Luminaires – Module 3 Functional Aspects
- 1. Luminaires – An Overview: Facts, Basics and Considerations Target Audience: Facility managers, Procurement managers, Technical managers, Maintenance managers and General Lighting enthusiasts Light-Ref.com The unbiased lighting reference source http://www.light-ref.com © 2012
- 2. Luminaire Overview – Objectives The purpose of this outline is to provide an overview and to familiarize the decision maker with the key considerations when evaluating a lighting solution Luminaire Overview Topics: a. Luminaire classification b. Luminaire technical aspects c. Luminaire functional aspects Light-Ref.com The unbiased lighting reference source http://www.light-ref.com © 2012 2
- 3. Module 3 Luminaire Functional Aspects Light-Ref.com The unbiased lighting reference source http://www.light-ref.com © 2012
- 4. Luminaire – Illumination The optical system of a given luminaire is paramount for meeting the desired illumination. The reflector shape, type, and material are key for light quality in matters of intensity and direction. This section will discuss the following: Illumination basic terms Photometrics, curves & distribution Luminaires and Reflectors efficiency and DLOR (Downward Light Output Ratio) materials, type and reflection louvers and light diffusion Light-Ref.com The unbiased lighting reference source http://www.light-ref.com © 2012 4
- 5. Illumination - Basics The Inverse Square Law of light states that: the power of the light on an object is inversely proportional to the square of the distance (d) from the source … E ~ /d² E – illuminance intensity on a surface. measured in lux. 1m 2m 3m 4m E= 100 lux E= 25 lux E= 11 lux E= 6 lux (100/1²) (100/2²) (100/3²) (100/4²) Light-Ref.com The unbiased lighting reference source http://www.light-ref.com © 2012 5
- 6. Illumination – angle & intensity Intensity measured at 180 pointing towards the ceiling Intensity at 150 Intensity at 90 Intensity values are in cd/1000 lm (lumen) Intensity at 30 cd – candela, luminous Intensity measured at 0 pointing intensity system unit towards the floor Light-Ref.com The unbiased lighting reference source http://www.light-ref.com © 2012 6
- 7. Photometric distribution – polar intensity diagram Polar luminous intensity graph: The diagram illustrates the distribution of luminous intensity, in candelas, of the luminaire. The photometric curve provides a visual guide to the type of light distribution produced by the luminaire e.g. wide, narrow, direct, indirect etc. 150 180 150 The diagram shows Intensity values in the illumination cd/1000 lm against vertical and 120 120 horizontal angles of the luminaire. For 90 90 example, the 100 luminous intensity 200 at 0˚ horizontal 60 60 300 angle and 30˚ 400 vertical angle is 30 0 30 300cd. Light-Ref.com The unbiased lighting reference source http://www.light-ref.com © 2012 7
- 8. Photometric curve types and applications The reflector has a key role in defining the light distribution pattern of a luminaire Light-Ref.com The unbiased lighting reference source http://www.light-ref.com © 2012 8
- 9. Photometrics and IES files Luminaire photometrics is illustrated by an IES file An IES file visually illustrates several dimensions/rotation Any quality luminaire would come with an IES file which can be viewed by a software program rotating it. Commonly used software is IES viewer by http://www.photometricviewer.com Light-Ref.com The unbiased lighting reference source http://www.light-ref.com © 2012 9
- 10. Reflector – Quality and Quantity Illumination The reflector and the optical system of a given luminaire is paramount for meeting the desired illumination. The reflector shape and type, material are key for light quality in matters of intensity and direction. Direct lamp light Reflected lamp light Light-Ref.com The unbiased lighting reference source http://www.light-ref.com © 2012 10
- 11. Reflectors & Lamp size: Efficiency & DLOR T8 vs T5 Fluorescent As a rule of thumb the smaller the lamp the more efficient the reflector would be. DLOR – Downward Light Output Ratio T8 fluorescent diameter is 8/12”, while T5 fluorescent diameter is of 5/12”. The illustration clearly shows that T8 obstructs some of its own light. It is estimated that 5%-10% of T8 light is being obstructed compared with T5. Light-Ref.com The unbiased lighting reference source http://www.light-ref.com © 2012 11
- 12. Reflectors & Lamp Size: Efficiency & DLOR Quartz MH vs. Ceramic MH Quartz MH Ceramic MH bulb: ~ 9”, 23 cm bulb: ~ 3”, 7 cm Light-Ref.com The unbiased lighting reference source http://www.light-ref.com © 2012 12
- 13. Reflector – Size matters Smaller Reflector is considered more advantageous due to the following arguments: • Less material required, eg. cheaper BOM & cheaper logistics • More efficient by design • Higher precision of light orientation illumination • Better quality materials are utilized, due to smaller size • Smaller size design usually more architectural in nature Light-Ref.com The unbiased lighting reference source http://www.light-ref.com © 2012 13
- 14. Reflectors: Material, Type & Reflectance Type Material Reflectance Specular Commercial grade aluminum Up to 0.7 Aluminum with quality coating 0.8-0.9 (based on coating & color) Glass or plastic w’ aluminum 0.85-0.89 coating Multi coated polyester film 0.95-0.98 Spread Brushed aluminum 0.5-0.6 Peened aluminum 0.7-0.8 Diffuse White pain on steel ~ 0.8 (up to) Glossy white plastic ~ 0.9 (up to) Specular Spread Diffuse Light-Ref.com The unbiased lighting reference source http://www.light-ref.com © 2012 14
- 15. Luminaire – light shielding qualities Among luminaire qualities is light shielding. Improved light screening with low cut design is a desirable attribute for a luminaire . Shielding Angle : an angle beyond which light is not visible Cut off Angle : 90 -shielding angle Low cut profile Cut off angle Shielding angle Shielding angle Luminaire A Luminaire B Luminaire “B”, has same cut off angle as “A”, while having low cut profile Light-Ref.com The unbiased lighting reference source http://www.light-ref.com © 2012 15
- 16. Luminaire – light reflection & diffusing Luminaire louvers facilitate light reflection and diffusion aiming to provide pleasant and quality light spread. Ray of light at angle less than shielding angle is diffusely reflected Shielding angle Light-Ref.com The unbiased lighting reference source http://www.light-ref.com © 2012 16
- 17. Luminaire – parabolic reflectors & diffusing Luminaires with parabolic louvers enable orientation and diffusion of light along desired direction. Shielding angle Reflected light rays are oriented along desired direction Light-Ref.com The unbiased lighting reference source http://www.light-ref.com © 2012 17
- 18. The End Luminaires by Light-Ref.com Light-Ref.com The unbiased lighting reference source http://www.light-ref.com © 2012