ASHRAE-90.1-2022- - Page 030
Extracted Content
skylight effective aperture: the overall amount of visible transmittance of the roof via skylights . Skylight effective aperture is calculated according to the following formula:
Sidelighting Effective Aperture
0.85 Skylight Area Skylight VT WF
= -------------------------------------------------------------------------------------------------- - Daylight Area Under Skylights
where Skylight Area = total fenestration area of skylights Skylight VT = area-weighted average visible transmittance of skylights as determined in accordance with Section 5.8.2.6. WF = area-weighted average skylight well factor, where skylight well factor is 0.9 if skylight well depth is less than 2 ft, or 0.7 if skylight well depth is 2 ft or greater. Skylight well depth is measured vertically from the underside of the lowest point on the skylight glazing to the ceiling plane under the skylight .
skylight well: the shaft from the skylight to the ceiling.
slab-on-grade floor: that portion of a slab floor of the building envelope that is in contact with the ground and that is either above grade or is less than or equal to 24 in. below the final elevation of the nearest exterior grade .
heated slab-on-grade floor: a slab-on-grade floor with a heating source either within or below it. unheated slab-on-grade floor: a slab-on-grade floor that is not a heated slab-on-grade floor .
small electric motor: a NEMA general purpose, alternating current, single-speed induction motor, built in a two-digit frame number series in accordance with NEMA Standards Publication MG1-1987, including IEC metric equivalent motors; constructed in the NEMA 42, 48, and 56 frame sizes or IEC metric equivalent.
solar energy source: source of thermal, chemical, or electrical energy derived from direct conversion of incident solar radiation at the building site .
solar heat gain coefficient (SHGC): the ratio of the solar heat gain entering the space through the fenestra- tion area to the incident solar radiation. Solar heat gain includes directly transmitted solar heat and absorbed solar radiation, which is then reradiated, conducted, or convected into the space . (See fenestration area .)
south-oriented: facing within 45 degrees of true south in the northern hemisphere; facing within 45 degrees of true north in the southern hemisphere.
space: an enclosed space within a building . The classifications of spaces are as follows for the purpose of determining building envelope requirements:
conditioned space: a cooled space, heated space, or indirectly conditioned space defined as follows:
a. cooled space: an enclosed space within a building that is cooled by a cooling system whose sensible
output capacity is 3.4 Btu/h·ft [2] of floor area. b. heated space: an enclosed space within a building that is heated by a heating system whose output
capacity relative to the floor area is greater than or equal to the criteria in Table 3.2. c. indirectly conditioned space: an enclosed space within a building that is not a heated space or a
cooled space, which is heated or cooled indirectly by being connected to adjacent spaces, provided
- the product of the U-factors and surface areas of the space adjacent to connected spaces exceeds the combined sum of the product of the U-factor s and surface areas of the space adjoining the outdoors, unconditioned spaces, and to or from semiheated spaces (e.g., corridors) or
- that air from heated or cooled spaces is intentionally transferred (naturally or mechanically) into the space at a rate exceeding 3 ach (e.g., atria). semiheated space: an enclosed space within a building that is heated by a heating system whose output capacity is greater than or equal to 3.4 Btu/h·ft [2] of floor area but is not a conditioned space . unconditioned space: an enclosed space within a building that is not a conditioned space or a semi- heated space . Crawlspaces, attics, and parking garages with natural or mechanical ventilation are not considered enclosed spaces .
space conditioning category:
a. nonresidential conditioned space (See nonresidential .) b. residential conditioned space (See residential .) c. nonresidential and residential semiheated space (See space .)
28 ANSI/ASHRAE/IES Standard 90.1-2022 (I-P)