## NA6.2 Default U-factor

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 NA6-5

C2 = Coefficient selected from Table NA6-5

UC = Center of glass U-factor calculated in accordance with NFRC 100 Section 4.5.3.1 www.nfrc.org/software.aspx

#### Table NA6-5 – U-factor Coefficients

Product Type | Frame Type | C1 | C2
Site-Built Vertical Fenestration | Metal | 0.311 | 0.872
Metal Thermal Break | 0.202 | 0.867
Non-Metal | 0.202 | 0.867
Skylights with a Curb | Metal | 0.711 | 1.065
Metal Thermal Break | 0.437 | 1.229
Non-Metal | 0.437 | 1.229
Skylights with no Curb | Metal | 0.195 | 0.882
Metal Thermal Break | 0.310 | 0.878
Non-Metal | 0.310 | 0.878