Equation NA6-1
UT= C1 + (C2 X Uc)
Where:
UT = U-factor Is the Total Performance of the fenestration including glass and frame
C1 = Coefficient selected from Table NA6-6
C2 = Coefficient selected from Table NA6-6
UC = Center of glass U-factor calculated in accordance with NFRC 100 Section 4.5.3.1 (http://www.nfrc.org/software.aspx)
Table NA6-6 – U-factor Coefficients
|
Product Type |
Frame Type |
C1 |
C2 |
|
Metal |
0.311 |
0.872 | |
|
Site-Built Vertical Fenestration |
Metal Thermal Break |
0.202 |
0.867 |
|
Site-Built Vertical Fenestration |
Non-Metal |
0.202 |
0.867 |
|
Skylights with a Curb |
Metal |
0.711 |
1.065 |
|
Skylights with a Curb |
Metal Thermal Break |
0.437 |
1.229 |
|
Skylights with a Curb |
Non-Metal |
0.437 |
1.229 |
|
Skylights with no
Curb |
Metal |
0.310 |
0.878 |
|
Skylights with no
Curb |
Metal Thermal Break |
0.195 |
0.882 |
|
Skylights with no
Curb |
Non-Metal |
0.310 |
0.878 |