency in Electrical Utilities, Bureau of Energy Efficiency, 2005.
As per the Code:
Power transformers of the proper ratings and design must be selected to satisfy the minimum acceptable
efficiency at 50% and full load rating. In addition, the transformer must be selected such that it minimizes
the total of its initial cost in addition to the present value of the cost of its total lost energy while serving its
estimated loads during its respective life span.
ECBC lists various transformer sizes of dry-type and oil-filled transformers and their associated losses at 50%
and full load rating (Table 8.1 and Table 8.2 of ECBC).

Electrical Power
Table 8.1: Dry-Type Transformers (ECBC Table 8.1)
Rating KVA Max. Losses at
50% loading1
[kW]
Max. Losses at
100% loading1
[kW]
Total losses at
50% loading1
[kW]
Total losses
at rated load1
[kW]
Up to 22 kV class 33 kV class
100 0.94 2.4 1.12 2.4
160 1.29 3.3 1.42 3.3
200 1.5 3.8 1.75 4
250 1.7 4.32 1.97 4.6
315 2 5.04 2.4 5.4
400 2.38 6.04 2.9 6.8
500 2.8 7.25 3.3 7.8
630 3.34 8.82 3.95 9.2
800 3.88 10.24 4.65 11.4
1000 4.5 12 5.3 12.8
1250 5.19 13.87 6.25 14.5
1600 6.32 16.8 7.5 18
2000 7.5 20 8.88 21.4
2500 9.25 24.75 10.75 26.5
1Total loss values given in above table are applicable for thermal classes E, B & F and have component of load loss at reference
temperature according to clause 17 of IS 2026: Part 11. i.e., average winding temperature rise as given in column 2 of Table 8.2 plus
30°C. An increase of 7% on total for thermal class H is allowed.
Table 8.2: Oil Filled Transformers (ECBC Table 8.2)
Rating KVA Max. Losses at
50% loading1
[kW]
Max. Losses at
100% loading1
[kW]
Total losses at
50% loading1
[kW]
Total losses
at rated load1
[kW]
Up to 11 kV class 33 kV class
100 0.52 1.80 0.56 1.82
160 0.77 2.20 0.78 2.58
200 0.89 2.70 0.90 3.00
250 1.05 3.32 -- --
315 1.10 3.63 1.30 4.30
400 1.45 4.63 1.52 5.10
500 1.60 5.50 1.95 6.45
630 2.00 6.64 2.30 7.60
1000 3.00 9.80 3.45 11.35
1250 3.60 12.00 4.00 13.25
1600 4.50 15.00 4.85 16.00
2000 5.40 18.40 5.70 18.50
2500 6.50 22.50 7.05 23.00
1Total loss values given in above table are applicable for thermal classes E, B & F and have component of load loss at reference
temperature according to clause 17 of IS 2026: Part 11. i.e., average winding temperature rise as given in column 2 of Table 8.2 plus
30°C. An increase of 7% on total for thermal class H is allowed.
Measurement and Reporting of Transformer Losses8.2.1.2
As per the Code:
All measurement of losses shall be carried out by using calibrated digital meters of class 0.5 or better accuracy
and certified by the manufacturer. All transformers of capacity of 500 kVA and above would be equipped with
additional metering class current transformers (CTs) and potential transformers (PTs) additional to requirements
of Utilities so that periodic loss monitoring study may be carried out.

Electrical Power
Energy-Efficient Motors8.2.2
Electric motors convert electrical energy into mechanical energy. Induction motors are the most commonly
used prime mover for various equipment in buildings. In induction motors, the induced magnetic field of the
stator winding induces a current in the rotor. This induced rotor current produces a second magnetic field,
which tries to oppose the stator magnetic field, and this causes the rotor to rotate.
The 3-phase squirrel cage induction motor is the workhorse of most applications; it is rugged and reliable,
and is by far the most common motor type used. These motors drive pumps, blowers and fans, compressors,
conveyers and production lines. The 3-phase induction motor has three windings each connected to a separate
phase of the power supply. Box 8-B provides more information on the induction motors.
: Induction motorsBox 8-B
The induction motor is the dominant motor in use today with over 90 percent of the installed horsepower—
largely because it is rugged, has no brushes or slip rings, and is simple, reliable, and cheap. Figure 7-2 shows
the spectrum of common motor types including induction motors.
As with most motors, the induction motor has stator and rotor magnetic fields that interact to spin a shaft which
provides torque for performing useful work. The stator and rotor magnetic fields in an induction motor are
each created differently. The stator field results from applying AC voltage directly to copper windings distributed
around the circumference of the stator, causing the magnetic field to rotate with the sinusoidally varying
input power. The speed at which the stator field rotates—the motor’s synchronous speed— depends on the
construction of the motor. The induction motor is unique in how it develops its rotor field. Typically, the rotor
has bars that circulate currents that generate the rotor field. Instead of connecting the bars to a power supply as
for the stator field, or otherwise creating a field using a permanent magnet, the rotor field is created by current
induced in the rotor bars by the rotating stator field. The rotor field thus rotates at the same speed as the stator
field; however, it is offset by a certain angle that increases as more motor torque is required.
Although induction motors are normally considered fixed speed machines, one potential disadvantage is
that their operating speed will change with both load and voltage. In fact, it is difficult to find two induction
motors that will operate at exactly the same speed, even when operated at identical voltage and frequency, and
driving identical loads.
There are two major classes of induction motors, varying in winding pattern and construction: squirrel-cage
motors—in which conductive bars mounted in the laminated rotor and held by heavy end rings that short-
circuit them at both ends, form the rotor windings— and wound-rotor motors, in which coils of wire form
the rotor windings. In wound-rotor motors, the windings are generally connected via slip rings and brushes
to a variable resistance which can vary the motor’s speed and torque.
Induction motors can be constructed so that different pole pairs can be connected and disconnected as
desired at the terminal box, producing a variety of speeds. Such squirrel-cage induction motors are multispeed
(usually two speed), but are not variable-speed if operating from a supply at fixed frequency. In another
variation, part-winding start induction motors energize part of the winding when starting and the rest later,
in one or more steps, so as to reduce starting torque or current.
Induction motors can be constructed for single or polyphase operation with most motors over 20 horsepower
designed for three-phase power.
Source: E- Source Technology Atlas Series Volume IV, Drive Power
Motor Efficiency is the ratio of the useful mechanical power output to the total electric power input to the motor.
Like all electromechanical equipment, motors consume some “extra” energy in order to make the conversion.
Efficiency reflects how much total energy a motor uses in relation to the rated power delivered to the shaft.
A motor’s nameplate rating is based on output horsepower, which is fixed for continuous operation at full load.
The amount of input power needed to produce rated horsepower will vary from motor to motor, with more-
efficient motors requiring less input wattage than less-efficient models to produce the same output. Electrical
energy input is measured in watts, while output is given in horsepower. Output power for motors may also be
stated in watts or kilowatts. One horsepower is equivalent to 746 watts.

Electrical Power
As per the Code:
Motors shall comply with the following:
All permanently wired polyphase motors of 0.375 kW or more serving the building and expected toa.
operate more than 1,500 hours per year and all permanently wired polyphase motors of 50kW or more
serving the building and expected to operate more than 500 hours per year shall have a minimum
acceptable nominal full load motor efficiency not less than IS 12615 for energy-efficient motors. (Refer
Table 8.3, Table 8.4, Table 8.5, and Table 8.6.)
Motors of horsepower differing from those listed in the table shall have efficiency greater than that ofb.
the next listed kW motor
Motor horsepower ratings shall not exceed 20% of the calculated maximum load being servedc. (Refer
Box 8-C)
Motor nameplates shall list the nominal full-load motor efficiencies and the full-load power factord.
Motor users should insist on proper rewinding practices for any rewound motors. If the propere.
rewinding practices cannot be assured, the damaged motor should be replaced with a new, efficient one
rather than suffer the significant efficiency penalty associated with typical rewind practices (Refer Box
8-D for more information)
Certificates shall be obtained and kept on record indicating the motor efficiency. Whenever a motorf.
is rewound, appropriate measures shall be taken so that the core characteristics of the motor is not
lost due to thermal and mechanical stress during removal of damaged parts. After rewinding, a new
efficiency test shall be performed and a similar record shall be maintained
Table 8.3: Values of Performance Characteristic of Two Pole Energy-Efficient Induction Motors.
Rated
Output
Frame
Designation
Full
Load
Speed
Min
Full
Load
Current
Max
Breakaway
Torque in
Terms of Full
Load Torque
Min
Breakaway
Current in Terms
of Full Current,
Equal or Below
Nominal
Efficiency
For eff 2 For eff 1 For eff 2 For eff 1
kW Rev/min Amp Percent Percent Percent Percent Percent
(1) (2) (3) (4) (5) (6) (7) (8) (9)
0.37 71 2790 1.2 170.0 600 650 66.0 70.2
0.55 71 2760 1.6 170.0 600 650 70.0 74.0
0.75 80 2780 2.0 170.0 600 650 73.0 77.0
1.1 80 2790 2.8 170.0 600 650 76.2 82.8
1.5 90S 2800 3.7 170.0 600 650 78.5 84.1
2.2 90L 2810 5.0 170.0 650 700 81.0 85.6
3.7 100L 2820 8.0 160.0 650 700 84.0 87.5
5.5 132S 2830 11.0 160.0 650 700 85.7 88.6
7.5 132S 2840 15.0 160.0 650 700 87.0 89.5
9.3 160M 2840 18.5 160.0 650 700 87.7 90.0
11.0 160M 2860 21.5 160.0 650 700 88.4 90.5
15.0 160M 2870 29.0 160.0 650 700 89.4 91.3
18.5 160L 2880 35.0 160.0 650 700 90.0 91.8
22.0 180M 2890 41.5 160.0 650 700 90.5 92.2
30.0 200L 2900 54.0 160.0 650 700 91.4 92.9
37.0 200L 2900 67.0 160.0 650 700 92.0 93.3
45.0 225M 2955 80.0 160.0 650 700 92.5 93.7
55.0 250M 2960 95.0 160.0 650 700 93.0 94.0
75.0 280S 2970 130.0 160.0 650 700 93.6 94.6
90.0 280M 2970 150.0 160.0 650 700 93.9 95.0

Electrical Power
110.0 315S 2980 185.0 160.0 650 700 94.0 95.0
125.0 315M 2980 209.0 160.0 650 700 94.5 95.3
132.01) 315M 2980 220.0 160.0 650 700 94.5 95.3
160.01) 315L 2980 265.0 160.0 650 700 94.8 95.5
Note: Output to frame size relation is maintained in accordance with 1S 1231 for all motors, except those
marked as 1), wherein the frame size indicated is “preferred frame size.”
Source: IS 12615: 2004, Energy-Efficient Induction Motors --- Three-Phase Squirrel Cage (First Revision)
Table 8.4: Values of Performance Characteristic of 4 Pole Energy-Efficient Induction Motors.
Rated
Output
Frame
Designation
Full
Load
Speed
Min
Full
Load
Current
Max
Breakaway
Torque in
Terms of Full
Load Torque
Min
Breakaway
Current in Terms
of Full Current,
Equal or Below
Nominal
Efficiency
(1) (2) (3) (4) (5) (6) (7) (8) (9)
0.37 71 1330 1.4 170.0 550 600 66.0 73.0
0.55 80 1340 1.7 170.0 550 600 70.0 78.0
0.75 80 1360 2.2 170.0 550 600 73.0 82.5
1.1 90S 1370 2.9 170.0 550 600 76.2 83.8
1.5 90L 1380 3.8 170.0 550 600 78.5 85.0
2.2 100L 1390 5.1 170.0 600 700 81.0 86.4
3.7 112M 1410 8.1 160.0 600 700 84.0 88.3
5.5 132S 1420 11.4 160.0 600 700 85.7 89.2
7.5 132M 1430 15.4 160.0 600 700 87.0 90.1
9.3 160M 1430 18.5 160.0 600 700 87.7 90.5
11.0 160M 1440 22.0 160.0 600 700 88.4 91.0
15.0 160L 1440 30.0 160.0 600 700 89.4 91.8
18.5 180M 1440 36.0 160.0 600 700 90.0 92.2
22.0 180L 1440 43.0 160.0 600 700 90.5 92.6
30.0 200L 1450 56.0 160.0 600 700 91.4 93.2
37.0 225S 1450 69.0 160.0 650 700 92.0 93.6
45.0 225M 1460 84.0 160.0 600 700 92.5 93.9
55.0 250M 1460 99.0 160.0 600 700 93.0 94.2
75.0 280S 1470 134.0 160.0 600 700 93.6 94.7
90.0 280M 1470 164.0 160.0 600 700 93.9 95.0
110.0 315S 1480 204.0 160.0 600 700 94.4 95.2
125.0 315M 1480 234.0 160.0 600 700 94.7 95.5
132.01) 315M 1480 247.0 160.0 600 700 94.7 95.5
160.01) 315L 1480 288.0. 160.0 600 700 95.0 95.8
Note: Output to frame size relation is maintained in accordance with IS 1231 for all motors, except those

Electrical Power
Rated
Output
Frame
Designation
Full
Load
Speed
Min
Full
Load
Current
Max
Breakaway
Torque in
Terms of Full
Load Torque
Min
Breakaway
Current in Terms
of Full Current,
Equal or Below
Nominal
Efficiency
For eff 2 For eff 1 For eff 2 For
eff 1
kW Rev/min Amp Percent Percent Percent Percent P e r -
cent
(1) (2) (3) (4) (5) (6) (7) (8) (9)
0.37 80 870 1.4 160.0 550 600 65.0 69.4
0.55 80 870 1.9 160.0 550 600 68.0 72.0
0.75 90S 890 2.3 160.0 550 600 71.0 74.6
1.1 90L 900 3.2 160.0 550 600 74.0 77.3
1.5 100L 900 4.0 160.0 550 600 76.0 79.6
2.2 112M 910 5.5 150.0 600 700 79.0 82.2
3.7 132S 920 8.8 150.0 600 700 82.5 85.1
5.5 132M 920 12.7 150.0 600 700 84.5 86.8
7.5 160M 930 16.7 150.0 600 700 86.0 88.1
9.3 160L 930 20.5 140.0 600 700 87.0 89.3
11.0 160L 935 23.0. 140.0 600 700 87.5 89.7
15.0 180L 940 30.5 140.0 600 700 88.5 90.5
18.5 200L 940 37.5 140.0 600 700 89.5 91.3
22.0 200L 945 44.0 140.0 600 700 90.0 91.8
30.0 225M 945 59.0 140.0 600 700 91.0 92.6
37.0 250M 950 72.0 140.0 600 700 91.5 93.0
45.0 280S 960 87.0 140.0 600 700 92.0 93.4
55.0 280M 960 107.0 140.0 600 700 92.5 93.8
75.0 315S 970 145.0 140.0 600 700 93.0 94.2
90.0 315M 970 175.0 140.0 600 700 93.3 94.5
110.01) 315M 970 214.0 140.0 600 700 93.5 94.6
132.01) 315L 980 257.0 140.0 600 700 93.8 94.9
Note: Output to frame size relation is maintained in accordance with IS 1231 for all motors, except those
Rated
Output
Frame
Designation
Full
Load
Speed
Min
Full
Load
Current
Max
Breakaway
Torque in
Terms of Full
Load Torque
Min
Breakaway
Current in Terms
of Full Current,
Equal or Below
Nominal
Efficiency
(1) (2) (3) (4) (5) (6) (7) (8) (9)
0.37 90S 640 1.5 150.0 550 600 62.0 66.8
0.55 90L 640 2.1 150.0 550 600 67.0 71.1
0.75 100L 650 2.7 150.0 550 600 70.0 73.8

Electrical Power
1.1 100L 660 3.5 150.0 550 600 72.0 76.2
1.5 112M 670 4.5 150.0 550 600 74.0 77.9
2.2 I32S 680 6.1 140.0 600 700 77.0 80.5
3.7 160M 690 9.8 140.0 600 700 80.0 83.0
5.5 160M 690 14.2 140.0 600 700 82.5 85.1
7.5 160L 695 19.0 140.0 600 700 84.0 86.4
9.3 180L 700 23.0 140.0 600 700 85.0 87.3
11.0 180L 700 26.0 140.0 600 700 86.0 88.1
15.0 200L 705 35.0 130.0 600 600 87.0 89.0
18.5 225S 705 45.0 130.0 600 700 88.0 89.8
22.0 225M 710 52.0 130.0 600 700 88.5 90.2
30.0 250M 710 70.0 130.0 600 700 90.0 91.5
37.0 280S 710 86.0 130.0 600 700 90.5 90.5
45.0 280M 720 99.0 130.0 600 700 91.0 92.4
55.0 315S 720 118.0 130.0 600 700 91.5 92.8
75.0 315M 730 153.0 130.0 600 700 92.3 93.5
90.01) 315L 730 182.0 130.0 600 700 92.8 93.9
110.01) 315L 730 218.0 130.0 600 700 93.3 94.3
Note: Output to frame size relation is maintained in accordance with 1S 1231 for all motors, except those
: Consequences of Motor Over SizingBox 8-C
When motors are oversized and operate for extended periods at
significantly less than full load, there are three significant operational
penalties – reduced efficiency, reduced slip (important if the load is a
cube-law type), and reduced power factor.
Depending on the motor, efficiency will typically peak at somewhere
between 75% load and full load. The larger the motor and the higher
its peak efficiency, the more likely it will have a relatively flat efficiency
curve between 50% load and full load, with a hump at 75% load
some 0.3 to 1% points higher than at full load. Efficiency drops
precipitously below 50% load, with the average 100-hp energy-
efficient motor losing over two points between 50 and 25% load and
the average 100-hp standard efficiency induction motor dropping
some 5.5 points over the same range. Smaller motors lose even more,
particularly at lower efficiencies
A general rule-of-thumb is that a one percentage point increase in
efficiency is equivalent to about a one-third-point increase in slip – a decrease in slip can therefore quickly
negate even a significant energy efficiency improvement (Figure 8.3)
: Increase in efficiencyFigure 8.3
(Percentage points)
: Motor Rewinding versus ReplacementBox 8-D
Motor failures are frequently caused by bearing failures and are often accompanied by the breakdown of
the coils of insulated wire inside the motor (the stator windings) and other problems. When a motor fails,
the owner is faced with deciding whether to rebuild it or replace it. Rebuilding, commonly called rewinding,
usually entails a lower initial cost compared to a replacement motor, especially for larger motors. Rewinding
can preserve and, in rare cases, slightly improve motor efficiency if skillfully done. However, the rewinding
process provides many avenues by which the motor efficiency can be degraded, greatly increasing operating
cost and energy consumption.

Electrical Power
To ensure the highest quality in repaired motors, the consistent use of test equipment and documentation
procedures must be integral parts of the repair process, so that the efficiency of the motor and the quality of
its components can be verified before the motor is put back into service.
A critical task in most motor rebuilds is to remove the old windings without altering the adjacent laminated
steel cores, and then to wrap new insulated wire around the old cores (Figure 8.4.)
Stator Core
Back Iron
Tooth
Slot
Air Gap
Rotor Core
Rotor Bar
: Profile cutaway of an induction motor stator and rotorFigure 8.4
The old windings are commonly embedded in thick coats of varnish (used to glue the windings inside the
core slots) which prevent their easy removal. Heat, chemicals, or mechanical force are commonly used to
loosen and pull out old windings; excessive use of any of these can cause damage to the cores. Improper
machining, replacement bearings, wire diameter, and winding technique can all compound, resulting in a
rebuilt motor with poor performance and lower efficiency.
Although it is technically possible to rebuild a motor to its original specifications, survey results of actual rewind
practices show that this is seldom the case. On the average, rewound motors are less efficient than they were
before rewinding. The magnitude of this problem can vary widely from one rewind shop to another, and can
only be properly identified when efficiency measurements are taken before and after rewinding.
Source: E- Source Technology Atlas Series Volume IV, Drive Power
Power Factor Correction8.2.3
As per the Code:
All electricity supplies exceeding 100 A, 3 phases shall maintain their power factor between 0.95 lag and unity
at the point of connection.
Power factor correction is the process of adjusting the characteristics of electric loads in order to improve power
factor so that it is closer to unity (i.e. 1). In simplified, electrical terminology, power factor is the difference
between real (kW) and reactive power (kVAR). It is a measure of how effectively current is being converted into
useful work output and, more specifically, is a good indicator of the effect of the load current on the efficiency
of the supply system. Power factor correction (PFC) may be applied either by an electrical power transmission
utility to improve the stability and efficiency of the transmission network or, correction may be installed by
individual electrical customers to, for example, reduce costs charged to them by their electricity supplier while
simultaneously improving energy efficiency. A high power factor is generally desirable in a transmission system
to reduce transmission losses and improve voltage regulation at the load. PFC is normally achieved by the
addition of capacitors to the electrical network which reduce the burden on the supply. Box 8-E gives more
information on the subject.
: Power Factor CorrectionBox 8-E
What are some of the benefits of Power Factor Correction?
Reduced power consumption•
Reduced electricity bills•
Improved electrical energy efficiency•
Extra kVA availability from the existing supply•
Reduced I• 2R losses from transformer and distribution equipment

Electrical Power
Minimized voltage drop in long cables.•
What are some ways to correct the power factor?
Minimize operation of idling or lightly loaded motors•
Avoid operation of equipment above its rated voltage•
Replace standard motors as they burn out with energy-efficient motors. Even with energy-efficient•
motors, however, the power factor is significantly affected by variations in load. A motor must be
operated near its rated capacity to realize the benefits of a high power factor design.
Install capacitors in your AC circuit to decrease the magnitude of reactive power.•
Check-Metering and Monitoring8.2.4
A significant barrier to achieving energy efficiency during the operation of a building is inadequate metering
systems and monitoring plans. Building operators cannot be expected to manage energy if they cannot measure
energy use. To improve a building’s energy performance over its operating life, and optimize the energy-efficient
requirements, the Code requires that the building’s performance be measured.
Metering is about having information that allows buildings energy managers to analyze and track changes
in energy demand and, therefore, to manage their energy consumption more effectively. Energy metering is
not a new concept and has been used by large energy-intensive buildings for many years to monitor energy
consumption.
The Code requires check-metering based on following three scenarios:
Services exceeding 1000 kVA shall have permanently installed electrical metering to record demanda.
(kVA), energy (kWh), and total power factor. The metering shall also display current (in each phase
and the neutral), voltage (between phases and between each phase and neutral), and Total Harmonic
Distortion (THD) as a percentage of total current
Services not exceeding 1000 kVA but over 65 kVA shall have permanently installed electric metering tob.
record demand (kW), energy (kWh), and total power factor (or kVARh)
Services not exceeding 65 kVA shall have permanently installed electrical metering to record energyc.
(kWh)
Power Distribution Systems8.2.5
Power Distribution System Losses8.2.5.1
As per the Code:
The power cabling shall be adequately sized as to maintain the distribution losses not to exceed 1% of the total
power usage. Record of design calculation for the losses shall be maintained.
An engineer or contractor can demonstrate the real savings as well as the advantages of lower generated heat
and increased flexibility of the installation with a properly sized distribution system. In addition, when less heat
is generated, the result is reduced energy requirements for fans and air conditioning systems.

Appendix A: ECBC Definitions, Abbreviations and Acronyms
Energy Conservation Building Code (ECBC) User Guide A.1
APPENDIX A: ECBC Definitions,
Abbreviations and Acronyms
General9.1
Certain terms, abbreviations, and acronyms are defined in this section for the purposes of this code. These
definitions are applicable to all sections of this code. Terms that are not defined shall have their ordinarily
accepted meanings within the context in which they are used. Webster’s Third New International Dictionary
of the English Language, Unabridged, copyright 1986, shall be considered as providing ordinarily accepted
meanings.
Definitions9.2
Addition: an extension or increase in floor area or height of a building outside of the existing building
envelope
Alteration: any change, rearrangement, replacement, or addition to a building or its systems and equipment;
any modification in construction or building equipment
Annual fuel utilization efficiency (AFUE): an efficiency description of the ratio of annual output energy
to annual input energy as developed in accordance with requirements of U.S. Department of Energy (DOE)
10CFR Part 430
Astronomical time switch: an automatic time switch that makes an adjustment for the length of the day as it varies
over the year
Authority having jurisdiction: the agency or agent responsible for enforcing this Code
Automatic: self-acting, operating by its own mechanism when actuated by some non-manual influence, such as
a change in current strength, pressure, temperature, or mechanical configuration.
Automatic control device: a device capable of automatically turning loads off and on without manual
intervention
Balancing, air system: adjusting airflow rates through air distribution system devices, such as fans and
diffusers, by manually adjusting the position of dampers, splitters vanes, extractors, etc., or by using automatic
control devices, such as constant air volume or variable air volume boxes
Balancing, hydronic system: adjusting water flow rates through hydronic distribution system devices, such
as pumps and coils, by manually adjusting the position valves, or by using automatic control devices, such as
automatic flow control valves
Ballast: a device used in conjunction with an electric-discharge lamp to cause the lamp to start and operate
under proper circuit conations of voltage, current, waveform, electrode heat, etc.
Boiler: a self-contained low-pressure appliance for supplying steam or hot water
Boiler, packaged: a boiler that is shipped complete with heating equipment, mechanical draft equipment, and
automatic controls; usually shipped in one or more sections. A packaged boiler includes factory-built boilers
manufactured as a unit or system, disassembled for shipment, and reassembled at the site.
Building: a structure wholly or partially enclosed within exterior walls, or within exterior and party walls, and
a roof, affording shelter to persons, animals, or property.

