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NA6.4 Default Visible Transmittance, VT

Equation NA6-3 - VT of Center of Glass (COG) calculation

VTT = VTF x VTC

Where:

VTT = Is the Total Performance of the fenestration including glass and frame

VTF = 0.53 for projecting windows, such as casement and awning windows

VTF = 0.67 for operable or sliding windows

VTF = 0.77 for fixed or non-operable windows

VTF= 0.88 for curtain wall/storefront, Site-built and manufactured non-curb mounted skylights

VTF = 1.0 for Curb Mounted manufactured Skylights

VTC = Center of glass VT is calculated in accordance with NFRC 200 Section 4.5.1.1 or NFRC 202 for Translucent Products or NFRC 203 for Tubular Daylighting Devices and Hybrid Tubular Daylighting Devices or ASTM E972 (http://www.nfrc.org/software.aspx)

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