This chapter covers the requirements for efficiency features used for the building envelope of nonresidential, hotel and motel occupancy building types. Building energy use is affected by heating and cooling loads.
- Heating loads are affected by infiltration and conduction losses through building envelope components, including walls, roofs, floors, slabs, windows, and doors.
- Cooling loads are dominated by solar gains through windows and skylights, internal gains due to lighting, plug loads, and occupant use, and from additional ventilation loads needed for indoor air quality.
The 2022 Building Energy Efficiency Standards (Energy Code) include several important changes to the building envelope component requirements as described below:
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Steep-sloped cool roof prescriptive requirements were increased from a solar reflectance of 0.20 and thermal emittance of 0.75 to solar reflectance of 0.25 and thermal emittance of 0.85 in Climate Zones 2 and 4 through 16.
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Added a new prescriptive requirement for continuous above roof deck insulation for roof alterations. For roof replacements the requirement is R-23 in Climate Zones 1 through 5 and 9 through 16, and R-17 in Climate Zones 6 through 8. For roof recovers, the requirement calls for a minimum R-10 insulation be added or to meet the insulation requirements for roof replacements, whichever is less.
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Prescriptive fenestration requirements (U-factor and RSHGC) now vary by climate zone, but visible transmittance (VT) remains the same. For fixed windows, the U-factor and RSHGC requirements were reduced in Climate Zones 9 and 11 through 15. For curtain wall and storefront windows, the U-factor and RSHGC requirements were reduced in Climate Zones 1 and 7.
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Revised the RSHGC equation (Equation 140.3-A) to provide credit for exterior horizontal slats, in addition to overhangs.
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Reduced the prescriptive U-factor requirement for metal framed walls equivalent to an additional R-2 continuous insulation.