Building, existing: a building or portion thereof that was previously occupied or approved for occupancy by
the Authority Having Jurisdiction
Building complex: a group of buildings in a contiguous area under single ownership
Building entrance: any doorway, set of doors, turnstiles, or other form of portal that is ordinarily used to gain
access to the building by its users and occupants
Building envelope: the exterior plus the semi-exterior portions of a building. For the purposes of determining
building envelope requirements, the classifications are defined as follows:
Building envelope, exterior: the elements of a building that separate conditioned spaces from the exterior
Building envelope, semi-exterior: the elements of a building that separate conditioned space from
unconditioned space or that enclose semi-heated spaces through which thermal energy may be transferred to or
from the exterior, or to or from unconditioned spaces, or to or from conditioned spaces
Building exit: any doorway, set of doors, or other form of portal that is ordinarily used only for emergency
egress or convenience exit
Building grounds lighting: lighting provided through a building’s electrical service for parking lot, site,
roadway, pedestrian pathway, loading dock, and security applications
Building material: any element of the building envelope through which heat flows and that heat is included
in the component U-factor calculations other than air films and insulation
Circuit breaker: a device designed to open and close a circuit by nonautomatic means and to open the circuit
automatically at a predetermined over-current without damage to itself when properly applied within its rating
Class of construction: for the building envelope, a subcategory of roof, wall, floor, slab-on-grade floor, opaque
door, vertical fenestration, or skylight
Coefficient Of Performance (COP) – cooling: the ratio of the rate of heat removal to the rate of energy
input, in consistent units, for a complete refrigerating system or some specific portion of that system under
designated operating conditions
Coefficient Of Performance (COP) – heating: the ratio of the rate of heat delivered to the rate of energy
input, in consistent units, for a complete heat pump system, including the compressor and, if applicable, auxiliary
heat, under designated operating conditions
Commercial building: all buildings except for multi-family buildings of three stories or fewer above grade
and single-family buildings
Construction documents: drawings and specifications used to construct a building, building systems, or
portions thereof
Control: to regulate the operation of equipment
Control device: a specialized device used to regulate the operation of equipment
Constant Volume System: a space-conditioning system that delivers a fixed amount of air to each space. The
volume of air is set during the system commissioning.
Cool roof: a property of a surface that describes its ability to reflect and reject heat. Cool roof surfaces have
both a light color (high solar reflectance) and a high emittance (can reject heat back to the environment)
Daylighted area: the daylight illuminated floor area under horizontal fenestration (skylight) or adjacent to
vertical fenestration (window), described as follows:
Effective Aperture: Visible Light Transmittance x Window-to-Wall Ratio (EA = VLT x WWR).

Horizontal Fenestration: the area under a skylight, monitor, or sawtooth configuration with an effective
aperture greater than 0.001 (0.1%). The daylighted area is calculated as the horizontal dimension in each direction
equal to the top aperture dimension in that direction plus either the floor-to-ceiling height (H) for skylights, or
1.5 H for monitors, or H or 2H for the sawtooth configuration, or the distance to the nearest 1000 mm (42 in)
or higher opaque partition, or one-half the distance to an adjacent skylight or vertical glazing, whichever is least,
as shown in the plan and section figures below.
Vertical Fenestration: the floor area adjacent to side apertures (vertical fenestration in walls) with an effective
aperture greater than 0.06 (6%). The daylighted area extends into the space perpendicular to the side aperture a
distance either two times the head height of the side aperture or to the nearest 1.35 m (54 in) or higher opaque
partition, whichever is less. In the direction parallel to the window, the daylighted area extends a horizontal
dimension equal to the width of the window plus either 1 m (3.3 ft) on each side of the aperture, the distance
to an opaque partition, or one-half the distance to an adjacent skylight or window, whichever is least.

Dead band: the range of values within which a sensed variable can vary without initiating a change in the
controlled process
Demand: the highest amount of power (average KW over an interval) recorded for a building or facility in a
selected time frame
Design capacity: output capacity of a system or piece of equipment at design conditions
Design conditions: specified environmental conditions, such as temperature and light intensity, required to be
produced and maintained by a system and under which the system must operate
Distribution system: a device or group of devices or other means by which the conductors of a circuit can be
disconnected from their source of supply
Door: all operable opening areas (which are not fenestration) in the building envelope, including swinging and roll-
up doors, fire doors, and access hatches. Doors that are more than one-half glass are considered fenestration. For
the purposes of determining building envelope requirements, the classifications are defined as follows:
Door, non-swinging: roll-up sliding, and all other doors that are not swinging doors.
Door, swinging: all operable opaque panels with hinges on one side and opaque revolving doors.
Door area: total area of the door measured using the rough opening and including the door slab and the
frame.
Dwelling unit: a single unit providing complete independent living facilities for one or more persons, including
permanent provisions for living, sleeping, eating, cooking, and sanitation
Economizer, air: a duct and damper arrangement and automatic control system that together allow a cooling
system to supply outdoor air to reduce or eliminate the need for mechanical cooling during mild or cold
weather
Economizer, water: a system by which the supply air of a cooling system is cooled indirectly with water that
is itself cooled by heat or mass transfer to the environment without the use of mechanical cooling
Effective aperture: Visible Light Transmittance X Window-to-wall Ratio. (EA = VLT X WWR)
Effective aperture, horizontal fenestration: a measure of the amount of daylight that enters a space through
horizontal fenestration (skylights). It is the ratio of the skylight area times the visible light transmission divided
by the gross roof area above the daylighted area. (See also daylighted area.)
Effective aperture, vertical fenestration: a measure of the amount of daylight that enters a space through
vertical fenestration. It is the ratio of the daylight window area times its visible light transmission plus half the
vision glass area times its visible light transmission and the sum is divided by the gross wall area. Daylighted
window area is located 2.2 m (7 ft) or more above the floor and vision window area is located above 1 m (3 ft)
but below 2.2 m (7 ft). The window area, for the purposes of determining effective aperture shall not include
windows located in light wells when the angle of obstruction (α) of objects obscuring the sky dome is greater
than 70o, measured from the horizontal, nor shall it include window area located below a height of 1 m (3 ft).
(See also daylighted area.)
Efficacy: the lumens produced by a lamp/ballast system divided by the total watts of input power (including
the ballast), expressed in lumens per watt
Efficiency: performance at a specified rating condition
Remittance: the ratio of the radiant heat flux emitted by a specimen to that emitted by a blackbody at the same
temperature and under the same conditions
Enclosed building: a building that is totally enclosed by walls, floors, roofs, and openable devices such as
doors and operable windows

Energy: the capacity for doing work. It takes a number of forms that may be transformed from one into
another such as thermal (heat), mechanical (work), electrical, and chemical. Customary measurements are watts
(W)
Energy Efficiency Ratio (EER): performance of smaller chillers and rooftop units is frequently measured in
EER rather than 1/η (kW/ton). It is the ratio of net cooling capacity in Btu/h to total rate of electric input in
watts under designated operating conditions. The higher the EER, the more efficient the unit
Energy Factor (EF): a measure of water heater overall efficiency
Envelope performance factor: the trade-off value for the building envelope performance compliance option
calculated using the procedures specified in Section 12-Appendix D. For the purposes of determining building
envelope requirements the classifications are defined as follows:
Base envelope performance factor: the building envelope performance factor for the base design
Proposed envelope performance factor: the building envelope performance factor for the Proposed Design
Equipment: devices for comfort conditioned, electric power, lighting, transportation, or service water heating
including, but not limited to, furnaces, boilers, air conditioners, heat pumps, chillers, water heaters, lamps,
luminaries, ballasts, elevators, escalators, or other devices or installations
Equipment, existing: equipment previously installed in an existing building
Façade area: area of the façade, including overhanging soffits, cornices, and protruding columns, measured in
elevation in a vertical plane, parallel to the plane of the face of the building. Non-horizontal roof surfaces shall
be included in the calculations of vertical façade area by measuring the area in a plane parallel to the surface.
Fan system power: the sum of the nominal power demand (nameplate W or HP) of motors of all fans that
are required to operate at design conditions to supply air from the heating or cooling source to the conditioned
space(s) and return it to the source of exhaust it to the outdoors.
Fenestration: all areas (including the frames) in the building envelope that let in light, including windows,
plastic panels, clerestories, skylights, glass doors that are more than one-half glass, and glass block walls.
Skylight: a fenestration surface having a slope of less than 60 degrees from the horizontal plane. Other
fenestration, even if mounted on the roof of a building, is considered vertical fenestration.
Fenestration area: total area of the fenestration measured using the rough opening and including the glazing,
sash, and frame. For doors where the glazed vision area is less than 50% of the door area, the fenestration area
is the glazed vision area. For all other doors, the fenestration area is the door area.
Floor area gross: the sum of the floor areas of the spaces within the building including basements, mezzanine
and intermediate-floored tiers, and penthouses with headroom height of 2.5 m (7.5 ft) or greater. It is measured
from the exterior faces of exterior walls or from the centerline of walls separating buildings, but excluding
covered walkways, open roofed-over areas, porches and similar spaces, pipe trenches, exterior terraces or steps,
chimneys, roof overhangs, and similar features.
Gross building envelope floor area: the gross floor area of the building envelope, but excluding slab-on-
grade floors.
Gross conditioned floor area: the gross floor area of conditioned spaces.
Gross lighted floor area: the gross floor area of lighted spaces.
Gross semi heated floor area: the gross floor area of semi heated spaces.
Flue damper: a device in the flue outlet or in the inlet of or upstream of the draft control device of an individual,
automatically operated, fossil fuel-fired appliance that is designed to automatically open the flue outlet during
appliance operation and to automatically close the flue outlet when then appliance is in standby condition.

Fossil fuel: fuel derived from a hydrocarbon deposit such as petroleum, coal, or natural gas derived from living
matter of a previous geologic time.
Fuel: a material that may be used to produce heat or generate power by combustion.
Generally accepted engineer standard: a specification, rule, guide, or procedure in the field of engineering,
or related thereto, recognized and accepted as authoritative.
Grade: the finished ground level adjoining a building at all exterior walls.
Guest room: any room or rooms used or intended to be used by a guest for sleeping purposes.
Heat capacity: the amount of heat necessary to raise the temperature of a given mass 1°C (1°F). Numerically,
the heat capacity per unit area of surface (W/m2
·K [Btu/ft2
-°F]) is the sum of the products of the mass per unit
area of each individual material in the roof, wall, or floor surface multiplied by its individual specific heat.
Heat Pump: A heat pump consists of one or more factory-made assemblies that normally include indoor
conditioning coil, compressor, and outdoor coil, including means to provide a heating function. Heat pumps
provide the function of air heating with controlled temperature, and may include the functions of air cooling,
air circulation, air cleaning, dehumidifying, or humidifying.
Heating Seasonal Performance Factor (HSPF): the total heating output of a heat pump during its normal
annual usage period for heating (in Btu) divided by the total electric energy input during the same period.
Historic: a building or space that has been specifically designed as historically significant.
HVACsystem:theequipment,distributionsystems,andterminalsthatprovide,eithercollectivelyorindividually,
the processes of heating, ventilating, or air conditioned to a building or portion of a building.
Infiltration: the uncontrolled inward air leakage through cracks and crevices in any building element and
around windows and doors of a building caused by pressure differences across these elements due to factors
such as wind, inside and outside temperature differences (stack effect), and imbalance between supply and
exhaust air systems.
Installed interior lighting power: the power in watts of all permanently installed general, task, and furniture
lighting systems and luminaires.
Integrated part-load value: a single number figure of merit based on part-load EER, COP, or 1/η (kW/
ton) expressing part-load efficiency for air-conditioning and heat pump equipment on the basis of weighted
operation at various load capacities for the equipment.
Kilovolt-ampere: where the term “kilovolt-ampere” (kVA) is used in this Code, it is the product of the
line current (amperes) times the nominal system voltage (kilovolts) times 1.732 for three-phase currents. For
single-phase applications, kVA is the product of the line current (amperes) times the nominal system voltage
(kilovolts).
Kilowatt: the basic unit of electric power, equal to 1000 W.
Labeled: equipment or materials to which a symbol or other identifying mark has been attached by the
manufacturer indicating compliance with specified standard or performance in a specified manner.
Lamp: a generic term for man-made light source often called bulb or tube.
Lighted floor area, gross: the gross floor area of lighted spaces.
Lighting, decorative: lighting that is purely ornamental and installed for aesthetic effect. Decorative lighting
shall not include general lighting.
Lighting, emergency: lighting that provides illumination only when there is a general lighting failure.
Lighting, general: lighting that provides a substantially uniform level of illumination throughout an area.

General lighting shall not include decorative lighting or lighting that provides a dissimilar level of illumination
to serve a specialized application or feature within such area.
Lighting Efficacy (LE): the quotient of the total lumens emitted from a lamp or lamp/ballast combination
divided by the watts of input power, expressed in lumens per watt.
Lighting system: a group of luminaires circuited or controlled to perform a specific function.
Lighting power allowance:
Interior lighting power allowance: the maximum lighting power in watts allowed for the interior of a
building
Exterior lighting power allowance: the maximum lighting power in watts allowed for the exterior of a
building
Lighting Power Density (LPD): the maximum lighting power per unit of area of a building classification of
space function.
Low-rise residential: single-family houses, multi-family structures of three stories or fewer above grade,
manufactured houses (mobile homes), and manufactured houses (modular).
Lumen: It is the unit of total light output from a light source. If a lamp or fixture were surrounded by a
transparent bubble, the total light flow through the bubble is measured in lumens. Lamps are rated in lumens,
which is the total amount of light they emit, not their brightness and not the light level on a surface. Typical
indoor lamps have light output ranging from 50 to 10,000 lumens. Lumen value is used for purchasing and
comparing lamps and their outputs. Lumen output of a lamp is not related to the light distribution pattern of
a lamp.
Luminaries: a complete lighting unit consisting of a lamp or lamps together with the housing designed to
distribute the light, position and protect the lamps, and connect the lamps to the power supply.
Manual (non-automatic): requiring personal intervention for control. Non-automatic does not necessarily
imply a manual controller, only that personal intervention is necessary.
Manufacturer: the company engaged in the original production and assembly of products or equipment
or a company that purchases such products and equipment manufactured in accordance with company
specifications.
Mean temperature: one-half the sum of the minimum daily temperature and maximum daily temperature.
Mechanical cooling: reducing the temperature of a gas or liquid by using vapor compression, absorption, and
desiccant dehumidification combined with evaporative cooling, or another energy-driven thermodynamic cycle.
Indirect of direct evaporative cooling alone is not considered mechanical cooling.
Metering: instruments that measure electric voltage, current, power, etc.
Multifamily high-rise: multifamily structures of four or more stories above grade
Multifamily low-rise: multifamily structures of three or less stories above grade
Multiplication factor: indicates the relative reduction in annual solar cooling load from overhangs and/or side
fins with given projection factors, relative to the respective horizontal and vertical fenestration dimensions.

Non-automatic: See definition of “manual.”
Occupancy sensor: a device that detects the presence or absence of people within an area and causes lighting,
equipment, or appliances to be regulated accordingly.
Opaque: all areas in the building envelope, except fenestration and building service openings such as vents and
grilles.
Orientation: the direction an envelope element faces, i.e., the direction of a vector perpendicular to and
pointing away from the surface outside of the element. For vertical fenestration, the two categories are north-
oriented and all other.
Outdoor (outside) air: air that is outside the building envelope or is taken from the outside the building that
has not been previously circulated through the building.
Overcurrent: any current in excess of the rated current of the equipment of the capacity of the conductor. It
may result from overload, short circuit, or ground fault.
PackagedTerminalAirConditioner(PTAC):afactory-selectedwallsleeveandseparateunencasedcombination
of heating and cooling components, assemblies, or sections. It may include heating capability by hot water, steam,
or electricity, and is intended for mounting through the wall to service a single room or zone.
Party wall: a firewall on an interior lot line used or adapted for joint service between two buildings.
Permanently installed: equipment that is fixed in place and is not portable or movable.
Plenum: a compartment or chamber to which one or more ducts are connected, that forms a part of the air
distribution system, and that is not used for occupancy or storage. A plenum often is formed in part or in total
by portions for the building.
Pool: any structure, basin, or tank containing an artificial body of water for swimming, diving, or recreational
bathing. The terms include, but are not limited to, swimming pool, whirlpool, spa, hot tub.
Process load: the load on a building resulting from the consumption or release of process energy.
Projection factor, overhang: the ratio of the horizontal depth of the external shading projection divided by
the sum of the height of the fenestration and the distance from the top of the fenestration to the bottom of
the farthest point of the external shading projection, in consistent units.
Projection factor, sidefin: the ratio of the horizontal depth of the external shading projection divided by the
distance from the window jamb to the farthest point of the external shading projection, in consistent units.
R-value (thermal resistance): the reciprocal of the time rate of heat flow through a unit area induced by

a unit temperature difference between two defined surfaces of material or construction under steady-state
conditions. Units of R are m2
·K/W (h·ft2
·°F/Btu). For the prescriptive building envelope option, R-value is for
the insulation alone and does not include building materials or air films.
Readily accessible: capable of being reached quickly for operation, renewal, or inspections without requiring
those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders,
chairs, etc. In public facilities, accessibility may be limited to certified personnel through locking covers or by
placing equipment in locked rooms.
Recirculating system: a domestic or service hot water distribution system that includes a close circulation
circuit designed to maintain usage temperatures in hot water pipes near terminal devices (e.g., lavatory faucets,
shower heads) in order to reduce the time required to obtain hot water when the terminal device valve is
opened. The motive force for circulation is either natural (due to water density variations with temperature) or
mechanical (recirculation pump).
Reflectance: the ratio of the light reflected by a surface to the light incident upon it
Resistance, electric: the property of an electric circuit or of any object used as part of an electric circuit that
determines for a given circuit the rate at which electric energy is converted into heat or radiant energy and that
has a value such that the product of the resistance and the square of the current gives the rate of conversion
of energy
Reset: automatic adjustment of the controller set point to a higher or lower value
Residential: spaces in buildings used primarily for living and sleeping. Residential spaces include, but are not
limited to, dwelling units, hotel/motel guest rooms, dormitories, nursing homes, patient rooms in hospitals,
lodging houses, fraternity/sorority houses, hostels, prisons, and fire stations.
Return Air: air from the conditioned area that is returned to the conditioning equipment for reconditioning.
The air may return to the system through a series of ducts, plenums, and airshafts.
Roof: the upper portion of the building envelope, including opaque areas and fenestration, that is horizontal or
tilted at an angle of less than 60° from horizontal
Roof area, gross: the area of the roof measured from the exterior faces of walls or from the centerline of
party walls
Service: the equipment for delivering energy from the supply or distribution system to the premises served
Service water heating: heating water for domestic or commercial purposes other than space heating and
process requirements
Set point: point at which the desired temperature (°C) of the heated or cooled space is set
Shading Coefficient (SC): the ratio of solar heat gain at normal incidence through glazing to that occurring through
3 mm (1/8 in) thick clear, double-strength glass. Shading coefficient, as used herein, does not include interior, exterior,
or integral shading devices
Simulation program: a computer program that is capable of simulating the energy performance of building
systems
Single-zone system: an HVAC system serving a single HVAC zone
Site-recovered energy: waste energy recovered at the building site that is used to offset consumption of
purchased fuel or electrical energy supplies
Skylight roof ratio (SRR): the ratio of the total skylight area of the roof, measured to the outside of the
frame, to the gross exterior roof.

Slab-on-grade floor: that portion of a slab floor of the building envelope that is in contact with ground
and that is either above grade or is less than or equal to 24 in below the final elevation of the nearest exterior
grade
Solar energy source: source of thermal, chemical, or electrical energy derived from direction conversion of
incident solar radiation at the building site.
Solar Heat Gain Coefficient (SHGC): the ratio of the solar heat gain entering the space through the
fenestration area to the incident solar radiation, typically ranging from 0.9 to 0.1, where lower values indicate
lower solar gain. Solar heat gain includes directly transmitted solar heat and absorbed solar radiation, which is
then reradiated, conducted, or convected into the space.
Space: an enclosed space within a building. The classifications of spaces are as follows for the purpose of
determining building envelope requirements.
Conditioned space: a cooled space, heated space, or directly conditioned space.
Semi-heated space: an enclosed space within a building that is heated by a heating system whose output
capacity is greater or equal to 10.7 W/m2
(3.4 Btu/h-ft2
) of floor area but is not a conditioned space.
Enclosed Space: space within a building that is not conditioned space or a semi-heated space. Crawlspaces,
attics, and parking garages with natural or mechanical ventilation are not considered enclosed spaces.
Standard Design: a computer representation of a hypothetical design based on the actual Proposed Design as per
Appendix B– Whole Building Performance Method
Story: portion of a building that is between one finished floor level and the next higher finished floor level or
the roof, provided, however, that a basement or cellar shall not be considered a story.
Supply Air: air being conveyed to a conditioned area through ducts or plenums from a heat exchanger of a
heating, cooling, absorption, or evaporative cooling system. Supply air is commonly considered air delivered
to a space by a space-conditioning system. Depending on space requirements, the supply may be either heated,
cooled or neutral.
System: a combination of equipment and auxiliary devices (e.g., controls, accessories, interconnecting means,
and terminal elements) by which energy is transformed so it performs a specific function such as HVAC, service
water heating, or lighting.
System, existing: a system or systems previously installed in an existing building.
Terminal: a device by which energy form a system is finally delivered, e.g., registers, diffusers, lighting fixtures,
faucets, etc.
Thermal block: a collection of one or more HVAC zones grouped together for simulation purposes. Spaces
need not be contiguous to be combined within a single thermal block.
Thermal Zone: a term used in energy simulation to represent area catered to by one air conditioning unit. With
the help of the “zoning” building plans are simplified to reduce the modeler’s work. Normally, within one zone
usage pattern, set point temperature and other conditions are identical. Building spaces that would experience
similar heating and cooling loads are generally grouped under one zone.
Thermostat: an automatic control device used to maintain temperature at a fixed or adjustable set point.
Tinted: (as applied to fenestration) bronze, green, or grey coloring that is integral with the glazing material.
Tinting does not include surface applied films such as reflective coatings, applied either in the field or during
the manufacturing process.
Ton: one ton of cooling is the amount of heat absorbed by one ton of ice melting in one day, which is
equivalent to 3.5136 KW or 3.516 thermal kW.

Transformer: a piece of electrical equipment used to convert electric power from one voltage to another
voltage.
U-factor (Thermal Transmittance): heat transmission in unit time through unit area of a material or
construction and the boundary air films, induced by unit temperature difference between the environments on
each side. Units of U are W/m2
-°C (Btu/h ft2
°F).
Variable Air Volume (VAV) system: HVAC system that controls the dry-bulb temperature within a space by
varying the volumetric flow of heated or cooled supply air to the space
Vent damper: a device intended for installation in the venting system or an individual, automatically operated,
fossil fuel-fired appliance in the outlet or downstream of the appliance draft control device, which is designed
to automatically open the venting system when the appliance is in operation and to automatically close off the
venting system when the appliance is in standby or shutdown condition.
Ventilation: the process of supplying or removing air by natural or mechanical means to or from any space.
Such air is not required to have been conditioned.
Visible Light Transmittance (VLT): also known as the Visible Transmittance, is an optical property of a light
transmitting material (e.g. window glazing, translucent sheet, etc.) that indicates the amount of visible light transmitted
of the total incident light.
Wall: that portion of the building envelope, including opaque area and fenestration, that is vertical or tilted at
an angle of 60° from horizontal or greater. This includes above and below-grade walls, between floor spandrels,
peripheral edges of floors, and foundation walls.
Wall, above grade: a wall that is not below grade
Wall, below grade: that portion of a wall in the building envelope that is entirely below the finish grade and
in contact with the ground
Wall area, gross: the overall area off a wall including openings such as windows and doors, measured
horizontally from outside surface to outside service and measured vertically from the top of the floor to the top
of the roof. If roof insulation is installed at the ceiling level rather than the roof, then the vertical measurement
is made to the top of the ceiling. (Note that does not allow roof insulation to be located on a suspended ceiling
with removable ceiling panels.) The gross wall area includes the area between the ceiling and the floor for multi-
story buildings.
Water heater: vessel in which water is heated and is withdrawn for use external to the system.
Weather stripping: Materials, such as a strip of fabric, plastic, rubber or metal, or a device used to seal the
openings, gaps or cracks of venting window and door units to prevent water and air infiltration.

