U-factor and SHGC.
For vertical fenestration, the maximum U-factor and solar heat gain coefficient (SHGC) shall be as specified in Table C402.3, based on the window projection factor. For skylights, the maximum U-factor and solar heat gain coefficient (SHGC) shall be as specified in Table C402.3.
|PF = A/B||(Equation C4-2)|
|PF||=||Projection factor (decimal).|
|A||=||Distance measured horizontally from the furthest continuous extremity of any overhang, eave, or permanently attached shading device to the vertical surface of the glazing.|
|B||=||Distance measured vertically from the bottom of the glazing to the underside of the overhang, eave, or permanently attached shading device.|
Where the fenestration projection factor for a specific vertical fenestration product is greater than or equal to 0.2, the required maximum SHGC from Table C402.3 shall be adjusted by multiplying the required maximum SHGC by the multiplier specified in Table C402.3.3.1 corresponding with the orientation of the fenestration product and the projection factor.
SHGC ADJUSTMENT MULTIPLIERS
|PROJECTION FACTOR||ORIENTED WITHIN 45 |
DEGREES OF TRUE NORTH
|ALL OTHER |
|0.2 ≤ PF < 0.5||1.1||1.2|
|PF ≥ 0.5||1.2||1.6|
For compliance with Section C402.3.3, the SHGC for dynamic glazing shall be determined using the manufacturer's lowest-rated SHGC, and the VT/SHGC ratio shall be determined using the maximum VT and maximum SHGC. Dynamic glazing shall be considered separately from other fenestration, and area-weighted averaging with other fenestration that is not dynamic glazing shall not be permitted.