ASHRAE-90.1-2022- - Page 291

Extracted Content

modeled with a solar reflectance and thermal emittance as required in Section 5.5.3.2.2 and Section 5.5.3.2.2(a). All other above-grade walls, including those exempt from the requirements in Section 5.5.3.2.2, shall be modeled the same as the proposed design . d. Fenestration shall be assumed to be flush with the wall or roof . Fenestration U-factor and SHGC shall

be the maximum allowed for the appropriate class of construction, space conditioning category, and climate zone in accordance with Section 5.5.4. Where there is no SHGC requirement, the SHGC shall be equal to 0.40 for all vertical fenestration and 0.55 for skylights . The VT for fenestration in the base envelope design shall be equal to 1.10 times the SHGC . The fenestration area for new buildings or additions shall be modeled the same as the proposed building unless the following apply:

1. Where the fenestration area exceeds the maximum allowed by Section 5.5.4.2, the area shall be reduced proportionally along each exposure until the limit set in Section 5.5.4.2 is met.
2. Where the fenestration area facing west or east of the proposed design exceeds the area limit set in Section 5.5.4.5, the baseline building performance shall be generated by simulating the building with its actual orientation and again after rotating the entire building 90, 180, and 270 degrees and averaging the results of the four simulations.
3. Where the Normative Appendix C calculation is being used to determine energy credits in accordance with Section 11.5.2.1, for building use types included in Table G3.1.1-1 where the proposed fenestration area is less than the value in Table G3.1.1-1, vertical fenestration areas shall equal that in Table G3.1.1-1 based on the area of gross above-grade walls that separate conditioned spaces and semiheated spaces from the exterior. Follow additional fenestration modeling requirements for base- line building performance in Table G3.1. e. Manually operated interior shades shall be modeled on all vertical fenestration as described in Section

C3.5.5.1. Permanent shading devices, such as fins and overhangs, shall not be modeled. f. Daylight areas and photosensor locations shall be modeled as described in Section C3.5.3 after reducing the fenestration area as described in Section C3.6(d). g. The air leakage rate of the building envelope ( I75Pa ) at a fixed building pressure differential of 75 Pa

(0.30 in. of water) shall be 0.35 cfm/ft [2] and shall be converted to units for the energy model using the same method as the proposed envelope performance factor .

ANSI/ASHRAE/IES Standard 90.1-2022 (I-P) 289