Window Wall Ratio (WWR): the ratio of vertical fenestration area to gross exterior wall area. Gross exterior
wall area is measured horizontally from the exterior surface; it is measured vertically from the top of the floor
to the bottom of the roof.
Zone, HVAC: A space or group of spaces within a building with heating and cooling requirements that are
sufficiently similar so that desired conditions (e.g., temperature) can be maintained throughout using a single
sensor (e.g., thermostat or temperature sensor).
Abbreviations and Acronyms9.3
AFUE Annual fuel utilization efficiency
ANSI American National Standards Institute
ARI Air-Conditioning and Refrigeration Institute
ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers
ASTM American Society for Testing and Materials
BIS Bureau of Indian Standards
Btu British thermal unit
Btu/h British thermal units per hour
Btu/ft2
°F British thermal units per square foot per degree Fahrenheit
Btu/h ft2
British thermal units per hour per square foot
Btu/h ft °F British thermal units per lineal foot per degree Fahrenheit
Btu/h ft2
°F British thermal units per hour per square foot per degree Fahrenheit
C Celsius
cfm Cubic feet per minute
cm Centimeter
COP Coefficient of Performance
DOE Department of Energy, U.S.
EER Energy Efficiency Ratio

EC Act 2001 Energy Conservation Act 2001
EF Energy Factor
F Fahrenheit
ft Foot
h Hour
HC Heat capacity
h ft2
°F/Btu Hour per square foot per degree Fahrenheit per British thermal unit
h m2
·K/W Hour per square meter per degree Celsius per Watt
hp Horsepower
HSPF Heating seasonal performance factor
HVAC Heating, Ventilation, and Air Conditioning
I-P Inch-pound
in. Inch
IPLV Integrated part-load value
ISHRAE Indian Society of Heating, Refrigeration and Air-conditioning Engineers
kVA Kilovolt-ampere
kW kilowatt
kWh kilowatt-hour
LE Lighting efficacy
lin Linear
lin ft Linear foot
lin m Linear meter
lm Lumen
LPD Lighting Power Density
m Meter
mm Millimeter
NAECA National Appliance Energy Conservation Act
PF Projection factor
PTAC Packaged terminal air conditioner
R R-value (thermal resistance)
SC Shading Coefficient
SHGC Solar heat gain coefficient
SL Standby loss

VAV Variable air volume
VLT Visible light transmission
W Watt
W/ft2
Watts per square feet
W/m2
Watts per square meter
W/m2
·K Watts per square meter per degree Celsius
W/m2
Watts per hour per square meter
W/m·K Watts per lineal meter per degree Celsius
W/m2
·K Watts per hour per square meter per degree Celsius
Wh Watthour

Appendix B: Whole Building Performance Method
Energy Conservation Building Code (ECBC) User Guide B.1
APPENDIX B: Whole Building Performance
Method1
General10.1
Whole building energy simulation analysis is used to predict the annual energy performance of a building
design. The analysis is carried out by first developing a detailed building energy simulation model. The
simulation program is then used to test the thermal response, and to calculate the energy use of the building
model using a weather data file to capture the climatic impact on the building. This type of analysis is referred
to as the “Whole Building Performance” (WBP) method.
Benefits
Whole building energy simulation is currently the most sophisticated way of analyzing the impact of energy
efficiency measures in an integrated manner. It is an alternative to the prescriptive requirements contained in §4
to §8 of ECBC. The impact of changing any one of the myriad parameters affecting energy performance of the
building design being modeled can be predicted using this method. This is particularly useful for studying the
impact of combinations of energy efficiency measures that may lead to non-linear building energy outcomes.
For example, electric lights produce light and heat inside a space. Calculating the electrical consumption for the
electric lights is not very difficult, as long as one knows how many lights there are, what their heat output is, and
how many hours they run. One does not need a simulation model to predict this outcome. However, the heat
generated by electric lighting has to be removed by the HVAC systems in a warm or hot climate. Calculating the
reduction in energy used by the HVAC systems due to the use of a more efficient electric lighting system is not
recommended through manual calculations.
This computation becomes significantly more complex if the design team decides to employ a daylight linked
electric lighting system. Such a system is designed to reduce light (and heat output) in a space when enough
daylight is available. This non-linear relationship impacts the electric energy input to the lighting system, and the
heat removed by the HVAC system. At this time, predicting the integrated energy performance resulting from
complex energy efficiency strategies cannot be studied reliably by any other means except the use of a whole
building energy simulation analysis.
Once the model is completed and a base run is established, carrying out multiple runs to test alternate design
options involves less effort on the part of the analyst, although there could still be substantial computer
run time involved. Whole building energy simulation is increasingly being used for testing compliance with
various building energy codes and sustainability rating tools such as LEED and GRIHA. Technically reliable
and verifiable energy simulation programs satisfying the minimum modeling capabilities (specified in §10.2.1)
should be used for compliance using this verification method.
Scope10.1.1
In general, the WBP method may be used to show compliance with the ECBC for any project at the designer’s
discretion, subject to the following caveats and exceptions.
No HVAC System
Use of the WBP method requires knowledge of the proposed HVAC system in order to create the Standard
Design. Buildings with no HVAC system cannot use the WBP Method. In the case of a shell building, which
might become conditioned in the future, trade-offs may still be made within the envelope system.
1 This chapter has been adapted from Appendix G and ECB chapter of ASHRAE User Manual

Alterations to Existing Buildings
When the WBP method is used for an alteration of an existing building, some special rules apply. The WBP
method is optional for this purpose; designers may use the calculation acceptable to the Authority Having
Jurisdiction. Unless a building component is being altered, the Proposed Design and the Standard Design are identical
for that component. Portions of the building that are being replaced shall be treated as new systems and these
systems in the Standard Design shall be representative of the requirements in the ECBC.
Alterations and Additions
The basic rules for alterations and additions are discussed in the Administration and Enforcement Section (§3)
of the ECBC User Guide. There are some more rules that apply to cases where it is undesirable either to treat
the addition as a stand-alone building or to fully model the entire existing building. It is often necessary with
additions or alterations to model at least part of the existing building. For instance, if the existing building’s
HVAC system is being extended to serve the new construction, then that system needs to be fully modeled
in order to account for its energy performance. If, however, this system only serves a portion of the existing
building and only part of that building is affected by the new work, then it is not necessary to model the entire
existing building.
Parts of Existing Buildings
The rules for excluding parts of the existing building are as follows:
If there is new construction that comes under the ECBC scope and it is part of the existing building•
but will be excluded from the Proposed Design, then those parts must comply with the Code’s applicable
prescriptive requirements.
The excluded parts of the existing building must be served by HVAC systems that are completely•
independent of the systems or building components being modeled for the Proposed Building.
There should not be any significant energy flows between the excluded parts of the building and•
the modeled parts. Rephrasing, the design space temperature, HVAC system operating set points, and
operating and occupancy schedules on both sides of the boundary between the included and excluded
parts must be the same. If the excluded portion of the building is a refrigerated warehouse and the
included portion is an office, this condition would not be met, because there would be significant
energy flows between them.
Compliance10.1.2
Compliance of the Proposed Design with the requirements of the ECBC Whole Building Performance Method
consists of the following steps:
Developing a• Standard Design simulation model
Carrying out a valid energy simulation run using the• Standard Design to predict its annual energy use
Developing the• Proposed Design simulation model for which compliance is being sought
Carrying out a valid energy simulation run for the• Proposed Design model and ensuring that the predicted
annual energy use is less than or equal to the energy use in Standard Design
The major consideration for generating the Standard Design simulation model is that it complies with the minimum
performance requirements specified in the ECBC.
Much of the remainder of this chapter is addressed towards the development of the Standard and Proposed
Designs. The following sections describe how decisions are to be taken for each of the two designs, and how
these two simulation runs are to be done, but the following rules always apply:
Mandatory provisions of the Code mentioned in §4 through section §8 are met•
Both simulation runs must use the same simulation program•

Both simulation runs must use the same climate data•
Both simulation runs must use the same schedules of operation•
These rules ensure a fair comparison between the two runs, without introducing extraneous differences. For
instance, if the runs used different simulation programs, then some portion of the differences between the
resulting energy consumption would be due to differences in algorithms or calculation methodologies making
it difficult to evaluate the impact of the two designs on energy use.
The WBP method provides the building owner and design team with the flexibility to try out different design
options, provided the end result is a building that does not have higher annual energy consumption than if it
would have met all the prescriptive requirements. For example, the owner may decide to invest in a more efficient
lighting system in place of larger glazing areas or invest in high performance glazing to avoid the cost of installing
an economizer and get the benefits of daylighting.
Annual Energy Use10.1.3
Annual energy use for the purposes of the whole building performance method shall be calculated in kilowatt-
hours (kWh) of electricity use per year. Energy sources other than electricity which are used in the building shall
be converted to kWh of electric energy at the rate of 0.75 kWh per mega Joule.
Trade-offs Limited to Building Permit10.1.4
The whole building performance method may be used for building permit applications that include less than the
whole building; however, any design parameters that are not part of the building permit application shall be identical
for both the Proposed Design and the Standard Design. Future improvements to the building shall comply with both the
mandatory and prescriptive requirements.
Documentation Requirements10.1.5
Compliance shall be documented and submitted to the Authority Having Jurisdiction. The information submitted
shall include the following:
The annual energy use for thea. Proposed Design and the Standard Design.
A list of the energy-related building features in theb. Proposed Design that is different from the Standard
Design.
The input and output report (s) from the simulation program including a breakdown of energy usagec.
by at least the following components: lights, internal equipment loads, service water heating equipment,
space heating equipment, space cooling and heat rejection equipment, fans, and other HVAC equipment
(such as pumps). The output reports shall also show the amount of time any loads are not met by the
HVAC system for both the Proposed Design and Standard Design.2
An explanation of any error messages noted in the simulation program output.d.
Simulation General Requirements10.2
Energy Simulation Program10.2.1
WBP method uses the output of a simulation program to demonstrate that the Proposed Design complies with the
ECBC. In order to make sure that these calculations are sufficiently accurate for the purposes of the Code, a
series of requirements have been set. The most basic requirement is that the simulation program be a computer-
based program designed to analyze energy consumption in buildings, and that it has the capability to model the
Proposed Design’s features. A building energy simulation model comprises of:
Detailed description of the building geometry and materials of construction•
2 In order to show compliance using WBP method, WBP compliance forms (included in Appendix G) must be completed and submitted.

Description of the internal loads in the building, e.g., lighting, equipment and people•
Description of the environmental control systems that operate to maintain comfortable conditions•
Description of schedules and controls to characterize the internal loads and environmental control•
systems
Building Modela)
Much of the effort in developing the model for an energy simulation analysis is in describing building geometry.
This includes
Describing the overall building envelope and geometry, ie., number of floors, orientation•
Describing physical and thermal properties for the construction of each building element•
Describing the location, size and the thermal, optical and solar properties of windows•
Describing permanent• shading devices attached to the building, automatic window blinds and details
of their operation
Describing objects that might cast shadow on the building being simulated, e.g., surrounding buildings•
Describing spaces or “thermal zones” and their relative location, and relationship with the HVAC•
system design for the building
Minimum Modeling Capabilitiesb)
This defines the minimum set of capabilities for WBP method simulation programs. These have been broadly
defined to allow all complying programs to be considered for approval by the Authority Having Jurisdiction, while
eliminating programs that would not be able to adequately account for the energy performance of building
features important under the Code. These minimum capabilities are:
Approved Simulation Program:• The simulation program should be subjected to the International
Energy Agency BESTEST (Building Energy Simulation Test and Diagnostic Method) or the ANSI/
ASHRAE Standard 140-2004, Standard Method of Test for the Evaluation of Building Energy Analysis
Computer Programs.
Minimum Hours per Year:• Programs must be able to model energy flows on an hourly basis for the
entire year (8,760 hours).
Hourly Variations:• Building loads and system operations vary hour-by-hour, and their interactions
have a great influence on building energy performance. Approved programs must have the capability to
model hourly variations – and to establish separately designed schedules of operation for each day of
the week and for holidays – for occupancy, lighting power, miscellaneous equipment power, thermostat
set points, and HVAC system operation.
Thermal Mass Effects:• A building’s ability to absorb and hold heat varies with the type of construction
and with the system and ventilation characteristics. This affects the timing and magnitude of loads
handled by the HVAC system. Simulation programs must be able to model these thermal mass effects.
Number of Thermal Zones:• There are multiple thermal zones in all but the simplest buildings, and
they experience different load patterns. Approved programs must be able to model at least 10 thermal
zones; many simulation programs can handle far greater number of zones.
Part-Load Performance:• Mechanical equipment seldom experiences full-load operating conditions,
so the performance of this equipment under part-load conditions is important. Approved programs
must incorporate part-load performance curves in their calculations.
Correction Curves:• The efficiency of the mechanical equipment varies depending on temperature and
humidity conditions. Approved programs must incorporate efficiency correction curves for mechanical
heating and cooling equipment.

Economizers:• Economizer cooling is an important efficiency measure under the Standard. Approved
programs must have the capability to model both airside and waterside economizers with integrated
control.
Design Load Calculations:• Approved programs must be capable of performing design load
calculations to determine required HVAC equipment capacities and air and water flow rates for both the
Proposed Design and the Standard Design. This is to ensure that the systems in both design simulations are
properly sized, which avoids the problem of differing part-load performance characteristics between
the two designs.
Modeling Exceptionsc)
All the energy systems of the Proposed Design must be modeled. The Standard Design, however, does have some
exceptions that may be applied only in rare, special cases. It is allowable to exclude some components or systems
of the Proposed Design provided they do not affect the energy usage of the other systems being modeled for
trade-off purposes. For example, if the service hot water heating system is not located in the conditioned space,
and if it is not generating significant heat gains that affect the HVAC system, then it may be ignored in the
model. All systems that are excluded on this basis, however, must still meet the prescriptive requirements that
apply to them. This exception can help to simplify the modeling somewhat, but only in ways that will not affect
the accuracy of the WBP method calculations.
Limitations of the Simulation Programd)
There may also be cases where the simulation program lacks modeling capabilities needed to fully model
a component or system of the Proposed Design. If this means that a reasonable calculation of the proposed
building cannot be made, then the best solution is to seek a different program that has the needed capabilities.
One alternative is to ignore the system in the model, provided this does not affect the modeling of energy
consumption measures, described in the previous section. A second alternative is to apply engineering judgment
and to model the component or system using a thermodynamically similar model that is within the capabilities
of the program being used. This requires a thorough understanding of the algorithms of the simulation
program and the thermodynamic characteristics of the component being modeled, but in many cases, it can
be accomplished without compromising accuracy. It makes little sense, though, to use an alternate program for
a component if it means losing the interactive capabilities of the hourly modeling tool. Consequently, this is
generally not recommended. A third alternative is to simply model the system or component as if it were the
base case system defined for the Standard Design. Of course, this alternative is only allowable when the system
or component meets the prescriptive requirements of the ECBC. Also, this alternative is not preferred, as the
intent is to model the actual Proposed Design. The general rule, therefore, is if a simulation program can’t model
a component, then the component must not be given any energy saving benefits.
Climate Data Requirements10.2.2
A reference climate data file for the location being tested or a prescribed equivalent should be used for the
analysis. The ISHRAE database of weather files developed for energy simulation is the primary dataset for this
type of analysis.
Compliance Calculations10.2.3
On-Site Renewable or Site-Recovered Energya)
There is a special case for calculating the design energy consumption for buildings that have on-site renewable
energy sources or site recovered energy. For example, a building may have a solar thermal array, photovoltaic
panels, a geothermal energy source, or a building with substantial refrigeration loads may recover heat from
the condenser to meet service water heating loads. If either renewable or recovered energy is available at the
site, it is considered free energy by the WBP method, and that energy is not included in the design energy
consumption, provided that it is not required by any of the prescriptive requirements in ECBC. For the Standard
Design calculations, the loads met by renewable or recovered energy are considered to be served by the backup

energy source. For example, where recovered energy is used to heat water, then the backup water heater would
be assumed to supply all the hot water for the Standard Design, and that would be part of the Standard Design
method. If no backup energy source is specified for the Proposed Design, then the source is assumed to be
electricity in the Standard Design.
Exceptional Calculation Methodb)
As newer technologies become available, there may be cases where none of the existing simulation programs
can adequately model the energy performance of these technologies. The WBP method allows users to use
exceptional calculations, provided the nature of the exceptional method is open-ended; however, the burden is
on the applicant to demonstrate that the method is reasonable, accurate, well founded, and not in contradiction
with the rules of the WBP Method. The applicant must describe the theoretical basis for the exceptional
method and must provide empirical evidence that the method accurately represents the energy performance of
the design, material, or device.
Disclaimerc)
It is important for users of the WBP method, as well as the owners of the proposed buildings, to understand
the WBP Method’s intent and limitations. It is intended to provide a fair method of comparison between the
estimated annual energy consumption of the Proposed Design and the Standard Design for purposes of compliance
with the Code. The WBP Method is not intended to provide the most accurate prediction of actual energy
consumption for the building as it is actually built. Although the designer is expected to model the future use
of the building as closely as possible, there are many reasons why the actual building performance may differ
from the design energy consumption. These include:
Variations in Operation and Occupancy:• The actual schedules of operation and occupancy may
differ from those assumed in the WBP analysis.
Variations in Control and Maintenance:• The building’s energy systems may be controlled differently
than assumed; the equipment may not be set up or maintained properly.
Variations in Weather:• The simulation runs use weather data that may not match the actual weather
conditions; further, there is variability in weather conditions from year-to-year.
Energy Uses not Included:• The WBP method under certain conditions, may not require all building
energy uses to be included in calculating the design energy consumption. Sometimes, there is additional
energy-using equipment that is added to a building after it is built.
Precision of the Simulation Program:• Even the most sophisticated simulation programs approximate
the actual energy flows and consumption in a building; further, the energy analyst will usually make
simplifying assumptions. Both can be sources of error in the predictions of energy consumption.
Calculating the Energy Consumption of the10.3 Proposed Design
and the Standard Design
The simulation model for calculating the10.3.1 Proposed Design and the
Standard Design shall be developed in accordance with the require-
ments in Table 10.1

:ModelingRequirementsforCalculatingProposedandStandardDesignTable10.13
CaseProposedDesignStandardDesign
DesignModelThesimulationmodelofthe(a) ProposedDesignshallbeconsistentwiththedesign
documents,includingproperaccountingoffenestrationandopaqueenvelope
typesandarea;interiorlightingpowerandcontrols;HVACsystemtypes,sizes,and
controls;andservicewaterheatingsystemsandcontrols.
Whenthewholebuildingperformancemethodisappliedtobuildingsinwhichenergy-(b)
relatedfeatureshavenotyetbeendesigned(e.g.,alightingsystem),thoseyet-to-be-
designedfeaturesshallbedescribedintheProposedDesignsothattheyminimallycomply
withapplicablemandatoryandprescriptiverequirementsfrom§4through§8.
Allconditionedspacesinthe(c) ProposedDesignshallbesimulatedasbeingbothheatedand
cooledevenifnoheatingorcoolingsystemistobeinstalled,andtemperatureandhumid-
itycontrolsetpointsandschedulesshallbethesameforProposedandStandardDesigns.
Allunconditionedandnaturallyventilatedoccupiedspacesinthe(d) ProposedDesign
shallbesimulatedandtemperatureandhumiditycontrolsetpointsshallbespeci-
fiedperNationalBuildingCode(2005)orASHRAE55(2004).
TheStandardDesignsshallbedevelopedbymodifyingtheProposedDesign
asdescribedinthistable.Exceptasspecificallyinstructedinthistable,
allbuildingsystemsandequipmentshallbemodeledidenticallyinthe
StandardDesignsandProposedDesign.
Additionsand
Alterations
Itisacceptabletopredictperformanceusingbuildingmodelsthatexcludepartsofthe
existingbuildingprovidedthatallofthefollowingconditionsaremet:
Worktobeperformedinexcludedpartsofthebuildingshallmeettherequire-(a)
mentsof§4through§8.
ExcludedpartsofthebuildingareservedbyHVACsystemsthatareentirelyseparate(b)
fromthoseservingpartsofthebuildingthatareincludedinthebuildingmodel.
DesignspacetemperatureandHVACsystemoperatingsetpointsandschedulesoneitherside(c)
oftheboundarybetweenincludedandexcludedpartsofthebuildingareessentiallythesame.
SameasProposedDesign.
SpaceUse
Classification
Thebuildingtypeorspacetypeclassificationsshallbechoseninaccordancewith§7.3.2or§7.3.3.
Morethanonebuildingtypecategorymaybeusedinabuildingifitisamixed-usefacility.
SameasProposedDesign
SchedulesSchedulescapableofmodelinghourlyvariationsinoccupancy,lightingpower,
miscellaneousequipmentpower,thermostatsetpoints,andHVACsystemoperation
shallbeused.Theschedulesshallbetypicaloftheproposedbuildingtypeasdetermined
andapprovedbytheAuthorityHavingJurisdiction.
HVACFanSchedulesthatprovidesoutdoorairforventilationshallruncontinuouslywheneverspacesare
occupiedandshallbecycledonandofftomeetheatingandcoolingloadsduringunoccupiedhours.
Exceptions:
Wherenoheatingand/orcoolingsystemistobeinstalledandaheatingorcoolingsystem(a)
isbeingsimulatedonlytomeettherequirementsdescribedinthistable,heatingand/or
coolingsystemfansshallnotbesimulatedasrunningcontinuouslyduringoccupiedhours
butshallbecycledonandofftomeetheatingandcoolingloadsduringallhours.
HVACfansshallremainonduringoccupiedandunoccupiedhoursinspacesthathave(b)
healthandsafetymandatedminimumventilationrequirementsduringunoccupiedhours.
3 ThetablehasbeenenhancetoprovideadditionaldetailstodevelopStandardandProposedDesign.

BuildingEn-
velope
AllcomponentsofthebuildingenvelopeintheProposedDesignshallbemodeledas
shownonarchitecturaldrawingsorasinstalledforexistingbuildingenvelopes.
Exceptions:Thefollowingbuildingelementsarepermittedtodifferfromarchitectural
drawings.
Anyenvelopeassemblythatcoverslessthan5%ofthetotalareaofthatassembly(a)
type(e.g.,exteriorwalls)neednotbeseparatelydescribed.Ifnotseparatelyde-
scribed,theareaofanenvelopeassemblymustbeaddedtotheareaoftheadjacent
assemblyofthatsametype.
Exteriorsurfaceswhoseazimuthorientationandtiltdifferbynomorethan45(b)
degreesandareotherwisethesamemaybedescribedaseitherasinglesurfaceor
byusingmultipliers.
Forexteriorroofsotherthanroofswithventilatedattics,thereflectanceandemit-(c)
tanceoftheroofsurfaceshallbemodeled.Forexteriorroofs,theroofsurfacemay
bemodeledwithareflectanceof0.45ifthereflectanceoftheProposedDesignroof
isgreaterthan0.70anditsemittanceisgreaterthan0.75.Allotherroofsurfaces
shallbemodeledwithareflectanceof0.30.Thereflectanceandemittanceshallbe
testedinaccordancewith§4.3.1.1.
Manuallyoperatedfenestrationshadingdevicessuchasblindsorshadesshallnot(d)
bemodeled.Permanentshadingdevicessuchasfins,overhangs,andlightshelves
shallbemodeled.
TheStandardDesignsshallhaveidenticalconditionedfloorareaandidenticalexterior
dimensionsandorientationsastheProposedDesign,exceptasnotedbelow.
Orientation:(a) Thestandardbuildingperformanceshallbegeneratedbysimulatingthebuilding
withitsactualorientationandagainafterrotatingtheentirebuilding90,180,270degrees,then
averagingtheresults.Thebuildingshallbemodeledsothatitdoesnotshadeitself.Opaque
assembliessuchasroof,floors,doors,andwallsshallbemodeledashavingthesameheat
capacityastheProposedDesignandU-factorcomplywithrequirementsof§4.3.1and§4.3.2.
Fenestration(b) areasshallequalthatintheProposedDesignor40%ofgrossabovegradewall
area,whicheverissmaller,andshallbedistributeduniformlyinhorizontalbandsacross
thefourorientations.Noshadingprojectionsaretobemodeled;fenestrationshallbe
assumedtobeflushwiththeexteriorwallorroof.Manuallyoperatedfenestrationshading
devicessuchasblindsorshadesshallnotbemodeled.FenestrationU-factorshallcomply
withTable4.3,andtheSHGCshallcomplywithTable4.3and4.4oftheCode.
RoofAlbedo:(c) Allroofsurfacesshallbemodeledwithareflectivityof0.30.
Skylights(d) :SkylightareashallbeequaltothatintheProposedDesignor5%ofthegross
roofareathatispartofthebuildingenvelope,whicheverissmaller.Iftheskylight
areaoftheProposedDesignisgreaterthan5%ofthegrossroofarea,baselineskylight
areashallbedecreasedbyanidenticalpercentageinallroofcomponentsinwhich
skylightsarelocatedtoreachthe5%skylight-to-roofratio.Skylightorientationand
tiltshallbethesameasintheProposedDesign.SkylightU-factorandSHGCproperties
shallmatchtheappropriaterequirementsforclimateandorientation.
ExistingBuildings.(e) Forexistingbuildingenvelopes,theStandardDesignsshallreflectexisting
conditionspriortoanyrevisionsthatarepartofthescopeofworkbeingevaluated.
LightingLightingpowerintheProposedDesignshallbedeterminedasfollows:
Whereacompletelightingsystemexists,theactuallightingpowershallbeusedin(a)
themodel.
Wherealightingsystemhasbeendesigned,theLPDshouldmatchthedesign(b)
whichshallbedeterminedinaccordancewitheither§7.3.2or§7.3.3.
Wherenolightingexistsorisspecified,lightingpowershallbedeterminedinac-(c)
cordancewiththe§7.3.2fortheappropriatebuildingtype.
Lightingsystempowershallincludealllightingsystemcomponentsshownorprovided(d)
foronplans(includinglamps,ballasts,taskfixtures,andfurniture-mountedfixtures).
Exception:Formultifamilydwellingunits,hotel/motelguestrooms,andother(e)
spacesinwhichlightingsystemsareconnectedviareceptaclesandarenotshown
orprovidedforonbuildingplans,assumeidenticallightingpowerfortheProposed
andStandardDesignsinthesimulations.
Lightingpowerforparkinggaragesandbuildingfacadesshallbemodeled.(f)
Creditmaybetakenfortheuseofautomaticcontrolsfordaylightutilizationbut(g)
onlyiftheiroperationiseithermodeleddirectlyinthebuildingsimulationor
modeledinthebuildingsimulationthroughscheduleadjustmentsdeterminedbya
separatedaylightinganalysisapprovedbytheAuthorityHavingJurisdiction.
LightingpowerintheStandardDesignsshallbedeterminedusingthesamecategorization
procedure(buildingareaorspacefunction)andcategoriesastheProposedDesignwith
lightingpowersetequaltothemaximumallowedforthecorrespondingmethodand
categoryineither§7.3.2or§7.3.3.Powerforfixturesnotincludedinthelightingpower
densitycalculationshallbemodeledidenticallyintheProposedandStandardDesign.
Noautomaticlightingcontrols(e.g.programmableorautomaticcontrolsfordaylight
utilization)shallbemodeledintheStandardDesign,asthelightingschedulesusedare
understoodtoreflectthemandatorycontrolrequirementsintheCode.

