Revit uses the Solar Heat Gain Coefficient (SHGC) for the thermal properties of window and door glazing.
SHGC measures how well a window blocks heat from sunlight. It is the fraction of the heat from the sun that enters through a window. SHGC is expressed as a number between 0 and 1. The lower the SHGC of a window, the less solar heat it transmits. The solar-optical properties, including the SHGC value, of glazings depend on the incident angle of the radiation passing through the glazing.
The following table is an excerpt from Table 31 in the 2005 ASHRAE Handbook of Fundamentals. The source table contains a tabular listing of 75+ different types of glazings along with their incidence angular-dependent SHGC values.
| Glazing System | Incidence Angles | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| ID | Glass, Thick., in. | Center Glazing  |
Normal 0.00 | 40.00 | 50.00 | 60.00 | 70.00 | 80.00 | Hemis., Diffuse | ||
| Uncoated Single Glazing | |||||||||||
| 1a | 1/8 | CLR | 0.90 | SHGC | 0.86 | 0.84 | 0.82 | 0.78 | 0.67 | 0.42 | 0.78 |
|
0.83 | 0.82 | 0.80 | 0.75 | 0.64 | 0.39 | 0.75 | ||||
|
0.08 | 0.08 | 0.10 | 0.14 | 0.25 | 0.51 | 0.14 | ||||
|
0.08 | 0.08 | 0.10 | 0.14 | 0.25 | 0.51 | 0.14 | ||||
|
0.09 | 0.10 | 0.10 | 0.11 | 0.11 | 0.11 | 0.10 | ||||
| 1b | 1/4 | CLR | 0.88 | SHGC | 0.81 | 0.80 | 0.78 | 0.73 | 0.62 | 0.39 | 0.73 |
|
|
0.88 | 0.87 | 0.85 | 0.80 | 0.69 | 0.43 | 0.80 | ||||
|
|
0.08 | 0.09 | 0.11 | 0.15 | 0.27 | 0.53 | 0.14 | ||||
|
|
0.08 | 0.09 | 0.11 | 0.15 | 0.27 | 0.53 | 0.14 | ||||
|
|
0.16 | 0.17 | 0.18 | 0.19 | 0.19 | 0.17 | 0.17 | ||||
| 1c | 1/4 | BRZ | 0.68 | SHGC | 0.73 | 0.71 | 0.68 | 0.64 | 0.55 | 0.34 | 0.65 |
|
|
0.65 | 0.62 | 0.59 | 0.55 | 0.46 | 0.27 | 0.56 | ||||
|
|
0.06 | 0.07 | 0.08 | 0.12 | 0.22 | 0.45 | 0.12 | ||||
|
|
0.06 | 0.07 | 0.08 | 0.12 | 0.22 | 0.45 | 0.12 | ||||
|
|
0.29 | 0.31 | 0.32 | 0.33 | 0.33 | 0.29 | 0.31 | ||||
U-Values are also associated with glazings for purposes of calculating conduction values for cooling and heating.