As the 2022 Energy Code update moves closer to its January 1, 2023 start date, we’re seeing more firms designing to the new code and needing to know what will be required. We recently outlined the new requirements for PVs and batteries for non-residential construction. Here we touch on the small but important shifts in requirements for non-residential roofing. Specifically, there are updates to solar reflectance, emissivity and air barriers.
Solar Reflectance (SR) or albedo, is the percentage of solar energy reflected by a surface. In the code, the scale is 0 – 1, where 0 is a black surface and 1.0 is a white surface. In all but two California climate zones (CZ 1 and 3), prescriptive SR for steep roofs will increase (lighter color), from 0.20 to 0.25. Low-sloped roofs (less than 2:12) won’t change in the new code, but are still required to have a higher SR at 0.63 across all climate zones.
Emissivity is the effectiveness of a material in emitting energy as thermal radiation. Again, the scale is 0 – 1, where higher numbers indicate more ability to shed heat. Prescriptively, emissivity for steep-sloped roofs will increase from 0.75 to 0.80 for all California climate zones except CZ 1 and 3. Low-sloped roofs will remain at 0.75.
Note that you’ll also see data on Solar Reflective Index, or SRI. SRI is calculated using solar reflectance and emissivity together and uses a scale of 1 – 100. In the code, you can use either SRI alone, or emissivity and solar reflectance together. For steep-sloped roofs, other than CZ 1 and 3, the SRI increased from 16 to 23. Low-sloped roofs SRI will remain at 75.
Air Barriers, which are applicable to the whole building, will now be required in all California climate zones. Previously they were only required in climate zones 10-16.
The main take-away here is that the California Energy Commissioning is responding to increasing temperatures across California by requiring lighter-colored roofs that reflect the sun and keep buildings cooler inside, which reduces energy demand and, ultimately, carbon emissions.
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