HVACZones
Designed
WhereHVACzonesaredefinedonHVACdesigndrawings,eachHVACzoneshallbe
modeledasaseparatethermalzone.
Exception:DifferentHVACzonesmaybecombinedtocreateasinglethermalzone,
providedthatallofthefollowingconditionsaremet:
Thespaceuseclassificationisthesamethroughoutthethermalzone.(a)
AllHVACzonesinthethermalzonethatareadjacenttoglazedexteriorwallsface(b)
thesameorientationortheirorientationsvarybylessthan45degrees.
AllofthezonesareservedbythesameHVACsystemorbythesamekindof(c)
HVACsystem.
HVACZones
NotDesigned
WheretheHVACzonesandsystemshavenotyetbeendesigned,thermalzonesshallbe
definedbasedonsimilarinternalloaddensities,occupancy,lighting,thermalandspace
temperatureschedules,andincombinationwiththefollowingguidelines:
Separatethermalzonesshallbeassumedforinteriorandperimeterspaces.Interior(a)
spacesshallbethoselocatedgreaterthan5mfromanexteriorwall.Perimeter
spacesshallbethoselocatedwithin5mofanexteriorwall.
Separatethermalzonesshallbeassumedforspacesadjacenttoglazedexterior(b)
walls;aseparatezoneshallbeprovidedforeachorientation,exceptthatorienta-
tionsthatdifferbylessthan45degreesmaybeconsideredtobethesameorienta-
tion.Eachzoneshallincludeallfloorareathatis5morlessfromaglazedperim-
eterwall,exceptthatfloorareawithin5mofglazedperimeterwallshavingmore
thanoneorientationshallbedividedproportionatelybetweenzones.
Separatethermalzonesshallbeassumedforspaceshavingfloorsthatareincontactwiththe(c)
groundorexposedtoambientconditionsfromzonesthatdonotsharethesefeatures.
Separatethermalzonesshallbeassumedforspaceshavingexteriorceilingorroof(d)
assembliesfromzonesthatdonotsharethesefeatures.
HVAC
Systems
TheHVACsystemtypeandallrelatedperformanceparameters,suchasequipment
capacitiesandefficiencies,intheProposedDesignshallbedeterminedasfollows:
WhereacompleteHVACsystemexists,themodelshallreflecttheactualsystemtypeusing(a)
actualcomponentcapacitiesandefficiencies.
WhereanHVACsystemhasbeendesigned,theHVACmodelshallbeconsistent(b)
withdesigndocuments.Mechanicalequipmentefficienciesshallbeadjustedfrom
actualdesignconditionstothestandardratingconditionsspecifiedin§5,ifre-
quiredbythesimulationmodel.
Wherenoheatingsystemexistsornoheatingsystemhasbeenspecified,theheat-(c)
ingsystemshallbemodeledaselectricresistance.Thesystemcharacteristicsshall
beidenticaltothesystemmodeledintheStandardDesigns.
Wherenocoolingsystemexistsornocoolingsystemhasbeenspecified,thecoolingsystem(d)
shallbemodeledasanair-cooledsingle-zonesystem,oneunitperthermalzone.Thesystem
characteristicsshallbeidenticaltothesystemmodeledintheStandardDesigns.
TheHVACsystemtypeandrelatedperformanceparametersfortheStandardDesignsshall
bedeterminedfromTable10.2.Equipmentperformanceshallmeettherequirements
of§5.

ServiceHot
Water
Theservicehotwatersystemtypeandallrelatedperformanceparameters,suchas
equipmentcapacitiesandefficiencies,intheProposedDesignshallbedeterminedas
follows:
Whereacompleteservicehotwatersystemexists,the(a) ProposedDesignshallreflect
theactualsystemtypeusingactualcomponentcapacitiesandefficiencies.
Whereaservicehotwatersystemhasbeenspecified,theservicehotwatermodel(b)
shallbeconsistentwithdesigndocuments.
Wherenoservicehotwatersystemexistsorhasbeenspecifiedbutthebuilding(c)
willhaveservicehotwaterloads,aservicehotwatersystemshallbemodeledthat
matchesthesystemintheStandardDesignsandservesthesamehotwaterloads.
Forbuildingsthatwillhavenoservicehotwaterloads,noservicehotwatersystem(d)
shallbemodeled.
ThewaterheatingsystemshallbeofthesametypeoftheProposedDesign.Forresidential
facilities,hotelsandhospitalstheStandardDesignsshallhaveasolarsystemcapableof
meeting20%ofthedesignload.Systemsshallmeettheefficiencyrequirementsof§6.2.2,
thepipeinsulationrequirementsof§6.2.4andincorporateheattrapsinaccordancewith
§6.2.5.
Miscellaneous
Loads
Receptacleandprocessloads,suchasthoseforofficeandotherequipment,shallbe
estimatedbasedonthebuildingtypeorspacetypecategoryandshallbeassumedtobe
identicalintheproposedandStandardDesignss,exceptasspecificallyauthorizedbythe
AuthorityHavingJurisdiction.Theseloadsshallbeincludedinsimulationsofthebuilding
andshallbeincludedwhencalculatingthestandardbuildingperformanceandproposed
buildingperformance.
Receptacle,motorandprocessloadsshallbemodeledthesameastheProposedDesign.
Modeling
Limitationsto
theSimulation
Program
IfthesimulationprogramcannotmodelacomponentorsystemincludedintheProposed
Design,oneofthefollowingmethodsshallbeusedwiththeapprovaloftheAuthority
HavingJurisdiction:
Ignorethecomponentiftheenergyimpactonthetrade-offsbeingconsideredis(a)
notsignificant.
Modelthecomponentsubstitutingathermodynamicallysimilarcomponentmod-(b)
el.
ModeltheHVACsystemcomponentsorsystemsusingthe(c) StandardDesigns’sHVAC
systeminaccordancewith§5.
Whichevermethodisselected,thecomponentshallbemodeledidenticallyforboththe
ProposedDesignandStandardDesignsmodels.
Othersystems,suchasmotorscoveredby§8andmiscellaneousloadsshallbemodeled
asidenticaltothoseintheProposedDesignincludingschedulesofoperationandcontrol
oftheequipment.Wheretherearespecificefficiencyrequirementsin§8,thesesystems
orcomponentsshallbemodeledashavingthelowestefficiencyallowedbythose
requirements.Wherenoefficiencyrequirementsexist,powerandenergyratingorcapacity
oftheequipmentshallbeidenticalbetweentheStandardBuildingandtheProposed
Designwiththefollowingexception:variationsofthepowerrequirements,schedules,
orcontrolsequencesoftheequipmentmodeledintheStandardBuildingfromthose
intheProposedDesignmaybeallowedbytheratingauthoritybasedupondocumentation
thattheequipmentinstalledintheProposedDesignrepresentsasignificantverifiable
departurefromdocumentedconventionalpractice.Theburdenofthisdocumentation
istodemonstratethatacceptedconventionalpracticewouldresultinStandardBuilding
equipmentdifferentfromthatinstalledintheProposedDesign.Occupancyandoccupancy
schedulesmaynotbechanged.

Calculating Proposed and Standard Design10.3.1.1
Design Modela)
The Proposed Design and the corresponding Standard Design shall be consistent with information contained on the
plans and specifications. Some buildings, such as retail malls and speculative office buildings typically are built
in phases. For example, the core mechanical system may be installed with the base building, while the ductwork
and terminal units are installed later as part of tenant improvements.
For the purpose of calculating the Proposed Building, the rule is simple: the features that are not yet designed or
documented in the construction documents are assumed to minimally comply with the applicable prescriptive
requirements of the ECBC, as specified in Sections 4 through 8. In cases where the space use classification is
not known, the default assumption is to classify it as office space using the Building Area Method.
The WBP method is based on the assumption that non-residential buildings are both heated and cooled. Even
if not installed initially, it is common for buildings lacking a heating or cooling system to have one retrofitted
by future occupants. Accordingly, there is a special rule for calculating energy use in the Proposed Design when a
building’s HVAC system is heating-only or cooling-only: the building must be modeled as if it is going to have
both heating and cooling. The missing system is modeled as the default heating or cooling system that just meets
the prescriptive requirements of the ECBC. The same system is modeled for both Standard and Proposed Designs.
(Refer ECBC §4.0).
Space Use Classificationsb)
A key task in modeling the Proposed Design is assigning space use classifications to different areas of the building.
These classifications are used to assign lighting power density assumptions and to differentiate areas within the
building that may have different operating schedules and characteristics (thermostat settings, ventilation rates,
etc.). The choice of space use classifications is taken from one of the two lighting tables in the ECBC: either
Table 7.1 (Interior Lighting Power-Building area method) or Table 7.2 (Interior Lighting Power- Space Function
method). The designer may choose either classification scheme but may not mix the schemes by using one for
part of the building and the other for the rest of the building. “Building,” in this context, refers to the space
encompassed by a single building permit application, which may be less than the complete building.
The secondary support areas associated with each of the major building types would be included in each
building type. For example, if a building included both office and retail areas, the corridors and restrooms
associated with the office occupancy would be included in the office area and the storage or/and dressing room
areas associated with the sales floor would be included in the retail area.
Schedulesc)
Schedules are used to describe the percentage of a maximum design value of an internal load that is applicable
during a particular time period, usually one hour, i.e., lighting power density, miscellaneous equipment (plug
load) power density, occupant load or any other significant load thermostat set point (s) applicable in this
time period, or the availability (on/off), and control operation of a system or system component, e.g., cooling
systems, fans, chillers, or pumps.

Occupancy
Lighting
Equipment
Schedules have a large impact on the overall energy consumption. Designers are required to specify Weekday,
Saturday, Sunday, and Holiday operation in each schedule. An example for Weekday schedules in an office
building is shown below.
The ECBC allows designers to select reasonable or typical schedules for the building. In all cases, the schedules
for the Proposed Design and the Standard Design shall be identical. This means that the Proposed Design may not take
advantage of scheduling changes. It further means that any equipment in the Proposed Design that saves energy by
altering operating patterns or profiles must be modeled explicitly; it is not sufficient simply to assume a schedule
change and use that to account for the electricity savings.
An example is daylighting controls, which reduce lighting power when daylight is available in a space. The Proposed
Design must simulate the actual performance of the daylighting control in response to daylight availability, rather than
the simulator simply assuming some schedule change that arbitrarily reduces lighting power during daylight hours.
Another example of equipment that must not be modeled by reducing operating hours in the Proposed Design
are occupancy-sensing controls that turn off equipment when not needed. While this type of equipment might
well be installed because of the owner’s conviction that it is a good investment, there is no credit for it under
the WBP method.
In selecting the schedules, it is prudent to consider the likely long-term operation of the building. For example,
if a new school will initially operate on a traditional schedule, but the school district has a policy of shifting
its schools over to year-round operation, then it would be prudent to apply a year-round schedule in the WBP
method modeling.
The selected schedules should likewise not intentionally misrepresent the operation of the building. If a grocery
store chain keeps its stores open 24 hours a day, it would be inappropriate to use a 12-hour-a-day operating
schedule in the modeling.
Building Enveloped)
The building footprint and overall geometry must be identical for both the Standard and Proposed Designs, and
must use the design shown on the final architectural drawings, including building shape, dimensions, surface
orientations, opaque construction assemblies, glazing assemblies, etc. That is, they must have the identical
plan, conditioned floor area, number of floors, floor-to-floor distances, wall and roof areas, surface tilts and
orientation.
In some cases, the building envelope may already exist, as in the case of newly conditioned space or a tenant
build-out of a shell building; in these cases, the existing building envelope is modeled.
The Standard Design will have the maximum allowable window-to-wall-ratio (WWR) in each orientation, but

the Proposed Design may exceed this limit, provided compliance is achieved. Opaque assemblies like walls, roofs
and floors must be described by material layer as per the architectural drawings. For the Standard Design, the
characteristics (U-factor) of these envelope components are set to the prescriptive values specified in ECBC
§4.0.
The heat capacities for each assembly type must match the heat capacities of the Proposed Design. This is because
heat capacities may have a significant effect on the performance of envelope components, which shows up
in the simulation runs but they are not a requirement of the ECBC. Heat capacity is modeled to be the same
in both the Proposed Design and the Standard Design simulation runs, and so is energy neutral under the WBP
method.
For the Standard Design, exterior roof surfaces, other than those with ventilated attics, must be modeled assuming
a surface reflectance value of 0.30 (Refer ECBC Table 10.1). If a Proposed Design calls for a reflective roof
surface, however, the model may assume a long-term average reflectance of 0.45, which results in the lower heat
absorption of the reflective surface and makes a conservative allowance for degradation of the reflectivity over
its lifetime. For this exception to be allowed the specified reflectance of the roof in the Proposed Design must
exceed 0.70 and its emittance must exceed 0.75. (As per ASHRAE 90.1, 2004)
Windows /Fenestrationi)
The solar, thermal, and optical performance of windows systems are defined by the combination of four main
parameters, i.e., the area as defined by the window-to-wall ratio, thermal transmittance (U-factor), Solar Heat
Gain Coefficient (SHGC), and Visible Light Transmission (VLT).
Fenestration Area•
Fenestration areas and performance are strong drivers of energy use in buildings. Therefore, the ECBC places
great emphasis in how these values are calculated and applied for compliance.
ECBC §4.3.3 sets the prescriptive upper limits on vertical fenestration area and skylight area. If the fenestration areas
for the Proposed Design are less than these limits, the Standard Design shall have the same areas and orientations as the
Proposed Design.
If the fenestration areas in the Proposed Design exceed these limits, then the corresponding areas in the Standard
Design must be adjusted down to these limits AND corresponding increases made to opaque areas so that the
gross wall area and gross roof area are the same for both the Proposed Design and the Standard Design.
ECBC’s prescriptive envelope requirements do not provide an exception for street-level, street-side vertical
fenestration (e.g., store display windows). Thus, such fenestration must be modeled identically for the Proposed
Design and the Standard Design simulation runs so that the representation of these types of fenestration is energy
neutral.
U-Factors•
The U-factor for the Standard Design is set to the minimum required for the climate, as specified in ECBC Table
4.3. The minimum U-factor is a function of the percentage of glazing (WWR) in a wall or roof, as described
above.
Solar Heat Gain Coefficient•
The solar heat gain coefficient value for the fenestration applied in the Standard Design is set to the maximum
required for the climate and for each orientation, as specified in ECBC Table 4.3. The maximum SHGC is a
function of the glazing percentage of wall or roof, which is based on the Proposed Design as described above.
If the vertical fenestration to be used is unrated, then the SHGC values in ECBC Table 11.1 must be used.
Shading of Fenestrationii)
Glazing installed in the Standard Design must be modeled as being flush with its wall or roof surface, and without
any external shading devices. This ruling allows the Proposed Design to use to its advantage shading from window
recesses, overhangs, side fins, or other permanent shading devices that reduce solar gains on the glazing.

Interior shading devices, if not automatic, should not be modeled in the Proposed Design. In Standard Design, no
shading should be modeled.
Exceptions for Envelope
Any simulation program necessarily relies on a somewhat simplified description of the building envelope. It
is usually time-consuming and difficult to explicitly detail every minor variation in the envelope design, and
if good engineering judgment is applied, these simplifications won’t result in a significant decline in accuracy.
Three exceptions, where more substantial simplifications may be made, are:
Minor Assemblies: Frequently, there will be small areas on the building envelope with unique thermal
characteristics. The ECBC exempts any envelope assembly that covers less than 5% of the total area of a given
assembly type (e.g., exterior walls or roofs) from being treated as a separate envelope component. Instead, that
area may be added to an adjacent assembly of the same type. For example, if there is an exterior wall constructed
of load-bearing masonry, but there are small wood-framed infill areas, the infill areas may be treated as if the
entire wall is of masonry. Note that the gross wall area is unchanged, and no areas are left out of the model.
Different Tilt or Azimuth: This exception, primarily intended to address curved surfaces, specifies the minimum
number of orientations into which these surfaces must be split up. The Standard allows similarly oriented
surfaces to be grouped under a single tilt or azimuth, provided they are of similar construction and provided
the tilt or azimuth of the surfaces are within 45 degree of each other. They may be grouped as a single surface
or a multiplier may be used.
Fenestration: Interior and/or exterior shading devices in the Proposed Design shall not be modeled unless they
are automatically controlled. In the Standard Design, shades of any kind are not modeled. When the window
area in the Proposed Design exceeds the prescriptive maximum, the window area in the Standard Design is set to
the prescriptive maximum area and representative opaque wall area replaces any excess window area. Thus
the overall wall area (opaque wall + window area) is the same for both standard and proposed buildings. The
window area in Standard Design is decreased uniformly in each orientation so that the fraction of total window
area in each direction is the same in both Standard Design and Proposed Design simulation models.
Lighting Systemse)
Under the WBP method, lighting systems are a very important part of overall building performance for most
non-residential building types. Any lighting system efficiency improvements or reductions are reflected as energy
savings in the WBP method. The description of lighting systems in building energy simulation models must
incorporate the following two characteristics:
Application of a lighting power density (LPD) for each space or thermal zone of the building model.•
This may be determined using one of the two methods defined in §7.3.2 (building area method) or §7.3.3
(space function method).
An operational schedule for the lighting system which describes the percentage of the maximum LPD•
value that is energized during a particular hour
There are further requirements if the electric lighting system is to be controlled in response to the amount of
daylight in perimeter zones of the building. In such cases, the building simulation program must be able to
explicitly model daylight levels in each perimeter space that has daylight linking. Light sensors must be modeled
in these zones, and a control strategy must be applied that modulates electrical energy output from the electric
lighting system. Typically there are at least three daylight linked control schemes to modulate electrical energy
output:
Stepped control: in this control scheme, the electrical lighting system can respond to the presence of•
daylight in defined steps
Linear control: the lighting system modulates it’s output in a linear function to a prescribed minimum•
level, and

Linear/off: the lighting system modulates it’s output in a linear function and will switch off (use zero•
electrical energy) when there is sufficient daylight in the space
Either the building area or space function method may be used, but the categorization of spaces must be
identical between the Standard Design and the Proposed Design.
The LPD for the Proposed Design is taken from the design documents for the building. If a lighting system already
exists, then the lighting system design for Proposed Design will be based on the actual lighting power density of
the existing system. In the special case where no lighting system or design exists, as in a shell building where the
lighting will be installed by a future tenant, then a default lighting power density must be assumed, based on the
building area method for the appropriate building type. If no building type is known, then an office building is
assumed, (refer ECBC Table 10.1)
Exterior lighting systems as defined in ECBC §7.2.3 refers to grounds luminaires which operate at greater than
100W. They shall contain lamps having a minimum efficacy of 60 lm/W unless, the luminaire is controlled by a
motion sensor or exempt under §7.1, as mentioned below:
Emergency lighting that is automatically off during normal building operation and is powered by•
battery, generator, or other alternate power source
Lighting in dwelling units•
HVACf)
Incorporating HVAC systems into whole building energy simulation models is a complex process. It requires
knowledge of how buildings respond to climate, in addition to knowledge of the configuration of HVAC
systems and appropriate control strategies. For the purpose of building energy simulation it is useful to think of
the building model as having three HVAC type components, ZONES, SYSTEMS and PLANT.
HVAC Zoningi)
A key task in developing both of the simulation models is to divide the Proposed Design into a series of spaces or
“thermal zones” to be input to the energy simulation program. Due care and consideration needs to be taken
to divide the building into an appropriate number of thermal zones. There are several considerations for this
division, and some of these considerations can be conflicting. The following are some of the considerations
that need to be thought through when dividing the building for simulation analysis.
Building areas that are thermodynamically similar spaces and whose heating and cooling loads can be satisfied
through use of a single thermostat (or other type of temperature control) can be combined in a single thermal
zone. Since this requires mapping of the HVAC system design into the simulation model, the simulator needs
to work interactively with the services consultant.
Building areas that perform a similar function in the building design may be combined to form a thermal zone
– for example, some open plan office areas, or retail shop areas that have similar loads and operate similar
hours may be combined. These areas would have identical schedules applied for operation of internal loads and
HVAC systems.
Building areas that have the same lighting power density may be combined, i.e. the use of “space use
classifications.” The choice of space use classifications is taken from one of the two lighting tables in the ECBC,
either Table 7.1 (Interior Lighting Power-Building area method) or Table 7.2 (Interior Lighting Power-Space
Function method). The designer may choose either classification scheme but may not mix the schemes by using
one for part of the building and the other for the rest of the building.
“Building” in this context refers to the space encompassed by a single building permit application, which may
be less than the complete building. The secondary support areas associated with each of the major building
types would be included in each building type. For example, if a building included both office and retail areas,
the corridors and restrooms associated with the office occupancy would be included in the office area and the
storage or/and dressing room areas associated with the sales floor would be included in the retail area.
HVAC Zones are identical to the thermal zones or spaces discussed earlier. An HVAC designer will consider the

internal and external loads on each zone to calculate a “design day” cooling and heating load, and the maximum
outside air ventilation required. He or she may combine two or more thermal zones into a “thermal block”
designed to be conditioned by a single HVAC SYSTEM, for example, an Air Handling Unit (AHU) or an DX
system. If the building uses central air-conditioning systems (as opposed to DX systems, see Chapter 5), then a
series of HVAC SYSTEMS may be served by one or more HVAC PLANT component (chillers, pumps, cooling
towers etc).
For the WBP method using building energy simulation analysis, HVAC ZONES must be described to be
identical in both the Standard Design and the Proposed Design Models. This rule ensures consistency with the
requirement that the shape and area of the building envelope for the Standard Design be the same as for the
Proposed Design, and that the space use classifications be the same.
HVAC Zoning Based On HVAC Design
As noted earlier, building areas that are thermodynamically similar spaces and whose heating and cooling loads
can be satisfied through use of a single thermostat (or other type of temperature control) can be combined in a
single thermal zone. The outside air flow quantities, and control strategies applicable to the duct outlets or other
terminal units controlled by this single thermostats may be part of the HVAC ZONE description. Clearly, this
process requires mapping of the HVAC SYSTEM design into the simulation model, and the simulator needs to
work interactively with the services consultant.
Use of HVAC Zone Multiplier
In some simulation programs, the interior HVAC ZONES of a multi-story building, which may be physically
separate zones on each floor can be reasonably combined and treated as a single thermal zone with a multiplier.
Use of a multiplier allows simplification of the calculation of electricity consumption for the whole building
without having to repeatedly describe many similar or identical zones in the simulation model, thus saving time
and effort without significant loss of accuracy. However, a cafeteria or computer room in an office building
would need to be modeled separately, as would lower-floor retail uses.
The following conditions must be met to be able to use the multiplier option:
All of the space use classifications must be the same throughout the thermal zone. This ensures that•
they have the same load and schedule characteristics.
For exterior (or perimeter) HVAC ZONES with glazing, the glazing for all zones included in the•
thermal block must have the same orientation or at least their orientations must be within 45 degrees
of each other. This ensures that they have the same solar heat gain characteristics. This is not to say that
the zones may not have two or more glazing orientations – a corner office could easily have two – but
that the zones must have similar orientations. It would be acceptable, for example, to group all of the
northeast corner offices on the intermediate floors of an office tower into a single thermal block.
All of the HVAC ZONES in different floors must be served either by the same HVAC SYSTEM or•
by the same kind of HVAC SYSTEM. This is so that the simulation program can accurately model the
performance of the system (s) serving the zones.
HVAC Zoning When No HVAC Design Exists
In a situation where an HVAC ZONING plan has not been designed, then a configuration of thermal blocks
must be assumed for the WBP method. This situation is quite common in commercial buildings where the
future tenants will determine the zoning of spaces in the building. In this case, the building must be divided
into thermal zones based on similar internal load densities and lighting power densities, operational schedules,
occupancy patterns, space temperature schedules, etc. There are several guidelines that should be followed in
this situation, as described below.
Zoning Based on Perimeter and Interior Spaces
In situations when no HVAC design has been developed, divide the floor plate into perimeter spaces than are
within 5 meters of an exterior wall, and interior spaces that are more than 5 meters from an exterior wall.

