ASHRAE-90.1-2022- - Page 061
Extracted Content
Table 5.5.4.4.1 SHGC Multipliers for Permanent Projections
| Projection Factor (PF) | SHGC Multiplier (South, East, and West Orientations) |
|---|---|
| 0 to 0.10 | 1.00 |
| >0.10 to 0.20 | 0.91 |
| >0.20 to 0.30 | 0.82 |
| >0.30 to 0.40 | 0.74 |
| >0.40 to 0.50 | 0.67 |
| >0.50 to 0.60 | 0.61 |
| >0.60 to 0.70 | 0.56 |
| >0.70 to 0.80 | 0.51 |
| >0.80 to 0.90 | 0.47 |
| >0.90 to 1.00 | 0.44 |
5.5.4.3 Fenestration U-Factor. Fenestration shall have a U-factor not greater than that specified in Tables 5.5-0 through 5.5-8.
Exception to 5.5.4.3: The U-factor for skylights is permitted to be increased to no greater than 0.90 Btu/
h·ft [2] ·°F in Climate Zones 0 through 3 and 0.75 Btu/h·ft [2] ·°F in Climate Zones 4 through 8, provided the skylights meet all of the criteria in Section 5.5.4.4.2, Exception 1.
5.5.4.4 Fenestration Solar Heat Gain Coefficient (SHGC) 5.5.4.4.1 SHGC of Vertical Fenestration. Vertical fenestration shall have an SHGC not greater than that specified in Tables 5.5-0 through 5.5-8.
Exceptions to 5.5.4.4.1:
- For demonstrating compliance for south -, east -, or west-oriented vertical fenestration shaded by opaque permanent projections that will last as long as the building itself, the SHGC of the shaded vertical fenestration in the proposed design is permitted to be reduced by using the multipliers in Table 5.5.4.4.1. Permanent projections consisting of open louvers shall be considered to provide shading, provided that no sun penetrates the louvers during the peak sun angle on June 21.
- For demonstrating compliance for south -, east -, or west-oriented vertical fenestration shaded by partially opaque permanent projections (e.g., framing with glass or perforated metal) that will last as long as the building itself, the projection factor ( PF ) shall be reduced by multiplying it by a factor of Os, which is derived as follows:
Os = ( Ai × Oi ) + ( Af × Of )
where Os = percent opacity of the shading device Ai = percent of the area of the shading device that is a partially opaque infill Oi = percent opacity of the infill for glass Oi = (100% – Ts ), where Ts is the solar transmittance as determined in accordance with NFRC 300; for perforated or decorative metal panels, Oi = percentage of solid material Af = percent of the area of the shading device that represents the framing members Of = percent opacity of the framing members; if solid then 100%
The SHGC of the shaded vertical fenestration in the proposed building is permitted to then be reduced by using the multipliers in Table 5.5.4.4.1 for each fenestration product. 3. Vertical fenestration that is located on the street side of the street-level story only, provided that a. the street side of the street-level story does not exceed 20 ft in height, b. the fenestration has a continuous overhang with a weighted average PF greater than 0.5, and c. the fenestration area for the street side of the street-level story is less than 75% of the gross
wall area for the street side of the street-level story .
ANSI/ASHRAE/IES Standard 90.1-2022 (I-P) 59