Thermal Analysis in Ecotect

New York City
College of Technology
The City University of New York
Thermal Analysis in Ecotect
Architectural technology department
written by Nicole Seekely
revised April 20, 2010 3:54 PM

Notes: Material thickness should not be modeled. Zones can be depicted with planar
surface. Be sure you have floors, windows, voids, and partitions assigned properly.
page 2 of 16
For proper thermal analysis,
it is recommended that
you model your geometry
in Ecotect. Importing a
model will result in too much
unnecessary geometry that
will incorrectly inform the
analysis.
All zones in your model
need to be COMPLETELY
enclosed, independently of
other zones around them. In
the example here, the roof of
the green zone, overlaps the
floor of the blue zone - this is
OKAY.

Notes:
page 3 of 16
Make sure all your surface
normals are pointing to the
outside. To check this, go to
Display - Surface Normals.
If the arrows are pointing
inwards, select the element
and use Ctrl+R to reverse
the direction of the normal.
To get rid of the Normals
display, go to Display - Model.
Also, make sure all external
shading devices are on a
non thermal layer such as the
Outside zone.

Notes: You can view the data for the material by double-clicking the material. Click on the
Properties tab to see U-Value, description, and other data. Click on the Layers tab to view
a section of the material and a break-down of the layers.
page 4 of 16
Materials:
For each surface, you should
set a primary and alternative
material. The PRIMARY
material is when the surface
is in contact with the outside.
The ALTERNATIVE material is
when the surface is in contact
with another surface (ie
interior wall).
With the object(s)
selected, go to the Material
Assignments tab. Select both
options when necessary.

Notes: Clicking the arrow to the right of each box will give you recommended values.
page 5 of 16
Zone Settings:
You need to tell Ecotect what
each zone or space is used
for. To do this, go to Model -
Zone Management.
In the Zone Management
window, select a zone on
the left to view it’s default
settings. In the General
Settings tab you can adjust
the clothing factor, lighting
level, number of people,
activity level, etc.

Notes:
page 6 of 16
Zone Settings:
Click on the Thermal
Properties tab to further
adjust settings. Select your
HVAC system, thermostat
range, and hours of
operation.

Notes:
page 7 of 16
Before looking at the Thermal
Analysis, you’ll need to
calculate your Inter-zonal
Adjacencies. This will tell you
if Ecotect understands your
model and will inform you of
any errors. Go to Calculate -
Inter-zonal Adjacencies.
All the default settings should
be okay to use.
More than likely, you’ll have
an error that two objects
sharing a face do not have
the same alternate material.
Be sure to go back and fix
this.

Notes:
page 8 of 16
Lastly, go to the Project tab
on the left side. Check your
data and be sure your North
Offset is set correctly. This
is an easy way to change the
orientation of your building if
it’s not oriented exactly to the
North.

Notes:
page 9 of 16
Go to the Analysis tab on the
left side.
Here you can change
several different options to
do comparison analysis and
gather thermal data for your
building.
The following slides will take
you through a few of the
possible analysis you could
do. Most of this can be
done using the options at the
bottom of the screen.

of 16
Search Data For - Hottest Day
Highlight Zone - Zone 1
Zone Settings - HVAC - Natural Ventilation
With no HVAC system, the inside temperature of Zone 1 is hotter
than the outside temperature at certain hours of the day. It is also
above thermal comfort for most of the day.
Zone Settings - HVAC - Mixed System
Once the temperature goes above the set range, the AC kicks in and
cools the interior.
Hourly Temperature Profile

of 16
The graph shows that the largest amount of heat gain is due to
direct solar. Adding shading devices will help reduce this.
When the HVAC system is activated, the largest amount of hourly
gains is due to the system. As before, adding shading devices could
help reduce the amount the system needs to be used.
Hourly Heat Gains/Losses

of 16
Window Material - Single Glazed
The text data shows that the total heat gain due to the HVAC is
22399.45 Btu.
Window Material - Double Glazed Low E
By switching to double glazed, low-E windows, the total heat gain
due to the HVAC is 18440.38 Btu. This is a reduction of over 17%.
Hourly Heat Gains/Losses

of 16
This chart will show you the number of hours and percentage of
time that the zone is in the bounds of the comfort temperature
range with just natural ventilation. Shown here, the temperature is
only comfortable 1/3 of the time. The other 2/3 it would need to be
heated or cooled.
Be sure your hours of operation are set, otherwise the results will
be skewed.
Climate: San Francisco
If the building were located in San Francisco instead of New York,
there would be about the same number of hours in the comfort zone.
Temperature Distribution

of 16
South Facade - Brick
This graph shows the amount of heat gain strictly from solar for
each hour, averaged monthly.
South Facade - Single Glazed
Allowing the south facade to be glazed creates a significant increase
in solar gain.
Direct Solar Gains

of 16
Another way to view the amount of comfort hours for a zone is
through this calculation. Make sure your zones are set to none or
natural ventilation.
If your zone is set to an HVAC system, you can view the amount of
heating or cooling needed per month for that zone. The top chart
shows when the thermostat is set to 78 max. The bottom is at 82
max, thus reducing the cooling load.
Monthly Loads/Discomfort

Notes:
page 16 of 16
Passive Gains Breakdown
This analysis will show you
the areas of biggest concern
for gains/losses in your
building.
Here you can see that
heat loss through the
external fabric is the largest
contributor.

Thermal Analysis in Ecotect

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