Zoning Based on Glazing Orientation
Glazed exterior walls should be assigned to different perimeter thermal zones for each major orientation.
Orientations within 45 degrees of each other may be combined. Spaces with two or more glazed orientations,
such as corner offices, should be divided proportionately between zones having the different orientations.
Zoning Based on Floor Levels
Spaces exposed to ambient conditions, such as the top floor or an overhanging floor, and spaces in contact with
the ground, such as the ground floor, must be zoned separately from zones that are not exposed to ambient
conditions, such as intermediate floors in a multi-story building. Therefore, a multi-storey tower office building
could be divided into a top floor, a typical middle floor with the appropriate floor multiplier, and a bottom
floor.
Thermal Zones For Multi-Family Residential Buildings
Multifamily residential buildings are another special case. In general, the residential spaces must be treated
as separate thermal zones, except that some combinations are allowed. Units all facing the same orientation,
and having similar conditions at the top, bottom, and sides, may be combined. Similar corner units may be
combined, and units with similar roof or floor loads may be combined.
HVAC Systemsii)
Defining HVAC systems for use with whole building simulation programs is complex, and there are many inter-
related rules. Some of the rules that govern the description of HVAC SYSTEMS for the ECBC whole building
performance method are:
The HVAC SYSTEM described in the• Standard Design Model should just meet the prescriptive
requirements of the ECBC. These requirements are deemed representative of current standard practice
that meets the ECBC.
Where possible, the HVAC SYSTEM is to be conceptualized as completely as possible on the actual system•
designed for the Proposed Design. This includes the system type, equipment capacities and efficiencies,
controls, ancillary features (such as economizers), etc. The equipment efficiencies may need to be adjusted
to meet the needs of the simulation program. While efficiencies may be most accurately specified at the
building’s design conditions, most simulation programs require efficiencies to be specified at standard
rating conditions, such as those given in ECBC §5.0.
Where the entire HVAC SYSTEM design is not known, as in the case of a shell-and-core design, the•
unknown parts of the system are assumed to just meet the prescriptive requirements of the ECBC and
to be energy neutral. This strategy prevents gamesmanship with the undefined system components.
Gamesmanship is the practice of artificially reducing the efficiency of the Standard Design in order to
increase the apparent relative efficiency of the Proposed Design4.
Where the complete HVAC SYSTEM exists, the• Proposed Design and Standard Design are based on the
existing HVAC system – for example, fit out of an existing speculative building for a tenant. The subject
of the building permit is primarily the interior construction and lighting system and does not include the
HVAC system because it has already been built and permitted. Both simulation models would also include
the existing building envelope.
Where no HEATING SYSTEM exists, a default heating system must be assumed and modeled. It should•
be a simple heating system that burns fossil fuel, sized with sufficient capacity to meet the design heating
loads for the Proposed Design. An identical system (with sizing adjustments) must be assumed for the
Standard Design.
4 The WBP method is more vulnerable to this sort of abuse, which is why the rules for constructing the Standard Design must be so specific.
The WBP modeling rules for part-load efficiency and system sizing are intended to minimize these effects on the trade-off calculations for
the other measures in the building. For example, electricity consumption differences cannot be gained for a difference between a properly
sized HVAC system in the Proposed Design and an improperly sized HVAC system for the Standard Design. The modeling rules are discussed
individually in the following sections:

Where no COOLING SYSTEM exists, a default cooling system must be assumed and modeled for•
both the Standard Design and Proposed Design.
Minimum Efficiencies
The minimum efficiencies for HVAC equipment (§5.2.2) and for service hot water heating equipment (§6.2.2)
must be used for the applicable equipment in the Standard Design. This includes any part-load efficiencies, if
these are specified. These efficiency requirements set the baseline for equipment trade-offs under the WBP
method. The actual equipment efficiency of the Proposed Design is then used to calculate the Standard Design.
Since mechanical and service hot-water heating equipment efficiency is a prescriptive requirement, if the
equipment is covered by these equipment requirements, the equipment efficiency in the Proposed Design must
be equal to or greater than the prescriptive equipment efficiency. If mechanical or service hot water heating
equipment falls outside of those listed in the efficiency tables, the standard equipment efficiency shall be equal to
the efficiency of the equipment in the Proposed Design. Thus the only trade-off available for equipment efficiency
is to specify higher efficiencies than those called for in the ECBC, which would give electricity consumption
savings for the design.
Equipment Capacities
The equipment capacities for the Standard Design shall be based on sizing runs for each orientation (per Table
10.1) and shall be oversized by 15% for cooling and 25% for heating; i.e., the ratio between the capacities used
in the annual simulations and the capacities determined by the sizing runs shall be 1.15 for cooling and 1.25 for
heating. Unmet load hours for the Proposed Design or Standard Designs shall not exceed 300 (of the 8,760 hours
simulated), and unmet load hours for the Proposed Design shall not exceed the number of unmet load hours for the
Standard Design by more than 50. If unmet load hours in the Proposed Design exceed the unmet load hours in the
Standard Design by more than 50, simulated capacities in the Standard Design shall be decreased incrementally and the
building re-simulated until the unmet load hours are within 50 of the unmet load hours of the Proposed Design. If
unmet load hours for the Proposed Design or Standard Design exceed 300, then simulated capacities shall be increased
incrementally, and the building with unmet loads re-simulated until unmet load hours are reduced to 300 or less.
Sizing Runs
Weather conditions used in sizing runs to determine Standard equipment capacities may be based either on
hourly historical weather files containing typical peak conditions or on design days developed using 99.6%
heating design temperatures and 1% dry-bulb and 1% wet-bulb cooling design temperatures.
Preheat Coils
If the HVAC system in the Proposed Design has a preheat coil and a preheat coil can be modeled in the Standard system,
the Standard system shall be modeled with a preheat coil controlled in the same manner as the Proposed Design.
Fan System Operation
Supply and return fans shall operate continuously whenever spaces are occupied and shall be cycled to meet
heating and cooling loads during unoccupied hours. If the supply fan is modeled as cycling and fan energy is
included in the energy-efficiency rating of the equipment, fan energy shall not be modeled explicitly.
Ventilation
Minimum outdoor air ventilation rates shall be the same for the Proposed and Standard Designs.
Exception: When modeling demand-control ventilation in the Proposed Design when its use is not required by
Ventilation Controls for High-Occupancy Areas. Systems with design outdoor air capacities greater than 1400
L/s serving areas having an average design occupancy density exceeding 100 people per 100 m2 shall include
means to automatically reduce outdoor air intake below design rates when spaces are partially occupied.
Design Air Flow Rates
System design supply air flow rates for the Standard Design shall be based on a supply-air-to-room-air temperature
difference of 11°C. If return or relief fans are specified in the Proposed Design, the Standard Design shall also be

modeled with fans serving the same functions and sized for the Standard system supply fan air quantity less the
minimum outdoor air, or 90% of the supply fan air quantity, whichever is larger.
Supply Fan Power
System fan electrical power for supply, return, exhaust, and relief (excluding power to fan powered VAV boxes)
shall be calculated using the following formulas:
Pfan: 746 /(1 - e[ -0.2437839 × ln( bhp ) - 1.685541 ]) × bhp
Where Pfan: electric power to fan motor (watts)
bhp: brake horsepower of Standard fan motor from the table below, where cfm represents design
supply flow rate.
: Standard Fan Brake HorsepowerTable 10.2
Supply Air Volume Baseline Fan Motor Brake Horsepower
Constant Volume Systems 1 – 4 Variable Volume Systems 5 – 8
< 9400 L/s 17.25 + (cfm - 20000) × 0.0008625 24 + (cfm - 20000) × 0.0012
9400 L/s 17.25 + (cfm - 20000) × 0.000825 24 + (cfm - 20000) × 0.001125
Exception: If systems in the Proposed Design require air filtering systems with pressure drops in excess of 1 in. w.c. when
filters are clean, the allowable fan system power in the Standard Design system serving the same space may be increased using
the following pressure credit:
Pressure Credit (watts): CFMfilter * (Spfilter – 1)/4.984
where
CFMfilter: supply air volume of the proposed system with air filtration system in excess of 250 Pa
Spfilter: air pressure drop of the filtering system in w.g. when the filters are clean.
Exhaust Air Energy Recovery
Individual fan systems that have both a design supply air capacity of 2400 L/s or greater and have a minimum
outdoor air supply of 70% or greater of the design supply air quantity shall have an energy recovery system
with at least 50% recovery effectiveness. 50% energy recovery effectiveness shall mean a change in the enthalpy
of the outdoor air supply equal to 50% of the difference between the outdoor air and return air at design
conditions. Provision shall be made to bypass or control the heat-recovery system to permit air economizer
operation, where applicable.
Piping Losses
Piping losses shall not be modeled in either the proposed or Standard Designs for hot water, chilled water, or
steam piping.
Type and Number of Chillers
Electric chillers shall be used in the Standard Design regardless of the cooling energy source, e.g., direct fired
absorption, absorption from purchased steam, or purchased chilled water. The Standard Design’s chiller plant
shall be modeled with chillers having the number and type as indicated in table below as a function of building
conditioned floor area.
Table 10.3: Type and Number of Chillers
Building Peak Cooling Load Number and Type of Chiller (s)
≤300 tons 1 water-cooled centrifugal chiller
> 300 tons and < 600 tons 2 water-cooled centrifugal chillers sized equally
≥600 tons Minimum 2 water-cooler chillers with one or more chillers equal to
600 tons and one chiller less than 600 tons

Chilled Water Design Supply Temperature (System Type: RHFS /ECBC Table 10.2)
Chilled water design supply temperature shall be modeled at 6.7°C and return water temperature at 13°C.
Chilled Water Supply Temperature Reset (System Type: RHFS /ECBC Table 10.2)
Chilled water supply temperature shall be reset based on outdoor dry-bulb temperature using the following
schedule: 7°C at 27°C and above, 12°C at 16°C and below, and ramped linearly between 7°C and 12°C at
temperatures between 16°C and 27°C.
Chilled Water Pumps (System Type: RHFS from ECBC Table 10.2)
The Standard Design pump power shall be 349 kW/1000 L/s. Chilled water systems serving 11,148 m2 or more
shall be modeled as primary/secondary systems with variable-speed drives on the secondary pumping loop.
Chilled water pumps in systems serving less than 11,148 m2 shall be modeled as a primary/secondary system
with secondary pump riding the pump curve.
Heat Rejection (System Type: RHFS /ECBC Table 10.2)
The heat rejection device shall be an axial fan cooling tower with two speed fans. Condenser water design supply
temperature shall be 29°C or 5.6°C approach to design wet-bulb temperature, whichever is lower, with a design
temperature rise of 5.6°C. The tower shall be controlled to maintain a 21°C leaving water temperature where
weather permits, floating up to leaving water temperature at design conditions. The Standard Design condenser
water pump power shall be 310 kW/1000 L/s. Each chiller shall be modeled with separate condenser water and
chilled water pumps interlocked to operate with the associated chiller.
Supply Air Temperature Reset (System Type: RHFS /ECBC Table 10.2)
Supply air temperature shall be reset based on zone demand from the design temperature difference to a 5.6°C
temperature difference under minimum load conditions. Design air flow rates shall be sized for the reset supply
air temperature, i.e., a 5.6°C temperature difference.
VAV Minimum Flow Set points (System Type: ECBC Table 10.2)
Minimum volume set points for VAV reheat boxes shall be 2.15 L/s·m2 of floor area served.
Fan Power (System Type: RHFS /ECBC Table 10.2)
Fans in parallel VAV fan-powered boxes shall be sized for 50% of the peak design flow rate and shall be
modeled with 0.74 W per L/s fan power. Minimum volume set points for fan-powered boxes shall be equal to
30% of peak design flow rate or the rate required to meet the minimum outdoor air ventilation requirement,
whichever is larger. The supply air temperature setpoint shall be constant at the design condition.
VAV Fan Part-Load Performance (System Type: RHFS /ECBC Table 10.2)
VAV system supply fans shall have variable speed drives, and their part-load performance characteristics shall
be modeled using either Method 1 or Method 2 mentioned in table below.
: Part-Load Performance for VAV Fan SystemsTable 10.4
Method 1 – Part-Load Fan Power Data
Fan Part-Load Ratio Fraction of Full-Load Power
0.00 0.00
0.10 0.03
0.20 0.07
0.30 0.13
0.40 0.21
0.50 0.30
0.60 0.41
0.70 0.54

0.80 0.68
0.90 0.83
1.00 1.00
Method 2 – Part-Load Fan Power Equation
Pfan: 0.0013 + 0.1470 × PLRfan + 0.9506 × (PLRfan)2 -0.0998 × (PLRfan)3
where
Pfan: fraction of full-load fan power and
PLRfan: fan part-load ratio (current cfm/design cfm).
Hot Water Supply Temperature (System Type: ECBC Table 10.2)
Hot water design supply temperature shall be modeled as 82°C and design return temperature as 54°C.
Hot Water Supply Temperature Reset (System Type: ECBC Table 10.2)
Hot water supply temperature shall be reset based on outdoor dry-bulb temperature using the following
schedule: 82°C at –7°C and below, 66°C at 10°C and above, and ramped linearly between 82°C and 66°C at
temperatures between –7°C and 10°C.
Hot Water Pumps (System Type: ECBC Table 10.2)
The Standard Design hot water pump power shall be 301 kW/1000 L/s. The pumping system shall be modeled
as primary- only with continuous variable flow. Hot water systems serving 11,148 m2 or more shall be modeled
with variable speed drives, and systems serving less than 11,148 m2 shall be modeled as riding the pump
curve.
Service Hot-Water Systemsg)
Proposed Design
The WBP method provides an opportunity to include the service hot-water systems in the overall building
performance, and so for it to be part of the trade-off procedures. These systems are treated similarly to the
HVAC systems discussed above. The basic rule is that the Proposed Design hot water system is modeled in
accordance with the design documents, including equipment types, capacities, efficiencies, insulation, controls,
and all other related performance parameters. In cases where a service hot-water system already exists, the
model must be based on that system’s characteristics. If neither case applies, i.e. there is no service hot-water
system, then, none is modeled. The last rule is different than for other energy-related systems in the building
because service water heating generally has little interaction with the other energy systems. (Refer ECBC Table
10.1 (7))
Standard Designing
Service water-heating systems may participate in the WBP method trade-offs when they are eligible (under the
same permit application as the rest of the Proposed Design). They must be modeled as the same water heater
type and must be assumed to have the same performance characteristics, such as hot water demand, fuel type,
operating schedules, circulating pumps, etc. The only characteristic, then, that may contribute to electricity
consumption savings is the water heater equipment efficiency. There is a special case where the service water
heater is also used for space heating (or vice versa). For WBP method purposes, the Standard Design is assumed
to model solar system capable of meeting 20% of the design load for residential facilities, hotels and hospitals.
The equipment should be modeled so that system shall meet the efficiency requirements of ECBC §6.2.2, the
pipe insulation requirements of ECBC §6.2.4 and incorporate heat traps in accordance with ECBC §6.2.5.
Miscellaneous Loads:h)
Proposed Design
If there are significant energy-related systems, besides those discussed in above sections, that generate internal
heat gains or otherwise interact with the other energy systems, then they should be modeled as part of the

proposed and Standard Designs. For example, most nonresidential buildings have substantial plug loads and
some have process loads. These should be modeled using the best available information about their energy
characteristics from the design drawings or, when applicable, from the existing systems already in place. Systems
that do not interact substantially with other energy systems, such as elevators or parking garage fans, may be
neglected in the Proposed Building modeling. (Refer ECBC Table 10.1)
Standard Design
The WBP method does not Electricity consumption savings for non-HVAC motors or for other miscellaneous
energy-related equipment in a building, such as elevators, conveyors, autoclaves, etc. Where these systems
contribute significant loads to the building, they should be modeled, but they must be identical in the proposed
and standard runs. (Refer ECBC Table 10.1)
: HVAC Systems Map (Reproduced from ECBC 10.2)Table 10.5
Residential Nonresidential
More than 3 stories Less than 3
floors or less
than 7,500 m²
4 or 5 floors or less
than 7,500 m² or 5
floors or less and
7,500–15,000 m²
More than 5 floors
or more than
15,000 m²
Code PTACa PSZb RHFS RHFS
System type Packaged terminal air
conditioner
Packaged rooftop air
conditioner
Central cooling plant
with constant volume
AHU for each zone
Central cooling plant
with variable air volume
AHU for each zone
Fan control Constant volume Constant volume Constant volume air
handler for each zone
Variable air volume air
handler
Cooling type Direct expansion Direct expansion Chilled waterc Chilled waterc
Heating type Electric resistance Electric resistance Electric resistance Electric resistance
a PTAC equipment efficiency shall be per Table 10.6. A PTAC unit is a factory selected wall sleeve and separate un-encased combina-
tion of heating and cooling components, assemblies, or sections. It may include heating capability by hot water, steam, or electricity
and is intended for mounting through the wall to serve a single room or zone.
b PSZ equipment efficiency shall be per Bureau of Indian Standard 8148 (1988)
c If the proposed building has an air cooled chiller/system then the budget building shall have Air-cooled chiller otherwise the budget
case shall have water cooled centrifugal chillers. If the building has a mix of air and water cooled chillers then, the Standard Design shall
have the mix of air and water cooled chillers in the same proportion. Chiller Efficiencies shall be as per Table 5.1 of the Code.
: Electrically Operated Packaged Terminal Air ConditionersTable 10.6
Single-Package Vertical Air Conditioners – Minimum Efficiency Requirements
Equipment Type Size Category
(Input)
Subcategory or
Rating Condition
Minimum Efficiency
PTAC (Cooling Mode) New Con-
struction
All capacities 35°C db outdoor air 3.66 – (0.213 × Cap/1000)b COP
PTAC (Cooling Mode) Replace-
mentsa
All capacities 35°C db outdoor air 3.19 – (0.213 × Cap/1000)b COP
a Replacement units must be factory labeled as follows: “Manufactured for Replacement Applications Only; not to be Installed in New Construction
Projects.” Replacement efficiencies apply only to units with existing sleeves less than 16 in. high and less than 42 in. wide.
b Cap means the rated cooling capacity of the product in Btu/h. If the unit’s capacity is less than 7000 Btu/h, use 7000 Btu/h in the
calculation. If the unit’s capacity is greater than 15,000 Btu/h, use 15,000 Btu/h in the calculation.
Source: ASHRAE 90.1, 2004
Percentage Improvement
The formula below demonstrates a percentage performance improvement in the proposed and Standard Design

per ECBC by a whole building performance using building performance rating method used in chapter 10 of
ECBC. The minimum energy saving percentage applicable to LEED-India and GRIHA rating systems is, as
under.
%Improvement=100×(EnergyUseinStandardDesign -EnergyUseinProposedDesign)/EnergyUsein
ProposedDesign

Case Study
To demonstrate ECBC compliance for building design using WBP method, building energy simulation models
need to be developed. This document uses two important terms to understand the process – Standard Design
and the Proposed Design. To evaluate energy performance of the Proposed Design and to see if it is compliant with
ECBC, one needs to build a hypothetical simulation model based on the methodology described in Appendix
B of the Guide (also explained in this Guide). This hypothetical model is called Standard Design. Sometimes
Standard Design is also referred to as “Base Case”. Energy consumption in the Standard Design is compared
with the energy consumption in the Proposed Design. If the energy consumption in the Proposed Design is more
than that of the Standard Design, one needs to incorporate energy conservation measures (ECMs) to improve
the energy performance of the Proposed Design for achieving ECBC compliance. Hence in this case study after
analyzing the design inputs and incorporating the ECMs, the Proposed Design model has been created. The
process of creating the Standard Design model and the Proposed Design model, their inputs for simulations and
their results are discussed and explained in this case study. The hypothetical building used in the case study is
located in Ahmedabad, Gujarat, India.
The steps involved for ECBC compliance using WBP method are:
Ensure that the building design conforms to the local building bye laws and regulations1.
Comply with the mandatory requirements of the ECBC2.
Create the3. Proposed Design model
Create the4. Standard Design model
Compare the energy consumption of the5. Proposed Design with that of the Standard Design
If the energy consumption of the6. Proposed Design is more than that of Standard Design, incorporate
additional ECMs in the Proposed Design
Ensure that the7. Standard Design created in Step 4 is still valid. If necessary, revise the Standard Design
Repeat step 5 through 7 till energy consumption in the8. Proposed Design is less than or equal to the energy
consumption in Standard Design
Prepare the compliance documents9.
All the above steps are dealt with in detail in this chapter.
Before commencing with the data input process for the model, the project should refer to Appendix E -
Climate Zone Map of India in the Code to check the climate zone in which the site is located. The Guide also
lists various cities and their corresponding climate zones. Weather files for 58 cities from India are available at:
http://www.eere.energy.gov/buildings/energyplus/cfm/weather_data3.cfm/region=2_asia_wmo_region_2/
country=IND/cname=India. This weather data is ready to be used in EnergyPlus simulation software but
can be customized for other simulation tools using appropriate weather file converter program. The building
proposed for the case study is in Ahmedabad, which is classified under hot and dry climate.
The building should then be classified either as a 24-hour activity building or a daytime activity building because
the ECBC specifications for the U-factors of the building envelope are mandated according to the climate zone
and the occupancy type of the building.
However, before going into the details of ECBC compliance, it is necessary to describe the case study used for
demonstration.
Building Description
The building proposed for the case study is in Ahmedabad, which is classified under hot and dry climatea.

as per Appendix E of the Code.
The building in this case study is a daytime use building.b.
The building used in this case study is a square building with one side measuring 39.62 m. The buildingc.
has ten floors with identical plan. The entire building is conditioned space with a total conditioned area
of 15,717 sq m (all ten floors). The building is exposed on all the four sides. Windows on all four sides
together constitute a WWR of 45%. There are permanent external shading devices designed for the
proposed building.
The HVAC design and consequently zoning for the proposed building have not been finalized henced.
according to Table 10.1 for each floor a simple core-perimeter zoning pattern, as shown in the Figure
10.1, has to be considered. The depth of perimeter zones is 5m as per guidance provided in this
chapter. All the five zones are considered to be conditioned office areas.
: Five zone floor plate showing the perimeter and core zoningFigure 10.1
Construction consists of typical reinforced cement concrete (RCC) column and beam structure withe.
flat slab. External wall is made of brick with cement plaster. 45% of all façade area comprises of glazing
that is flush with the external wall. Internal partition walls are designed as brick construction with
cement plaster on both sides. No insulation is used in the roof and walls.
Water-cooled centrifugal chillers are proposed to meet the cooling requirements of the building. All thef.
spaces in the building will be served with variable air volume (VAV) air handlers. The system consists
of chilled water circulation with evaporator, condenser and a chilled water circulation pump. Two
chillers, each of 262 tons and with COP of 5.55 are proposed to meet the cooling requirements of the
building.
The fenestration consists of a double-glass unit in aluminum frame with the following properties:
: Fenestration SummaryTable 10.7
Façade WWR SHGC
North 62% 0.36
South 25% 0.36
East 35% 0.23
West 55% 0.36
The building design includes the following features, which incorporate some passive design methods to reduce
energy consumption of the building in hot and dry climate (Ahmedabad) and still strive for a high WWR on
certain facades to take advantage of daylight:
The WWR on the northern façade is 65%. In a city like Ahmedabad, which is 23º N latitude, the sun•
rarely goes to the north of the building, hence there will be almost no direct light coming into the
building from the North. North glazing brings in diffused light, which is preferred for office activity.

