A5.106.11 Heat Island Effect
Use one or a combination of strategies 1 and 2 for 50 percent of site hardscape or put 50 percent of parking underground.
Use roofing materials having a minimum aged solar reflectance and thermal emittance complying with Sections A184.108.40.206.1 and A220.127.116.11.2 or a minimum aged Solar Reflectance Index (SRI) complying with Section A18.104.22.168.3 and as shown in Table A22.214.171.124.2 for Tier 1 or Table A126.96.36.199.3 for Tier 2.
- Roof constructions that have a thermal mass over the roof membrane, including areas of vegetated (green) roofs, weighing at least 25 pounds per square foot.
- Roof area covered by building integrated solar photovoltaic and building integrated solar thermal panels.
If Cool Roof Rating Council (CRRC) testing for aged reflectance is not available for any roofing products, the aged value shall be determined using the CRRC certified initial value using the equation ρaged = [0.2 + β [ρinitial — 0.2], where ρinitial = the initial solar reflectance and soiling resistance, β, listed by product type in Table A188.8.131.52.1.
VALUES OF SOILING RESISTANCE, β, BY PRODUCT TYPE
|PRODUCT TYPE||CRRC PRODUCT CATEGORY||β|
|Field-applied coating||Field-applied coating||0.65|
|Other||Not a field-applied coating||0.70|
Roofing materials shall have a CRRC initial or aged thermal emittance as determined in accordance with ASTM E408 or C1371 equal to or greater than those specified in Table A184.108.40.206.2 for Tier 1 and Table A220.127.116.11.3 for Tier 2.
Solar Reflectance Index (SRI) equal to or greater than the values specified in Table A18.104.22.168.2 for Tier 1 and Table A22.214.171.124.3 for Tier 2 may be used as an alternative to compliance with the aged solar reflectance values and thermal emittance.
SRI values used to comply with this section shall be calculated using the Solar Reflectance Index (SRI) Calculation Worksheet (SRI-WS) developed by the California Energy Commission or in compliance with ASTM E1980-11 as specified in the California Energy Code, Section 110.8(i)3. Solar reflectance values used in the SRI-WS shall be based on the aged reflectance value of the roofing product or the equation in section A126.96.36.199.1 if the CRRC certified aged solar reflectance are not available. Certified Thermal emittance used in the SRI-WS may be either the initial value or the aged value listed by the CRRC.
Note: The Solar Reflectance Index Calculation Worksheet (SRI-WS) is available by contacting the Energy Standard Hotline at 1-800-772-3300, website at www.energy.ca.gov or by email at Title24@energy.state.ca.us.