ASHRAE-90.1-2022- - Page 062

Extracted Content

When this exception is used, separate calculations shall be performed for these sections of the building envelope, and these values shall not be averaged with any others for compliance purposes. No credit shall be given here or elsewhere in the building for not fully utilizing the fenestration area allowed. 4. For dynamic glazing, the minimum SHGC shall be used to demonstrate compliance with this section. Dynamic glazing shall be considered separately from other vertical fenestration, and areaweighted averaging with other vertical fenestration that is not dynamic glazing shall not be permitted.

5.5.4.4.2 SHGC of Skylights. Skylights shall have an SHGC not greater than that specified in Tables 5.5-0 through 5.5-8. Exceptions to 5.5.4.4.2:

1. Skylights are exempt from SHGC requirements provided the following: a. They have a glazing material or diffuser with a measured haze value greater than 90% when

tested according to ASTM D1003. b. They have a skylight VT greater than 0.40. c. They have all general lighting in the daylight area under skylights controlled by multilevel

photocontrols in accordance with Section 9.4.1.1(f). 2. For dynamic glazing, the minimum SHGC shall be used to demonstrate compliance with this section. Dynamic glazing shall be considered separately from other skylights, and areaweighted averaging with other skylights that is not dynamic glazing shall not be permitted.

5.5.4.5 Fenestration Orientation. T h e vertical fenestration shall comply with either (a) or (b):

a. For Climate Zones 0 through 8:

AW  ( AT )/4 and AE  ( AT )/4

b. For Climate Zones 0 through 3,

AW × SHGCW  ( AT × SHGCC )/4 and AE × SHGCE  ( AT × SHGCC )/4

where AW = west-oriented vertical fenestration area AE = east-oriented vertical fenestration area AT = total vertical fenestration area SHGCC = SHGC criteria in Tables 5.5-0 through 5.5-8 for each climate zone SHGCE = SHGC for east-oriented fenestration that complies with Section 5.5.4.4.1 SHGCW = SHGC for west-oriented fenestration that complies with Section 5.5.4.4.1

Exceptions to 5.5.4.5:

2. Buildings with shade on 75% of the east- and west-oriented vertical fenestration areas from permanent projections, existing buildings, existing permanent infrastructure, or topography at 9 a.m. and 3 p.m., respectively, on the summer solstice (June 21 in the northern hemisphere).

3. Alterations and additions with no increase in vertical fenestration area .

4. Buildings in Climate Zone 8.

Exceptions to 5.5.4.6:

1. A light-to-solar-gain ratio ( LSG ) of not less than 1.25 is allowed to be used as an alternative to VT / SHGC . When using this option, the center-of-glass VT and the center-of-glass SHGC shall be deter

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