The building has a WWR of 25% on the East side and a WWR of 55% on the West side.•
Ahmedabad being in a hot climate, the solar heat gain coefficient of the glass plays an important role.•
In this regard, the windows on East façade (where horizontal and vertical shading devices would not
be very effective) of the building are proposed with a double glazed unit of low SHGC value of 0.23.
Windows on the South, North and West facades have a double glazed unit with SHGC of 0.36.
On the south façade of the building, overhangs of 0.6 m depth have been designed to reduce the direct•
light coming inside the building.
To reduce high solar heat gain from the West side, vertical louvers/fins of 0.6 m width at a gap of 1.5•
m are proposed.
To take advantage of the high visible transmittance (0.62) of double glazed unit and high WWR in the•
North and the West facades, perimeter zones in these directions are equipped with daylight sensors that
can dim the internal lighting in these zones.
Steps for ECBC Compliance
Ensure that the building design conforms to the local building bye laws and regulationsStep 1:
It is recommended to ensure that the building design conforms to the local building bye laws and regulations.
The design team should request clear guidance from the local authorities on the following issues:
Applicability of ECBC to the project•
Submittal requirements and procedure to apply for ECBC compliance•
Any local amendments to the ECBC that need to be followed•
Acceptability of the weather file to the authorities•
Comply with the mandatory requirements of the ECBCStep 2:
All the mandatory requirements of the ECBC code must be met by the project. The mandatory provisions of
building envelope, HVAC, service hot water and pumping, lighting and electrical power are provided in sections
4.2, 5.2, 6.2, 7.2 and 8.2 respectively of the Code and must be complied with. It should be noted that even if the
WBP method is adopted for ECBC compliance, mandatory requirements must still be followed even though
one might not follow any or all of the prescriptive requirements.
Create the Proposed Design Simulation ModelStep 3:
The simulation model should be developed as per the Proposed Design guidelines provided in Table 10.1 of the
Guide. This table is an updated version of Table 10.1 of ECBC and provides detailed guidance to the users in
creating both the Proposed and Standard Design.
This section describes the methodology for creating the Proposed Design simulation model. All the assumptions
while creating the model must be stated clearly and unambiguously and the simulation model of the Proposed
Design should be prepared using approved simulation software. The simulation software must meet all the
specifications listed in Section 10.2.1 of Appendix B of the Code.
Building Envelope
While modeling, the following should be noted:
Walls within 45 degrees of each other can be combined into a single wall and assumed to have one•
orientation.
The building in the• Proposed Design case is to be modeled only for the actual designed orientation.
All the building envelope materials in the simulation model shall be as per the• Proposed Design of the

building. Thermal specifications of walls must include thermal mass (specific heat and density) as well
as thermal resistance (U-factor or R-value).
In this case study, the external wall section in the• Proposed Design is a 230 mm brick wall with cement
plaster on either side. If the manufacturer provides the material properties, they should, after verification,
be used to calculate the final U-factor of the construction assembly. However, in this case study it is
assumed that no data was available from the manufacturer. Thermo-physical properties of construction
materials can be obtained from two sources:
Appendix C of ECBC––
Libraries included in the simulation program––
For this case study, the properties of the specified materials were derived from the simulation software•
library, which were assembled to form the building envelope. The resultant U-factor of the wall works
out to be 2.02 W/m2·K. Similarly, U-factor of the roof, which is an un-insulated RCC slab, works out
to be 1.618 W/m2·K.
While modeling the facades of the building, the windows need to be modeled separately if the building•
uses daylight controls. Otherwise they can be combined (if they are in the same zone) into a larger
effective window. Manually operated window-shading devices such as blinds or shades should not be
modeled. However, any permanent shading devices such as fins, overhangs, and light-shelves have to
be modeled as they have significant impact on the overall heat gain as well as daylight in the building.
Since, India presently does not have a labeling program certifying the U-factor of the windows, the
project’s Proposed Design needs to comply with the requirement of the ECBC (for unrated vertical
fenestration) as specified in Table 11.1 of Appendix C. As per this table, the U-factor of the window
assembly of the case study model is 5.1 W/m2·K. Manufacturer has however provided the SHGC (0.36
and 0.23 for two types of glazing used in the building) and Visible Light Transmittance values (0.62 and
0.41 for two types of glazing).
For exterior roofs other than roofs with ventilated attics, the reflectance and emittance of the proposed•
roof surface, which can be derived from building material specifications, should also be modeled. For
the case study, the roof surface has been modeled with a reflectance of 0.45 since the reflectance and
emittance of the roof surface is exceeding the Code requirements as specified in Table 10.1 (Building
Envelope) of the Guide.
Schedules
Office schedule with varying occupancy from 7 am to 12 mid-night has been proposed for the building. Normal
office schedule will be from 9 am to 6pm.
Lighting
For the Proposed Design:
The design electric lighting power should be modeled accurately for the purpose of simulation.•
The lighting system power should include all lighting system components shown or provided for in the•
plans (including lamps, ballasts, task fixtures, and furniture-mounted fixtures).
In cases where the electrical design includes lighting controls, they should be included in the simulation•
model.
For the case study:
An LPD value of 8.61 W/m2·has been used in the office areas.•
Daylight sensors are proposed in the design of the lighting systems on the North and West facades.•

HVAC Zoning
Where a complete HVAC system has been designed, the simulation model should be consistent with the design
documents. It should reflect the actual zoning scheme.
For the case study:
Since the HVAC zoning has not been designed/finalized, the ECBC User Guide mandates that a simple•
perimeter and core zoning should be done.
The perimeter areas are modeled with a depth of 5 meters from exterior wall for four cardinal directions•
along with a central core area.
: Simplified Zoning of the Case Study Building when HVAC Zoning is Not DesignedFigure 10.2
HVAC Systems
For the Proposed Design:
The HVAC system should be specified according to the mechanical layout of the design. All the inputs•
should be as per the designs, which include the fan and equipment efficiencies, static pressure, pump
heads, etc. None of the default values by the software should be considered as input values for the
above parameters unless they match the actual proposed values.
When the HVAC system is designed, the system type and all actual component capacities and efficiencies•
should be modeled as per the actual system design. Any HVAC specific energy-efficiency features, for
example, economizers, variable-air-volume drives etc., should also be included in the simulation model
as per the specifications in the design documents.
For the case study,
The building is served by VAV air-handling units, which are connected to the centrifugal chillers. Water-•
cooled centrifugal chillers are proposed to meet the cooling requirements of the building.
The system consists of chilled water circulation with evaporator, condenser and a chilled water•
circulation pump. Two chillers, each of 262 tons and with COP of 5.55 are proposed to meet the
cooling requirements of the building. All the power and efficiencies of the system fan match with
the Standard Design specifications. No savings is taken in the HVAC system design except the variable
speed fan used in the water-cooled condenser in place of the two-speed fan in the Standard Design as the
complete HVAC system is not designed in the case study.

Miscellaneous Loads
For the case study, an internal equipment load of 21.6 W/m2 has been considered for both the Proposed Design.
Create the Standard Design simulation modelStep 4:
The simulation model should be developed as per the Standard Design guidelines provided in Table 10.1 of the
Guide. The Standard Design model is created using the Whole Building Performance method specified in ECBC.
Once the model has been created, the simulation runs will show the energy consumption of the Standard
Design building.
The Standard Design is created with building specifications that comply with all prescriptive requirements of the
ECBC. In the simulation model of the Standard Design, the glazing area is equally distributed on all sides of the
building.
For the Standard Design, the energy use shall be generated by simulating the building with its actual orientation
and subsequently rotating the building by 90, 180 and 270 degrees. The energy use for the Standard Design will
be obtained by taking an average of energy use from the simulation runs for four different orientations.
Site and Climate
All the input parameters in the Standard Design will be same as in the Proposed Design model.
Building Envelope
While modeling, the following should be noted:
Walls: The proposed building has two types of walls: external walls and internal partitions. Walls of the building
should be categorized based on their position within the building. Appendix A of the Code, deals with the
definitions of various kinds of walls in a building. The wall construction must comply with the prescriptive
requirements of Section 4.3.2 of the Code. For the case study, since the building is in hot and dry climate and is
a daytime use building, according to Table 4.3.2 of the Code, the U-factor of the wall shall be 0.44 W/m2·K.
Roof: The roof construction must comply with the prescriptive requirements of Section 4.3.1 and 4.3.2 of the
Code. For the case study, a mass construction roof with a U-factor of 0.409 W/m2.K has been specified in the
Standard Design model. Table 10.1 provides guidance on how to model the reflectivity of the roof.
Windows:
In the Standard Design:
Windows in all the directions have the same prescriptive requirements for SHGC and the U-factor.•
Windows should be equally distributed on all the sides.•
U-factor and the SHGC requirements depend on the window wall ratio (WWR) and the climate zone.•
The U-factor, SHGC and Visible Light Transmittance of the glass must meet the requirements set forth•
in Section 4.3.3 of the Code.
Shading should not be modeled, whether internal or external. Self-shading of the building too shouldn’t•
be modeled as per Table 10.1 (Building Envelope).
For the case study:
Since the• Proposed Design has a WWR of 45%, as per Table 10.1 (Building Envelope) of the Guide, the
WWR in the Standard Design shall be limited to 40%.
All the windows in the• Standard Design shall have a U-factor of 3.3 W/m2.K and SHGC of 0.25 as per
Table 4.3 of the Code.

Space Use
According to Appendix A of ECBC, the floor area of a building is categorized as ‘conditioned-space’, ‘semi-
heated /cooled space’ or ‘un-conditioned’ space. ECBC defines ’conditioned space’ as a cooled space, heated
space, or directly conditioned space in the building. A ‘semi-heated space’ is defined as an enclosed space within
a building that is heated by a heating system whose output capacity is greater than or equal to 10.7 W/m2 of
floor area but is not a conditioned space. An ‘un-conditioned space’ is one that is not a conditioned space or
a semi-heated space. Crawl spaces, attics, and parking garages with natural or mechanical ventilation are not
considered as enclosed spaces.
For the case study, the entire floor plate is assumed to be conditioned space.
Lighting
For the Standard Design:
The lighting power density (LPD) should be specified using either the Building Area method or the•
Space Function method. In Building Area method (Table 7.1 of ECBC) an average LPD value is
defined for the entire building, whereas, in Space Function method (Table 7.2 of ECBC), individual
spaces are assigned with different LPD values based on the activity within that space.
For the case study:
The Building Area method has been followed in the case study. A LPD of 10.8 W/m• 2 is considered in
all the office areas as per Table 7.1 of ECBC, assuming all the areas to be office.
HVAC Zoning
This zoning pattern is the same for both Proposed Design and the Standard Design model.
HVAC Systems
As specified in Table 10.2 of Appendix B of the Code, the HVAC system of the Standard Design model is based
on:
The building type: residential or non-residential•
The total built-up area excluding the parking area of the building•
For the case study:
Based on the above two categories, the heating system of the• Standard Design model is served by the
Reheat Fan System (RHFS)
Since the• Proposed Design has a water cooled chiller, the Standard Design will also have water cooled
centrifugal chiller as specified in the footnote of Table 10.2 of Appendix B of the Code.
In the• Proposed Design there is no heating system provided for the building. However, since the Standard
Design should also be modeled with heating, the same kind of provision is assumed for the Proposed
Design simulation model as well.
The• Standard Design, consists of a centrifugal chiller which is water cooled with a variable air volume
(VAV) AHU for each zone.
The cooling type is chilled water and the heating is provided by electric resistance.•
Fans and controls: As specified in the mandatory provisions given in Section 5.2.3 of the Code, all the
mechanical cooling and heating systems should be controlled by respective schedules and set-point temperatures.
The supply fans should be controlled by variable speed drives as specified in Section 5.3.2.

Number of Chillers and Sizing:
The size of the chiller, which decides the COP of the chiller as per Table 5.1 of the Code is given in•
accordance with the following table.
To decide the size of the chiller, a sizing run for the• Standard Design is performed. The sizing ratios
for this model would be 15% oversized for the cooling and 25% oversized for the heating unit as
mentioned in the Code. .
In cases, where HVAC efficiency values are not specified in the Code, they should be referred to•
Appendix Go of ASHRAE 90.1-2004. If values are specified neither in ECBC nor in ASHRAE 90.1-
2004, they should be taken from the Proposed Design.
For the case study:
• Table 10.3 of the Guide has been followed for determining the number of the chillers and their sizes
in the case study building.
The system consists of chilled water circulation with evaporator, condenser and a chilled water•
circulation pump. Two chillers, each of 232 tons and with COP of 5.55 are proposed to meet the
cooling requirements of the building
Service Hot Water
When there is service hot water supply for the Proposed Design, similar system must be modeled in the Standard
Design model. In this case study, since the Proposed Design is not a residential, hotel or hospital building, 20% of
design loads are not required to be met by solar hot water system. The system efficiencies shall be as per Section
6.2.2 of the Code.
Miscellaneous Loads
The equipment loads in the Standard and the Proposed Design shall be modeled in the same way.
Compare the Energy consumption in the Proposed Design with that of Standard DesignStep 5:
A review of the detailed inputs of both the Standard Design model and the Proposed Design model shows that the
building does not meet the U-factor requirements for the wall as specified in the prescriptive table of ECBC.
Since the fenestration is unlabeled, the resultant U-factor of the complete window assembly is also high when
compared with the U-factor of the Standard Design simulation model. However the internal lighting load is 20%
less in the Standard Design model. A glass of higher SHGC has been used on the West, South and North side of
the building and a glass of SHGC lesser than the base case has been used on the East facade. The windows are
designed in such a way that mainly diffused light get into the building from the North façade. West façade has a
high WWR of 55% but because there is good shading provided in the form of vertical fins, the effect of high
WWR has been compensated to a certain extent. Also, as the building is a daytime office use building, the effect
of West sun would be mainly in the unoccupied hours.
Both the Proposed Design Model and the Standard Design models are simulated and the results are analyzed to
check for errors, if any. In some cases, there are instances when either the cooling set-point or the heating
set-point temperatures are not met by the HVAC system or the plant. They are normally categorized as either
system unmet or plant unmet hours, which state the number of hours the system or the plant was unable to
meet the cooling or heating load. The maximum allowable unmet hours either for the Proposed Design or the
for the Standard Design are 300 hours as per Appendix B of the Code and if the number of hours that loads
are unmet by either the system or plant shows a difference of more than 50 hours between the Standard and
Proposed Design models, the simulation results are not accepted as valid. The best way to deal with this issue is to
confirm that the sizing method of both the Standard and Proposed Design is similar. It could also be the case that
some part of the HVAC system is undersized and may require redesign. These models are refined and re-run
and checked for all the compliance clauses again and if found in order, prepared for compliance documentation

checks.
Some key differences in modeling the Standard Design and the Proposed Design model are as follows:
The• Standard Design may differ from the Proposed Design model in the specification of building envelope
U-factors, glazing SHGC, lighting power density and mechanical efficiency of HVAC system.
The other major difference is in the modeling of the glazing. In the• Standard Design the glazing WWR
is spread on all the façades equally, as specified in the Building Envelope of Table 10.1 of Appendix
B. Moreover, there is no self-shading of the building allowed as specified in Table 10.1. No assumed
efficiency measures should be modeled over the Proposed Design to meet or to perform better than
Standard Design. However efficiency options, which are designed for implementation in the proposed
building can be included in the Proposed Design simulation model.
Not neededStep 6:
Not neededStep 7:
Not neededStep 8:
Prepare the compliance documentsStep 9:
For the project to finally comply with the Code, the required compliance documents should be prepared and
filed as submittals to show that the Proposed Design consumes energy less than or equal to the Standard Design
model. Table 10.8 provides Whole Building Performance compliance report making it easier for users to show
compliance.
: Building Energy Model InformationTable 10.8
Whole Building Performance Method Compliance Report
Project Name IT Park
Project Address Date: June 2009
Designer of Record: Telephone:
Contact person: Telephone:
City: Ahmedabad
Weather Data: Ahmedabad - IWEC weather data
Climate Zone: Hot and dry
Total Conditioned Area (sq ft) Total Unconditioned Area (sq ft) Total Floor Area (sq ft)
15,717 sqm 0 sqm 15,717 sqm
Advisory messages
Proposed Design Standard Design Difference
Number of hours of heating loads unmet (system/plant) 0 hours 0 hours 0 hours
Number of hours of cooling loads unmet (system/plant) 52 hours 44 hours 8 hours
Number of warnings 12 12 0
Number of errors 0 0 0
Number of defaults overridden
Additional Building Information
Number of floors G+9
Simulation program Visual DOE 4.1.2 based on DOE 2.1 E
Comparison of Input Parameters in Proposed Design and Standard Design

Building Element Proposed Design Input Standard Design Input
Envelope
Above Grade Wall Construction(s) U value 2.02 W/m2.K ( 230 mm thick
wall + Cement motar either side)
U value 0.44 W/m2.K ( 230 mm thick
wall + Insulation) (outside to inside)
Below Grade Wall Construction - -
Roof Construction U value 1.618 W/m2.K (150 mm RCC
slab+ Cement motar either side)
U value 0.409 W/m2.K (Insulation
+150 mm RCC slab) (outside to
inside)
Exterior Floor Construction NA NA
Slab-on-Grade Construction NA NA
Window-to-Gross Wall Ratio 40% 45%
Fenestration Type(s) U factor=5.1 W/m2.K U factor =3.3 W/m2.K
Fenestration Assembly U Factor SHGC1 = 0.23, SHGC2= 0.36 SHGC = 0.25
Fenestration Assembly SHGC VLT1 = 0.41, VLT2= 0.62 NA
Fenestration Visual Light Transmittance 0.6 m fixed overhangs on South & 0.6
m wide vertical fins on West side
None
Fixed Shading Devices None None
Automated Movable Shading Devices
Electrical System & Process Loads
Ambient lighting power density and Lighting
Design Description.
8.61 W/m2 10. 8 W/m2
Process Lighting
Lighting occupant Sensor Controls None None
Day lighting Controls In North and West perimeter zones None
Receptacle Equipment 21.6 W/m2 21.6 W/m2
Elevators or Escalators - -
Refrigeration Equipment - -
Other Process loads - -
Mechanical & Plumbing Systems
HVAC System Type (s) Variable Air Volume Constant Air Volume
Design Supply Air Temperature Differential
Fan Control VSD control VSD control
Fan Power 0.0012 bhp/cfm 0.0012 bhp/cfm
Economizer Control None None
Demand Control Ventilation None None
Unitary Equipment Cooling Efficiency NA NA
Unitary Equipment Heating Efficiency NA NA
Chiller Type, Capacity, And Efficiency 2 x 262 tons Water cooled centrifugal
chiller COP 5.55
2 x 232 tons Water cooled centrifugal
chiller COP 5.55
Cooling Tower One two cell, with VSD control One two cell, with two speed control
Boiler Efficiency - -
Chilled Water loop and Pump Parameters Pump head = 9.2 m; Efficiency = 0.9 Pump head = 9.2 m; Efficiency = 0.9
Condenser Water loop and Pump Parameters Pump head = 4.5 m;
Impeller efficiency 0.77
Motor efficiency = 0.9
Flow 3 gpm/ton
Pump head = 4.5 m;
Impeller efficiency 0.77
Motor efficiency = 0.9
Flow 3 gpm/ton
Hot Water Loop and Pump Parameters - -
Domestic Hot Water pump Parameters - -

Standard Design - End Use Summary
End use 0 rotation 90 rotation 180 rotation 270 rotation Average
Energy
Type
Energy
(kWh)
Peak
(kW)
Energy
(kWh)
Peak
(kW)
Energy
(kWh)
Peak
(kW)
Energy
(kWh)
Peak
(kW)
Energy
(kWh)
Peak
(kW)
Interiors
Lighting
Elec 492,303 152.1 492303 152.1 492303 152.1 492303 152.1 492,303 152.1
Interior lighting
(Process)
Elec - - -- - - - - - - -
Exterior
Lighting
Elec
Space heating
(Fuel 1)
Natural
Gas
- - - - - - - - - -
Space heating
(Fuel 2)
Elec 3,065 110.1 3,252 108.4 3,389 109.7 3,164 108.8 3,218 109.25
Space Cooling Elec 817,716 338.1 815,756 338.1 815,690 338.1 816,411 338.1 816,393 338.1
Pumps Elec 10,922 4.5 10,894 4.5 10,893 4.5 10,903 4.5 10,903 4.5
Heat Rejection Elec 44,840 16.2 44,766 16.2 44,768 16.2 44,776 16.2 447,88 16.2
Fans Interior Elec 261,403 163.2 260,962 163.2 260,769 163.1 261,215 163.2 261,087 163.175
Fans Parking
garage
Elec - - - - - - - - - -
Service Water
Heating (Fuel
1)
Natural
Gas
- - - - - - - - - -
Service Water
Heating (Fuel
2)
Elec 11,324 4.4 11,324 4.4 11,324 4.4 11,324 4.4 11,324 4.4
Receptacle
Equipment
Elec 984,607 304.2 984,607 304.2 984,607 304.2 984,607 304.2 984,607 304.2
Refrigeration
(Food, etc.,)
Elec - - - - - - - - - -
Cooking
(commercial,
fuel 1)
Elec - - - - - - - - - -
Cooking
(commercial,
fuel 2)
Elec - - - - - - - - - -
Elevators and
Escalators
Elec - - - - - - - - - -
Other Process Elec - - - - - - - - - -
Total Building
Consumption/
Demand
Elec 2626180 1092.8 2623864 1091.1 2623743 1092.3 2624703 1091.5 2624623 1091.925
Total Process
Energy
Elec 984607 304.2 984607 304.2 984607 304.2 984607 304.2 984607 304.2
Energy Summary by End Use
Proposed Design Standard Design
End Use Energy Type Energy
(kWh)
Peak
(kW)
Energy
(kWh)
Peak
(kW)
Energy
(%)
Interior Lighting (Ambient) Electricity 328,049 97.9 492,303 152.1 33.36%
Interior lighting (Process) Electricity
Exterior Lighting Electricity
Space Heating (fuel 1) Natural gas

Space Heating (fuel 2) Electricity 3,527 97.9 3,218 109.25
Space Cooling Electricity 896,924 381.9 816,393 338.1 -9.86%
Pumps Electricity 11,954 5.1 10,903 4.5 -9.64%
Heat Rejection Electricity 48,025 18.3 44,788 16.2 -7.23%
Fans - Interior Electricity 299,416 150.3 261,087 163.17 -14.68%
Fans-Parking Garage Electricity - - - -
Service Water Heating (fuel 1) Natural Gas - - - - -
Service Water Heating (fuel 2) Electricity 11,324 4.4 11324 4.4 0%
Receptacle Equipment Electricity 984,607 304.2 984,607 304.2 0%
Refrigeration (food, etc.,) Electricity - - - - -
Cooking (commercial, fuel 1) Natural Gas - - - - -
Cooking (commercial, fuel 2) Electricity - - - - -
Elevators and Escalators Electricity - - - - -
Other Process Electricity - - - - -
Total Building Consumption 2583,826 1060 2624,623 1091.9 1.55%
Proposed Design Standard
Design
Percentage
Improvement
Type Energy Use
(kWh)
Energy Use
(kWh)
Energy Use
(%)
Nonrenewable (Regulated & Unregulated)
Electricity 2583,826 2624,623 1.55%
Natural Gas - - -
Steam or Hot water - - -
Chilled Water - - -
Other - - -
Total Nonrenewable Regulated & Unregulated) 2583,826 2624,623 1.55%

Appendix C: Default Values For Typical Constructions
Energy Conservation Building Code (ECBC) User Guide C.1
APPENDIX C: Default Values for Typical
Constructions
Procedure for Determining Fenestration Product U-Factor11.1
and Solar Heat Gain Coefficient
§4.2.1.1 and §4.2.1.2 require that U-factors and solar heat gain coefficients (SHGC) be determined for the overall
fenestration product (including the sash and frame) in accordance with ISO 15099. The building envelope
trade-off option in §4.4 requires the use of visible light transmittance (VLT).
In several cases, ISO 15099 suggests that individual national standards will need to be more specific and in other
cases the ISO document gives users the choice of two options. This section clarifies these specific issues as they
are to be implemented for this code:
§4.1 of ISO 15099: For calculating the overall U-factor, ISO 15099 offers a choice between the lineara.
thermal transmittance (4.1.2) and the area weighted method (4.1.3). The area weighted method (4.1.3)
shall be used
§4.2.2 of ISO 15099: Frame and divider SHGC’s shall be calculated in accordance with §4.2.2b.
§6.4 of ISO 15099 refers the issue of material properties to national standards. Material conductivitiesc.
and emissivities shall be determined in accordance with Indian standards
§7 of ISO 15099 on shading systems is currently excludedd.
§8.2 of ISO 15099 addresses environmental conditions. The following are defined for India:e.
For U-factor calculations:
Tin = 24°C
Tout = 32°C
V = 3.35 m/s
Trm,out=Tout
Trm,in=Tin
Is=0 W/m2
For SHGC calculations:
Tin = 24°C
Tout = 32°C
V = 2.75 m/s
Trm,out=Tout
Trm,in=Tin
Is=783 W/m2
§8.3 of ISO 15099 addresses convective film coefficients on the interior and exterior of the windowf.
product. In §8.3.1 of ISO 15099, simulations shall use the heat transfer coefficient based on the center
of glass temperature and the entire window height; this film coefficient shall be used on all indoor
surfaces, including frame sections. In §8.3.2 of ISO 15099, the formula from this section shall be
applied to all outdoor exposed surfaces
§8.4.2 of ISO 15099 presents two possible approaches for incorporating the impacts of self-viewingg.
surfaces on interior radiative heat transfer calculations. Products shall use the method in §8.4.2.1 of ISO
15099 (Two-Dimensional Element to Element View Factor Based Radiation Heat Transfer Calculation).
The alternate approach in §8.4.3 of ISO 15099 shall not be used

Default U-factors and Solar Heat Gain Coefficients for11.2
Unrated Fenestration Products
All fenestration with U-factors, SHGC, or visible light transmittance determined, certified, and labeled in
accordance ISO 15099 shall be assigned those values.
Unrated Vertical Fenestration11.2.1
Unlabeled vertical fenestration, both operable and fixed, shall be assigned the U-factors, SHGCs, and visible
light transmittances in Table 11.1
: Defaults for Unrated Vertical Fenestration (Overall Assembly including the Sash andTable 11.1
Frame)
Clear Glass Tinted Glass
Frame Type Glazing
Type
U-factor
(W/m2·K)
SHGC VLT U-factor
(W/m2·K)
SHGC VLT
All frame types Single Glazing 7.1 0.82 0.76 7.1 0.70 0.58
Wood, vinyl, or fiberglass
frame
Double Glazing 3.3 0.59 0.64 3.4 0.42 0.39
Metal and other frame type Double Glazing 5.1 0.68 0.66 5.1 0.50 0.40
Unrated Sloped Glazing and Skylights11.2.2
Unrated sloped glazing and skylights, both operable and fixed, shall be assigned the SHGCs and visible light
transmittances in Table 11.1. To determine the default U-factor for unrated sloped glazing and skylights without
a curb, multiply the values in Table 11.1 by 1.2. To determine the default U-factor for unrated skylights on a
curb, multiply the values in Table 11.1 by 1.6.
Typical Roof Constructions11.3
ForcalculatingtheoverallU-factorof atypicalroof construction,theU-factorsfromthetypicalwallconstruction
type and effective U-factor for insulation shall be combined according to the following equation:

1 1
1
U
U U
Total Roof
Typical Roof Typical Insulation
=
+
where
UTotal Roof : Total U-factor of the roof with insulation
UTypical Roof : U-factor of the roof
UTypical Insulation : U-factor of the effective insulation from Table 11.2
: Defaults for effective U-Factor for Exterior Insulation layers (under review)Table 11.2
Thickness R-value U-factor (W/m2·K)
15 mm (0.5”) 0.70 (4) 1.420
20 mm (0.75”) 1.06 (6) 0.946
25 mm (1.0”) 1.41 (8) 0.710
40 mm (1.5”) 2.11 (12) 0.568
50 mm (2.0”) 2.82 (16) 0.406
65 mm (2.5”) 3.52 (20) 0.284
75 mm (3.0”) 3.70 (21) 0.270

Typical Wall Constructions11.4
For calculating the overall U-factor of a typical wall construction, the U-factors from the typical wall construction
type and effective U-factor for insulation shall be combined according to the following equation:

U
U U
1 1
1
Total Wall
Typical Wall Typical Insulation
=
+
where
UTotal Wall : Total U-factor of the wall with insulation
UTypical Wall : U-factor of the wall from
UTypical Insulation : U-factorof theeffectiveinsulationfromTable11.3orTable11.4
: Defaults for effective U-factor for Exterior Insulation Layers (under review)Table 11.3
Thickness R-value U-factor (W/m2·K)
15 mm (0.5”) 0.70 (4) 1.262
20 mm (0.75”) 1.06 (6) 0.874
25 mm (1.0”) 1.41 (8) 0.668
40 mm (1.5”) 2.11 (12) 0.454
50 mm (2.0”) 2.82 (16) 0.344
65 mm (2.5”) 3.52 (20) 0.277
75 mm (3.0”) 3.70 (21) 0.264

Appendix D: Building Envelope Tradeoff Method
Energy Conservation Building Code (ECBC) User Guide D.1
APPENDIX D: Building Envelope Tradeoff
Method
The Envelope Performance Factor12.1
The envelope performance factor shall be calculated using the fol-12.1.1
lowing equations.
Equation 12 1:
where
EPF EPF EPF EPFTotal Roof Wall Fenest= + +
EPF C U ARoof Roof S S
S
n
1
=
=
/
EPF C U A C U A,,Wall Wall Mass S S
S
n
Wall Other S S
S
n
11
= +
==
/ /
EPF C SHGC M A C U A
C SHGC M A C U A
C SHGC M A C U A
,,
,,
,,
Fenest Fenest North W W W
W
n
Fenest North W W
W
n
Fenest NonNorth W W W
W
n
Fenest NonNorth W W
W
n
SSStseneF
S
n
Fenest S S
S
n
thgilykSthgilykS
1
1
2
1
1
1
2
1
1
1
2
1
++=
+ +
+
==
==
==
/ /
/ /
/ /
where
EPFRoof : Envelope performance factor for roofs. Other subscripts include walls and fenestration.
As, Aw : The area of a specific envelope component referenced by the subscript “s” or for windows
the subscript “w”.
SHGCw : The solar heat gain coefficient for windows (w). SHGCs refers to skylights.
Mw : A multiplier for the window SHGC that depends on the projection factor of an overhang
or sidefin.
Us : The U-factor for the envelope component referenced by the subscript “s”
CRoof : A coefficient for the “Roof” class of construction
CWall : A coefficient for the “Wall”
C1 Fenest : A coefficient for the “Fenestration 1”
C2 Fenest : A coefficient for the “Fenestration 2”
Values of “c” are taken from Table 12.1 through Table 12.5 for each class of construction.
: Envelope Performance Factor Coefficients-Composite Climate (under review)Table 12.1
Daytime Occupancy 24-Hour Occupancy
U-factor SHGC U-Factor SHGC
Mass Walls 6.01 - 13.85 -
Curtain Walls, Other 15.72 - 20.48 -

Roofs 11.93 - 24.67 -
North Windows -1.75 40.65 -4.56 58.15
Non-North Windows -1.25 54.51 0.68 86.57
Skylights -96.35 311.71 -294.66 918.77
: Envelope Performance Factor Coefficients-Hot Dry Climate (under review)Table 12.2
Mass Walls 5.48 - 15.01 -
Roofs 11.14 - 25.98 -
North Windows -2.40 36.57 -1.49 56.09
Non-North Windows -1.86 46.79 1.187 81.79
Skylights -96.27 309.33 -295.81 923.01
: Envelope Performance Factor Coefficients-Hot Humid Climate (under review)Table 12.3
Mass Walls 6.42 - 9.60 -
Roofs 9.86 - 14.11 -
North Windows -1.58 34.95 -7.29 64.19
Non-North Windows -1.00 43.09 -6.48 76.83
Skylights -96.11 305.45 -295.45 893.55
: Envelope Performance Factor Coefficients-Moderate Climate (under review)Table 12.4
Mass Walls 2.017 - 3.11 -
Roofs 5.46 - 5.86 -
North Windows -3.10 29.66 -11.95 62.14
Skylights -96.21 298.82 -294.12 876.70
: Envelope Performance Factor Coefficients-Cold Climate (under review)Table 12.5
Mass Walls 5.19 - 5.19 -
Roofs 5.69 - 5.67 -
North Windows 1.55 9.13 1.55 9.13
Skylights -93.44 283.18 -93.44 283.18
Overhang and Side Fin Coefficients12.1.2
The “M” multiplication factor can also be calculated using Equation 12 2. If the equation is used, a separate
calculation shall be made for each orientation and unique shading condition.
Equation 12 2: M a PF b PF 12
= + +· ·

: Overhang and Side Fin CoefficientsTable 12.6
Device Coefficient North South East/West
Overhangs A 0.16 0.21 0.10
B -0.61 -0.83 -0.58
Side Fins A 0.23 0.12 0.14
B -0.74 -0.59 -0.52
Example 12.1: Calculation Showing ECBC Compliance Using Trade-Off Op-
tion
Description of building:
Building size: 40m length, breadth 25m, 3m height, having 10sqm fenestration on each façade.
Location: Hot and dry climatic zone
Determination of upper limit of envelope performance factor (EPF) for wall, roof and fenestrationStep 1:
using prescriptive values:
EPF C U ARoof Roof S S
S
n
1
=
=
/a)
Us (from table 4.1) = 0.261 (for 24 hr building)
As (as per geometry) = 40 x 25 = 1000 m2
CRoof (from table 12.2) = 25.98 (for 24 hr building in hot and dry climate)
EPFRoof = 25.98 × 0.261 × 1000
= 6780.78
EPF C U A C U A,,Wall Wall Mass S S
S
n
Wall Other S S
S
n
11
= +
==
/ /b)
(In this case it has been assumed that there is no curtain wall)
Us (from table 4.2) = 0.440
As (as per geometry) = 390 m2
CWall (from table 12.2) = 15.01
EPFWall = 15.01 × 0.44 × 390
= 2575.71

EPF C SHGC M A C U A
C SHGC M A C U A
C SHGC M A C U A
1 ,
1
2 ,
1
1 ,
1
2 ,
1
1 ,
1
2 ,
1
Fenest Fenest North W W W
W
n
Fenest North W W
W
n
Fenest NonNorth W W W
W
n
Fenest NonNorth W W
W
n
Fenest Skylight W W W
W
n
Fenest Skylight S S
S
n
++=
+ +
+
==
==
==
/ /
/ /
/ /
c)
(Assuming there is no skylight and no shading device used on windows)
UW (from table 4.3) = 3.3
SHGC (from table 4.3) = 0.25 (since WWR < 40%)
MW = 1 (for no overhang case, in case of overhang, MW is to be calculated using table
12.6) and equation 12.2of ECBC
C1 Fenest, North (from table 12.2) = 56.09
C2 Fenest, North (from table 12.2) = -1.49
C1 Fenest,Non North(from table 12.2) = 81.79
C2 Fenest, Non North (from table 12.2) = 1.187
EPFFenest = 56.09 × 0.25 × 10 + (-1.49) × 3.3 × 10 + 81.79 × 0.25 × 30 + 1.187 × 3.3 × 30
= 821.98
EPFTotal = EPFRoof + EPFwall + EPFFenest
= 6780.78 + 2575.71 + 821.98
= 10178.47
Determination of EPF of proposed building using actual U-factors and SHGC.Step 2:
Assuming that in place of using Uroof of 0.261, the roof of proposed building has U-factor of 0.3.
EPFroof new = 25.98 × 0.3 × 1000
= 7794
Similarly if U-factor of wall/fenestration and SHGC are different from prescriptive requirement, new EPFwall,
EPFFenest are to be calculated.
In this case, let us first assume that the wall and fenestration meet the prescriptive requirements.
The EPF of proposed building is:
EPFTotal new = 7794 + 2575.71 + 821.98
= 11191.69
Comparison of EPF through perspective route and EPFStep 3: new through actual specifications show the
later is higher than the EPFperspective. Hence the building is not complying with the ECBC.
Now even with the roof having inferior U- value (0.4 against the requirement of 0.261), the EPFStep 4:
is to be brought down to the level of EPFperspective i.e. 10178.47 in this case. This may be done by several
options related to wall or fenestration.
In the example given above, through back calculation, it can be found that for bringing down the EPFnew to
the level of EPFprescriptive= 10178.47 and with EPFRoof being 7794, and no change in fenestration, (EPFFenest

=821.98), the maximum EPFWall can be :
EPFWall new = 10178.47 – 7794 -821.98
= 1562.02
For the target EPFStep 5: Wall new =1562.02, the required UWall new can be calculated through back
calculation:-
EPFwall = EPF C U A
1
Wall Wall S S
S
n
=
=
/
Uwall =
.
.
0.266U 15 01 390
1562 01
Wall
#= =
This means that due to certain limitation if in place of having U-factors of roof equal to 0.261, it is kept as
0.3, as one option, U-factor of wall can be improved from 0.44 to 0.266 for complying with the code. Similar
to the method of calculating revised U-factor for wall, other alternatives such as change in SHGC or change in
UFenest can also be explored.
Important: Change in specification through trade-off method would vary from case-to-case and therefore
need to be calculated separately for individual building and for individual solution.
Baseline Building Definition12.1.3
The following rules shall be used to define the Baseline Building for Envelope Tradeoff:
The Baseline Building shall have the same building floor area, gross wall area and gross roof area as thea.
proposed design. If the building has both 24-hour and daytime occupancies, the distribution between
these shall be the same as the proposed design
The U-factor of each envelope component shall be equal to the criteria from §4.3 for each class ofb.
construction
The vertical fenestration area shall be equal to the proposed design or 40% of the gross exterior wallc.
area, which ever is less. The skylight area shall be equal to the proposed design or 5% of the gross
exterior roof area, which ever is less
The SHGC of each window or skylight component shall be equal to the criteria from §4.3d.

Appendix E: Climate Zone Map of India
Energy Conservation Building Code (ECBC) User Guide E.1
APPENDIX E: Climate Zone Map of India
Climate Zones13.1
The first step in following the ECBC is determining the appropriate climate zone of the building site
which will dictate the specific requirements for design and construction of the building systems and
components. India possesses a large variety of climates, which can be broadly categorized into five regions
with distinct climates. The five climate zones, illustrated in the following map are normally designated as hot
and dry, warm and humid, composite, temperate, and cold. The classification of climate for different types of
buildings is an aid to the functional design of buildings. Our country is zoned into several regions such that
the differences of climate from region to region are capable of being reflected in building design, warranting
some special provision for each region.
The significant difference in the climatic data across these zones defines unique thermal comfort requirements
for buildings located in different zones. Following broadly highlights the differences in weather data in the
five climate zones and Table 13.2 provides a list of major cities in India with respect to their climate zones.
These differences in the weather profile translate into unique requirements for building thermal comfort and
architectural responses for the different climate zones. (See in Figure 13.1).
: Climate Zone MapFigure 13.1

:Table13.1ClassificationsofDifferentClimateZonesinIndia
Climate
Zone
DescriptionMeanTemperature(°C)Mean
Relative
humidity
Annual
Precipitation
Sky
Conditions
Places
Summer
midday
(High)
Summer
night
(Low)
Winter
midday
(High)
Winter
night
(Low)
Diurnal
Variation
Hotand
Dry
Hightemperature|Lowhumidityandrainfall|Intense
solarradiationandagenerallyclearsky|Hotwinds
duringthedayandcoolwindsatnight|Sandyorrocky
groundwithlittlevegetation|Lowundergroundwater
tableandfewsourcesofsurfacewater.
40to4520to305to250to1015to20VeryLow
25-40%
Low<500mm/
yr.
Cloudless
skieswithhigh
solarradiation,
causingglare
Rajasthan,
Gujarat,West-
ernMadhya
Pradesh,Central
Maharashtraetc.
Warmand
Humid
Temperatureismoderatelyhighduringdayandnight
|Veryhighhumidityandrainfall|Diffusedsolarra-
diationifcloudcoverishighandintenseifskyisclear
|Calmtoveryhighwindsfromprevailingwinddirec-
tions|Abundantvegetation|Provisionfordrainage
ofwaterisrequired
30to3525to3025to3020to255to8High70to
90%
High>1200
mm/yr.
Overcast(cloud
coverranging
between40and
80%),causing
unpleasantglare
Kerela,Tamil-
nadu,Costalparts
ofOrissaand
AndhraPradesh
etc.
TemperateModeratetemperature|Moderatehumidityand
rainfall|Solarradiationsamethroughouttheyear
andskyisgenerallyclear|Highwindsduring
summerdependingontopography|Hillyorhigh
plateauregionwithabundantvegetation
30to3417to2427to3316to188to13High60to
85%
High>1000
mm/yr
Mainlyclear,
occasionally
overcastwith
denselowclouds
insummer
Bangalore,Goa
andpartsofthe
Deccan
Cold
(Sunny/
Cloudy)
Moderatesummertemperaturesandverylowin
winter|Lowhumidityincold/sunnyandhigh
humidityincold/cloudy|Lowprecipitationincold/
sunnyandhighincold/cloudy|Highsolarradiation
incold/sunnyandlowincold/cloudy|Coldwinds
inwinter|Verylittlevegetationincold/sunnyand
abundantvegetationincold/cloudy
17to
24/20to
30
4to
11/17to
21
(-7)to8
/4to8
(-14)to
0/(-3)
to4
25to25/5
to15
Low:10-
50%/High:
70-80%
Low:<
200mm/
yr/Moderate
1000mm/yr
Clearwithcloud
cover<50%/
Overcastfor
mostoftheyear
Jammu&Kash-
mir,Ladakh,Hi-
machalPradesh,
Uttaranchal,Sik-
kim,Arunachal
Pradesh
CompositeThisapplieswhen6monthsormoredonotfallwithin
anyoftheabovecategories|Hightemperature
insummerandcoldinwinter|Lowhumidityin
summerandhighinmonsoons|Highdirectsolar
radiationinallseasonsexceptmonsoonshighdiffused
radiation|OccasionalhazyskyHotwindsinsummer,
coldwindsinwinterandstrongwindinmonsoons|
Variablelandscapeandseasonalvegetation
32to4327to3210to254to1035to22Variable
Dry
Periods=
20-50%Wet
Periods=
50-95%
Variable500-
1300mm/yr,
duringmonsoon
reaching250mm
inthewettest
month
Variable
Overcastand
dullinthe
monsoon
UttarPradesh,
Haryana,Punjab,
Bihar,Jharkhand,
Chattisgarh,
MadhyaPradesh
etc.
Sources:BansalandMinke(1988)ClimaticzonesandruralhousinginIndia
Krishanetal.(2001).Climateresponsivearchitecture:AdesignhandbookforEnergy-EfficientBuildings

Table 13.2: Climate Zone of the Major Indian Cities
Indian Cities and their respective Climatic Zones
City Climatic Zone City Climatic Zone
Ahmedabad Hot & Dry Jorhat Warm & Humid
Allahabad Composite Kota Hot & Dry
Amritsar Composite Kurnool Warm & Humid
Aurangabad Hot & Dry Lucknow Composite
Bangalore Temperate Madras Warm & Humid
Barmer Hot & Dry Manglore Warm & Humid
Belgaum Warm & Humid Nagpur Composite
Bhagalpur Warm & Humid Nellore Warm & Humid
Bhopal Composite New Delhi Composite
Bhubaneshwar Warm & Humid Panjim Warm & Humid
Bikaner Hot & Dry Patna Composite
Bombay Warm & Humid Pune Warm & Humid
Calcutta Warm & Humid Raipur Composite
Chitradurga Warm & Humid Rajkot Composite
Dehra Dun Composite Ramgundam Warm & Humid
Dibrugarh Warm & Humid Ranchi Composite
Gauhati Cold Ratnagiri Warm & Humid
Gorakhpur Composite Raxaul Warm & Humid
Gwalior Composite Saharanpur Composite
Hissar Composite Shillong Warm & Humid
Hyderabad Composite Sholapur Hot & Dry
Imphal Warm & Humid SunderNagar Cold
Indore Composite Surat Hot & Dry
Jabalpur Composite Tezpur Warm & Humid
Jagdelpur Warm & Humid Tiruchchirapalli Warm & Humid
Jaipur Composite Trivandrum Warm & Humid
Jaisalmer Hot & Dry Tuticorin Warm & Humid
Jamnagar Warm & Humid Veraval Warm & Humid
Jodhpur Hot & Dry Vishakhapatnam Warm & Humid

Appendix F: Air-Side Economizer Acceptance Procedures Envelope Summary
Energy Conservation Building Code (ECBC) User Guide F.1
APPENDIX F: Air-Side Economizer
Acceptance Procedures
Construction Inspection14.1
Prior to Performance Testing, verify and document the following:
System controls are wired correctly to ensure economizer is fully integrated (i.e. economizer will operate•
when mechanical cooling is enabled)
Economizer lockout control sensor location is adequate (open to air but not exposed to direct sunlight•
nor in an enclosure; away from sources of building exhaust; at least 8 m [25 ft] away from cooling
towers)
System is provided with barometric relief, relief fan or return fan to control building pressure•
Equipment Testing14.2
Simulate a cooling load and enable the economizer by adjusting the lockout control setpoint. VerifyStep 7:
and document the following:
Economizer damper modulates opens to 100% outside air•
Return air damper modulates closed and is completely closed when economizer damper is 100% open•
Economizer damper is 100% open before mechanical cooling is enabled•
Relief fan or return fan (if applicable) is operating or barometric relief dampers freely swing open•
Continue from Step 1 and disable the economizer by adjusting the lockout control setpoint. VerifyStep 8:
and document the following:
Economizer damper closes to minimum ventilation position•
Return air damper opens to at or near 100%•
Relief fan (if applicable) shuts off or barometric relief dampers close. Return fan (if applicable) may•
still operate even when economizer is disabled

Appendix G: Compliance Forms
Energy Conservation Building Code (ECBC) User Guide G.1
APPENDIX G: ECBC Compliance Forms
Envelope Summary15.1
Envelope Summary ENVELOPE Summary
2005 India Energy Conservation Building Code Compliance Forms Draft 1, 27 March 2005
Project Info Project Address Date
For Building Department Use
Applicant Name:
Applicant Address:
Applicant Phone:
Project Description
Compliance Option
Total Vertical Fenestration
Area
(rough opening) divided by
Gross Exterior
Wall Area times 100 equals
% Vertical
Fenestration
X 100 =
Total Skylight Area
(rough opening) divided by
Gross Exterior
Wall Area times 100 equals % Skylight
X 100 =
Hospital, hotel, call center (24 hour) Other building type (daytime)
OPAQUE ASSEMBLY OPAQUE ASSEMBLY
Roof m Insulation R-value Roof m Insulation R-value
Wall m Insulation R-value Wall m Insulation R-value
FENESTRATION FENESTRATION
Vertical Vertical
Maximum U-factor Maximum U-factor
Maximum SHGC (or SC) Maximum SHGC (or SC)
Overhang (yes or no) Overhang (yes or no)
If yes, enter Projection Factor If yes, enter Projection Factor
Side fins (yes or no) Side fins (yes or no)
If yes, enter Projection Factor If yes, enter Projection Factor
Skylight Skylight
Maximum U-factor Maximum U-factor
Maximum SHGC (or SC) Maximum SHGC (or SC)
Vertical Fenestration Area
Calculation
Skylight Area Calculation
Note: Vertical fenestration area can not exceed
40% of the gross wall area for prescriptive option
New Building Addition Alteration Change of Use
Prescriptive Envelope Trade-Off (Appendix D) Systems Analysis
Hospital, hotel, call center (24 hour) Other building types (daytime)
Note: Skylight area can not exceed 5% of the gross
roof area for prescriptive compliance.

Building Permit Plans Checklist15.2
Building Permit Plans Checklist ENVELOPE Checklist
Project Address Date
Applicability Code Location Building Department
(yes, no, n.a.) Section Component Information Required on Plans Notes
MANDATORY PROVISIONS (Section 4.2)
4.2.1 Fenestration rating
4.2.1.1 U-factor Specify whether per 4.2.1.1 or default in Appendix C
4.2.1.2 SHGC Specify whether per 4.2.1.2 or default in Appendix C
4.2.1.3 Air leakage Specify leakage rates
4.2.2 Opaque U-factors Specify whether per default in Appendix C or ASHRAE
4.2.3 Bldg. env. sealing Indicate sealing, caulking, gasketing, and weatherstripping
PRESCRIPTIVE COMPLIANCE OPTION (Section 4.3)
4.3.1 Roof Indicate R-values on roof sections
4.3.2 Cool roof Indicate minimum reflectance and emittance on plans
4.3.3 Roof Indicate R-values on wall sections
4.3.4 Vertical fenestration
(1) Indicate U-factors on fenestration schedule. Indicate if
values are rated or default. If values are default, then specify
frame type, glazing layers, gapwidth, low-e.
(2) Indicate SHGC or SC on fenestration schedule. Indicate if
values are rated or default.
(3) Indicate if overhangs or side fins are used for compliance
purposes. If so, provide projection factor calculation.
4.3.5 Skylights
(1) Indicate U-factors on fenestration schedule. Indicate if
values are rated or default. If values are default, then specify
frame type, glazing layers, gapwidth, low-e.
(2) Indicate SHGC or SC on fenestration schedule. Indicate if
values are rated or default.
BUILDING ENVELOPE TRADE-OFF OPTION (Section 4.4)
Provide calculations
The following information is necessary to check a building permit application for compliance with the building envelope requirements in the
2005 India Energy Conservation Building Code.

Mechanical Summary15.3
Mechanical Summary MECHANICAL Summary
Project Info Project Address
For Building Dept. Use
Applicant Name:
Applicant Address: 0
Applicant Phone: 0
Project Description
Briefly describe mechanical
system type and features.
FALSE
Compliance Option
Equipment Schedules
Cooling Equipment Schedule
Equip.
ID Brand Name Model No.
Capacity
kW Total L/s
OSA CFM
or Econo?
SEER
or EER IPLV Location
Heating Equipment Schedule
Equip.
ID Brand Name Model No.
Capacity
kW Total L/s
OSA cfm
or Econo? Input kW Output kW Efficiency
Fan Equipment Schedule
Equip.
ID Brand Name Model No. Total L/s SP kW Flow Control Location of Service
The following information is required to be incorporated with the mechanical equipment schedules on the plans.
For projects without plans, fill in the required information below.
Simple System Complex System Systems Analysis
Includes Plans
Date

Mechanical Permit Checklist15.4
Mechanical Permit Checklist MECHANICAL Checklist
HEATING, VENTILATING, AND AIR CONDITIONING (Chapter 5)
5.2.1 Equipment effficiency Provide equipment schedule with type, capacity, efficiency
5.2.2 Controls
5.2.2.1 Timeclocks
Indicate thermostat with night setback, 3 different day types,
and 2-hour manual override
5.2.2.2 Temp. & deadband
Indicate temperature control with 3 degree C deadband
minimum
5.2.2.3 Clg.tower, fluid cooler
Indicate two-speed motor, pony motor, or variable speed drive
to control the fans
5.2.3 Piping & ductwork Indicate sealing, caulking, gasketing, and weatherstripping
5.2.3.1 Piping insulation Indicate R-value of insulation
5.2.3.2 Ductwork insulation Indicate R-value of insulation
5.2.3.3 Ductwork sealing Specify sealing types and locations
5.2.4 System balancing Specify system balancing
PRESCRIPTIVE COMPLIANCE OPTION (Section 5.3)
5.3
Indicate whether project is complying with ECBC Prescriptive
Option OR with ASHRAE Standard 90.1-2004
5.3.1 Economizer
5.3.3.1 Air economizer Indicate 100% capability on schedule
5.3.3.2 Integrated operation Indicate capability for partial cooling
5.3.3.3 Field testing Specify tests
5.3.2 Variable flow hydronic
5.3.3.1 Pump flow rates Indicate variable flow capacity on schedules
5.3.3.2 Isolation valves Indicate two-way automatic isolation valves
5.3.3.3 Variable speed drive Indicate variable speed drive
SERVICE WATER HEATING AND PUMPING (Chapter 6)
6.2.1 Solar water heating Provide calculations to justify capacity to meet 20% threshold
6.2.2 Equipment effficiency Provide equipment schedule with type, capacity, efficiency
6.2.3 Piping insulation Indicate R-value of insulation
6.2.4 Heat traps
Indicate heat trap on drawings or provide manufacturers
specifications to show that equipment has internal heat trap
6.2.5 Pool covers Provide vapor retardant cover for pools
6.2.5 Pools over 32 C Provide R-2.1 insulation
The following information is necessary to check a building permit application for compliance with the mechanical requirements in the 2005
India Energy Conservation Building Code.

Lighting Summary15.5
Lighting Summary LIGHTING Summary
Project Info Project Address Date
For Building Department Use
Applicant Name:
Applicant Address: 0
Applicant Phone:
Project Description
Compliance Option
Alteration Exceptions Less than 50% of the fixtures are new and installed lighting wattage is not being increased
(check box, if appropriate)
Maximum Allowed Lighting Wattage (Interior, Section 7.3)
Location
(floor/room no.) Occupancy Description
Allowed
Watts per m
2
** Area in m
2
Allowed x Area
0.0
0.0
0.0
** Document all exceptions Total Allowed Watts 0.0
Proposed Lighting Wattage (Interior)
Location
(floor/room no.) Fixture Description
Number of
Fixtures
Watts/
Fixture
Watts
Proposed
0.0
0.0
0.0
Total Proposed Watts may not exceed Total Allowed Watts for Interior Total Proposed Watts 0.0
Maximum Allowed Lighting Wattage (Exterior, Section 7.4)
Location Description
Allowed Watts
per m
2
or per lm
Area in m
2
(or lm for perimeter)
Allowed Watts
x m
2
(or x lm)
0.0
0.0
0.0
0.0
0.0
Total Allowed Watts 0.0
Proposed Lighting Wattage (Exterior)
Location Fixture Description
Number of
Fixtures
Watts/
Fixture
Watts
Proposed
0.0
0.0
0.0
Total Proposed Watts may not exceed Total Allowed Watts for Exterior Total Proposed Watts 0.0
Change of UseNew Building Addition Alteration
Prescriptive Systems Analysis

Lighting Permit Checklist15.6
Lighting Permit Checklist LIGHTING Checklist
LIGHTING (Chapter 7)
7.2.1 Controls
7.2.1.1 Automatic shutoff Indicate automatic shutoff locations or occupancy sensors
7.2.1.2 Space control Provide schedule with type, indicate locations
7.2.1.3 Daylight zones Provide schedule with type and features, indicate locations
7.2.1.4 Ext. lighting control Indicate photosensor or astronomical time switch
7.2.1.5 Additional control Provide schedule with type, indicate locations
7.2.2 Tandem wiring Show wiring on schedule
7.2.3 Exit signs Indicate 5 watts maximum
7.2.4 Ext. bldg.grounds ltg. Indicate minimum efficacy of 60 lumens/Watt
PRESCRIPTIVE INTERIOR LIGHTING POWER COMPLIANCE OPTION (Section 7.3)
7.3
Indicate whether project is complying with the Building Area
Method (7.3.1) or the Space Function Method (7.3.2)
7.3.1 Building area method
Provide lighting schedule with wattage of lamp and ballast and
number of fixtures. Document all exceptions.
7.3.2 Space function method
7.3.3 Luminaire wattage Indicate on plans
PRESCRIPTIVE EXTERIOR LIGHTING POWER COMPLIANCE OPTION (Section 7.4)
7.4 Building area method
ELECTRICAL POWER (Chapter 8)
8.2.1 Transformers Provide schedule with transformer losses
8.2.2 Motor efficiency Provide equipment schedule with motor capacity, efficiency
8.2.3 Power factor correctionProvide schedule with power factor correction
8.2.4 Check metering Provide check metering and monitoring
The following information is necessary to check a building permit application for compliance with the lighting requirements in the 2005 India
Energy Conservation Building Code.

Whole Building Performance Checklist15.7
Whole Building Performance Method Compliance Report
Project Name
Project Address Date:
Designer of Record: Telephone:
Contact person: Telephone:
City:
Weather Data:
Climate Zone:
Total Conditioned Area (sq ft) Total Unconditioned Area (sq ft) Total Floor Area (sq ft)
Advisory messages
Proposed Design Standard Design Difference
Number of hours of heating loads unmet (system/plant)
Number of hours of cooling loads unmet (system/plant)
Number of warnings
Number of errors
Number of defaults overridden
Additional Building Information
Number of floors
Simulation program
Comparison of Input Parameters in Proposed Design and Standard Design
Building Element Proposed Design Input Standard Design Input
Envelope
Above Grade Wall Construction(s)
Below Grade Wall Construction
Roof Construction
Exterior Floor Construction
Slab-on-Grade Construction
Window-to-Gross Wall Ratio
Fenestration Type(s)
Fenestration Assembly U Factor
Fenestration Assembly SHGC
Fenestration Visual Light Transmittance
Fixed Shading Devices
Automated Movable Shading Devices
Electrical System & Process Loads
Ambient lighting power density and Lighting
Design Description.
Process Lighting
Lighting occupant Sensor Controls
Day lighting Controls

Receptacle Equipment
Elevators or Escalators
Refrigeration Equipment
Other Process loads
Mechanical & Plumbing Systems
HVAC System Type (s) Variable Air Volume Constant Air Volume
Design Supply Air Temperature Differential
Fan Control
Fan Power
Economizer Control
Demand Control Ventilation
Unitary Equipment Cooling Efficiency
Unitary Equipment Heating Efficiency
Chiller Type, Capacity, And Efficiency
Cooling Tower
Boiler Efficiency
Chilled Water loop and Pump Parameters
Condenser Water loop and Pump Parameters
Hot Water Loop and Pump Parameters
Domestic Hot Water pump Parameters
Standard Design - End Use Summary
End use 0 rotation 90 rotation 180 rotation 270 rotation Average
Energy
Type
Energy
(kWh)
Peak
(kW)
Energy
(kWh)
Peak
(kW)
Energy
(kWh)
Peak
(kW)
Energy
(kWh)
Peak
(kW)
Energy
(kWh)
Peak
(kW)
Interiors
Lighting
Elec
Interior lighting
(Process)
Elec
Exterior
Lighting
Elec
Space heating
(Fuel 1)
Natural
Gas
Space heating
(Fuel 2)
Elec
Space Cooling Elec
Pumps Elec
Heat Rejection Elec
Fans Interior Elec
Fans Parking
garage
Elec
Service Water
Heating (Fuel
1)
Natural
Gas
Service Water
Heating (Fuel
2)
Elec
Receptacle
Equipment
Elec
Refrigeration
(Food, etc.,)
Elec

Cooking
(commercial,
fuel 1)
Elec
Cooking
(commercial,
fuel 2)
Elec
Elevators and
Escalators
Elec
Other Process Elec
Total Building
Consumption/
Demand
Elec
Total Process
Energy
Elec
Energy Summary by End Use
Proposed Design Standard Design
End Use Energy Type Energy
(kWh)
Peak
(kW)
Energy
(kWh)
Peak
(kW)
Energy
(%)
Interior Lighting (Ambient) Electricity
Interior lighting (Process) Electricity
Exterior Lighting Electricity
Space Heating (fuel 1) Natural gas
Space Heating (fuel 2) Electricity
Space Cooling Electricity
Pumps Electricity
Heat Rejection Electricity
Fans - Interior Electricity
Fans-Parking Garage Electricity
Service Water Heating (fuel 1) Natural Gas
Service Water Heating (fuel 2) Electricity
Receptacle Equipment Electricity
Refrigeration (food, etc.,) Electricity
Cooking (commercial, fuel 1) Natural Gas
Cooking (commercial, fuel 2) Electricity
Elevators and Escalators Electricity
Other Process Electricity
Total Building Consumption
Proposed Design Standard Design Percentage Improvement
Type Energy Use
(kWh)
Energy Use
(kWh)
Energy
(%)
Nonrenewable (Regulated & Unregulated)
Electricity 2583,826 2624,623 1.55%
Natural Gas - - -
Steam or Hot water - - -
Chilled Water - - -
Other - - -
Total Nonrenewable Regulated &
Unregulated)
2583,826 2624,623 1.55%

Appendix H: Comparison of International Building Energy Standards
Energy Conservation Building Code (ECBC) User Guide H.1
APPENDIX H: Comparison Of International
Building Energy Standards1
Buildings account for about one-third of all the energy consumption in the world, and much of this con-
sumption footprint is locked in through the design and construction of the building.2 Building energy
standards are an important tool to improve energy efficiency in new buildings. For example, China’s residential
energy standard requires new buildings to be 65% more efficient than buildings from the early 1980s. In the
U.S., building energy codes3 save over $1 billion in energy costs per year, and this figure is growing.4 Denmark
adopted one of the first comprehensive building energy codes in 1961, and it has seen average household en-
ergy consumption per unit of space drop substantially since then. 5 Building energy standards set requirements
for how energy-efficient a building will be. Standards vary quite a bit between countries in several respects
including the extent of their coverage, the specific requirements, means of attaining compliance and the en-
forcement system. This summary provides an overview of some key trends in building energy standards, and
what this may mean for India.
Extent of Coverage
Building energy standards at a minimum usually cover insulation and thermal and solar properties of the building
envelope (the walls, roofs, windows and other points where the interior and exterior of a building interface).
Most standards also cover heating, ventilation, and air conditioning, hot water supply systems, lighting, and
electrical power. Some cover additional issues such as the use of natural ventilation and renewable energy, and
building maintenance. In some countries, not all the issues are considered in a single standard. For example,
the Chinese standards include lighting in a separate document. Within these broad categories, there are also
numerous differences in what the specific requirements cover. Some countries have significant detail about the
need to minimize condensation on insulation. Some countries (like India or Japan) have detailed requirements
based on different types, sizes or orientations of buildings, for example, while others have simpler requirements
for a broader range of buildings. The U.S., India, and Canada all have commercial building energy codes derived
from standards produced by the American Society of Heating, Refrigerating and Air Conditioning Engineers
(ASHRAE), although specific requirements in each country vary. European Union countries are all required to
adopt legislation harmonized with the Directive on Energy Performance in Buildings, which provides guidelines
for the performance of buildings including the envelope, HVAC, lighting (in non-residential), building orientation
and passive solar systems.
Comparison of Elements Covered in Selected Commercial Building Standards and Codes
Australia Canada China India Japan Korea U.S. (ASHRAE
90.1 2007)
Envelope × × × × × × ×
HVAC × × × × × × ×
Service Hot Water and
Pumping
× × N.A. × × × ×
Electrical Power × × N.A. × N.A. × ×
Lighting × × N.A., in a sepa-
rate standard
× × × ×
Performance-Based
Alternative
× × N.A. × × × ×
1 Content Credit: M Evans, B Shui, A Delgado, Pacific Northwest National Laboratory (PNNL), USA.
2 This report is primarily based on a series of country reports describing building energy codes in the Asia-Pacific region that the Pacific
Northwest National Laboratory prepared with U.S. Department of Energy support under the Asia-Pacific Partnership on Clean Develop-
ment and Climate.
3 Some countries refer to their building energy regulations as codes and others call them standards.
4 Please see www.energycodes.gov for details.
5 Jens Lausten. 2008. Energy Efficiency Requirements in Building Codes, Energy Efficiency Policies for New Buildings. International Energy
Agency, Paris.

Not all standards and codes cover the same types of buildings either. For example, in India, the Energy
Conservation Building Code (ECBC) covers commercial and multi-family residential buildings, but not small
residential buildings; this is also true of the standards in Russia, Ukraine, and Kazakhstan, for example. In
Japan, there are standards for both residential and commercial buildings, but the buildings must have at least
2,000 square meters of floor space to be covered. Most countries that regulate both commercial and residential
construction for energy efficiency have separate standards for each, although countries categorize the buildings
differently. In India, Australia, Canada, and the U.S., the codes consider commercial buildings to include multi-
family residential buildings, while in China and Japan, the residential standards regulate such multi-family
residences. This difference is important because typically the commercial building requirements are somewhat
more complex and cover more issues than those for residential buildings.
Specific Requirements
The actual efficiency requirements for new buildings vary between countries. While it would not be possible to
highlight the full range of variation in a summary of this size, a few examples may help to illustrate this point.
The table below highlights differences between the requirements for several building components in India,
Australia, China and the U.S.
Snapshot of Building Energy Efficiency: Maximum U-Factors and Lighting Power Densities in the
U.S., China and India [Units: W/(m²·K) for U-factors]
Building Components U.S. China India Australia
Miami Hainan New Delhi Darwin
Roof 0.358 0.9 0.409 for most buildings;
0.261 for 24-hr buildings
0.313
Wall 0.642 to 3.293 1.5 0.44 0.556
Vertical Glass Windows (SHGC) 0.25 0.35 to 0.60 0.20 to 0.25 0.09
Lighting Power Density (W/m²) 10.8 11 10.8 7 or 10
Notes: This table assumes that we are comparing a 10-story commercial office building in similar climate zones
in each country. The representative cities used for the comparison are Miami in the U.S., Hainan Province in
China, and New Delhi in India. SHGC stands for solar heat gain coefficient and it represents the ratio of solar
heat that can penetrate through a window. WWR stands for window to wall ratio.
Sources: ASHRAE 90.1-2007, ECBC 2007, China’s Design Standards for Energy Efficiency of Public Buildings
2005 and the Building Code of Australia 2007.
In general, the lower the number represented in this chart, the more efficient the component will be. However,
because this chart is looking at one building type in one climate zone, extrapolating these results to a national
level requires some care. For example, the U.S. U-factors shown are quite different than the requirements
applicable in other U.S. climate zones, where more efficient envelopes are mandatory.
Means of Attaining Compliance
Building energy standards typically provide property owners with some degree of flexibility in meeting the
energy efficiency requirements. This is important because it means that the standard can be more stringent
without impinging too severely on the ability of property owners to adapt buildings to their needs. There
are several approaches to providing this flexibility. In many countries, including India, the U.S., Canada and
Australia, the codes have four classes of requirements. The first are mandatory requirements that must be
satisfied regardless of any other factors for a building to be considered in compliance. The majority of these
codes are then made of up prescriptive requirements, which are similar to the mandatory requirements in that
they provide specific values and details. However, building designers may be allowed to “trade-off” some of the
prescriptive requirements with others regarding the building envelope. The codes then provide rules on what
can be traded-off and how. Finally, these codes also provide an option for compliance based on building energy
performance instead of the prescriptive requirements. This last option would allow a building designer to install

less efficient windows but a more efficient air conditioning system if the total designed energy use falls within
the required norms. There are several approaches to establishing the baseline for comparison under the building
energy performance method. The UK uses a total carbon footprint of the building (called the Carbon Index
Rating)6, the U.S. uses the cost as its reference metric, while some other countries define the characteristics of
a reference building for the comparison.
Korea takes a different approach, establishing mandatory requirements and points for a whole range of energy
issues related to buildings. Each new building must have a minimum of 60 points. Buildings that exceed the
minimum point requirement may be eligible for certain benefits, such as relaxation of certain zoning rules.
Enforcement Systems
Enforcement is critical for the standard to have an effect. Not all countries have mandatory building energy
standards. India, for example, has a voluntary code. Japan’s standard is also technically voluntary, although Japan
has recently adopted penalties for non-compliance that blur this distinction. The U.S., Canada, and Australia
all adopt building standards at the local level. Not all jurisdictions in the U.S. and Canada have adopted their
nation’s model building energy code.
Some important issues regarding enforcement and the related impact of the code on energy use include: the
point of compliance (design and/or construction stage), how buildings are checked and by whom, penalties
and other incentives for compliance, training and information on the code, compliance tools such as code
compliance software and inspection checklists, equipment and material testing and ratings.
In the U.S., Canada, Australia, and Korea, for example, the building design must be approved and inspectors
check the building for compliance at least once during construction. In Japan, parts of Europe, and the former
Soviet Union, the checks only occur at the building design stage. China uses a combination of government
employees and certified companies to check building designs and inspect the buildings for compliance. There is
no single answer as to which system produces the highest level of compliance. For example, Japanese officials
believe that Japan attains a high level of compliance in actual construction because Japan has a very well
developed system of training and information dissemination on the building energy standards. Studies in the
U.S. have shown that there, physical inspections result in much higher compliance rates.
The stringency of the national system for testing materials and equipment for their energy efficiency properties
can also have a marked impact on the final energy consumption of a building. Most countries have a system
of certified laboratories that test materials and equipment (like windows and air conditioners), and rate them
for efficiency. These ratings then determine if the equipment in a building meets the building energy standard.
Testing procedures vary between countries, and there is anecdotal evidence that even in countries with well
established systems, ratings can differ by 10% or more based on the testing procedures.
Building energy standard compliance rates vary significantly between countries. What constitutes compliance
may also vary, and not all countries consistently publish compliance data. That said, countries usually have lower
compliance rates soon after they adopt or revise a standard, and when their enforcement system is not fully
developed.
Options for India to Consider
IndiahastakenapurposefulsteptowardimprovedbuildingenergyefficiencyinadoptingtheEnergyConservation
Building Code. The next step is implementing this code, which could require concerted efforts both at the state
and national levels. States would need to decide to adopt the code. The national government could also help
with this learning process by requiring that all new government buildings meet the building energy code. For
example the national government might provide tools to help states and local jurisdictions with enforcement.
India has a well-developed system to enforce other types of building codes, and it might use this system for
enforcing the building energy code as well. Building energy inspectors at the local level might need training, and
local jurisdictions could hire some staff to handle the additional workload. India could also try to simplify the
implementation task by developing code compliance software that allows building developers and inspectors to
6 R.E. Horne et al. 2005. International Comparison of Building Energy Performance Standards. Centre for Design, RMIT University, Mel-
bourne, Australia.

easily check the building design for compliance. Such software could also be designed to automatically develop
inspection checklists. As India gains experience with implementing its code, it might want to modify the code
periodically. Many countries have found that establishing a regular timetable for such modifications can allow
many stakeholders to have input into the process, which in turn, makes the code more feasible to implement.
Indian consumers could benefit from this process as the energy costs in new buildings decline at the same time
that the environmental footprint of these buildings grows smaller.

Appendix I: References
Energy Conservation Building Code (ECBC) User Guide I.1
APPENDIX I: References
A. Bhatia: “1. Course Content (PDH 149), HVAC Design Aspects: Choosing a Right System-Central V/s Compact
Systems”, Herndon, USA
ASHRAE/ANSI standard 62 (2004), “2. Ventilation for Acceptable Indoor Air Quality”, American Society of
Heating, Refrigerating, and Air-conditioning Engineers, Atlanta, USA
ASHRAE / ANSI Standard 55 (2004), “3. Thermal Environmental Conditions for Human Occupancy”, American
Society of Heating, Refrigerating, and Air-conditioning Engineers, Atlanta, USA
ASHRAE Handbook (2005): “4. Fundamentals (SI)”, American Society of Heating, Refrigerating, and Air-
conditioning Engineers, Inc., www.ashrae.org, Atlanta, GA, USA
ASHRAE (2004, 2007): “5. 90.1 User Manual-ANSI/ASHRAE/IESNA Standard 90.1-2004”, American Society
of Heating, Refrigerating, and Air-conditioning Engineers, Inc., www.ashrae.org, Atlanta, GA, USA
ASHRAE (2004): “6. Energy Standard for Buildings Except Low-Rise Residential Buildings”, American Society of
Heating, Refrigerating, and Air-conditioning Engineers, Inc., www.ashrae.org, Atlanta, GA, USA
Bansal and Minke(1988), “7. Climatic zones and rural housing in India”, India
Bureau of Energy Efficiency, Ministry of Power, Government of India (2007): “8. Energy Conservation Building
Code (ECBC)-Revised Version May 2008”, New Delhi, India
Bureau of Energy Efficiency, Ministry of Power, Government of India (2005): “9. Energy Efficiency in Electrical
Utilities”, New Delhi, India
Bureau of Indian Standard (2005): “10. National Building Code of India, Second Revision 2005”, New Delhi,
India
Donald R. Wulfinghoff (1999): “11. Energy Efficiency Manual”, Energy Institute Press, Wheaton, Maryland,
USA
Dr. Ardeshir Madhavi (1995): “12. Fundamentals of Building Physics”, Carnegie Mellon University, Pittsburgh, USA
E Source (2005): “13. E Source Technology Atlas Series- Volume I: Lighting, Volume II: Commercial Space Cooling and
Air Handling, Volume IV: Drive Power”, Boulder, CO, USA.
Goetzler W (2007): “14. Variable Refrigerant Flow Systems”, ASHRAE Journal 49 (4)
Krishan et al. (2001): “15. Climate responsive architecture”, A design handbook for energy efficient buildings,
School of Planning & Architecture (SPA), New Delhi, India
Ministry of Power (2001): “16. Energy Conservation Act”, www.powermin.nic.in, New Delhi, India.
Morrison F. (2004): “17. What’s up with Cooling Tower”, ASHRAE Journal 46 (7), USA.
Nayak and Prajapati (2006): “18. Handbook on Energy Conscious Buildings”, IIT Bombay, Bombay, India
Stein, B., Reynolds, J., Grondzik W., & Kwok, A (2005). “19. Mechanical and Electrical Equipment for Buildings”,
10th Ed. John Wiley & Sons Inc.
U.S. Department of Energy: “20. EnergyPlus Energy Simulation Weather Data”, www.eere.energy.gov, Washington DC
US Green Building Council (2006), “21. LEED for new Construction, Reference Guide, Version 2.2, Third Edition”,
www.usgbc.org, Washington, DC, USA
USAID ECO-III Project: “22. Energy Conservation Building Code Tip Sheet; Envelope, Lighting, HVAC, & Energy
Simulation”, www.eco3.org, New Delhi, India
Web References:
Southface Energy Institute, www.southface.org, 241 Pine Street NE, Atlanta, USA1.

AADI Building, Lower Ground Floor
2, Balbir Saxena Marg, Hauz Khas, New Delhi-110016, India
Phone: +91-11-2685-3110; Email: eco3@irgssa.com; Web Site: www.eco3.org

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