Many federal, state and local government entities now include cool roofs in their building codes, green building standards and energy efficiency programs. However, requirements for cool roofs differ by national or state climate zone in some cases so be sure to refer to the California and U.S. climate zone maps below to understand the requirements in your area.
California has 16 climate zones for the purposes of state codes and standards (source: LBNL-Heat Island Group )
In California, all new or replacement low-slope roofs are required by the building energy efficiency standards (Title 24) to be cool roofs, as are steep-slope roofs in several California climate zones.
The Cool Roof Rating Council (CRRC) is an independent, non-profit organization that maintains a third-party rating program, which rates and publishes a roof product’s radiative properties (solar reflectance and thermal emittance). Once a product is rated, the results are published on their online Rated Products Directory, which is a great resource to check to see whether roofing products comply with Title 24 or other codes and standards.
CRRC tests products when they are both new and aged. Aged products are weathered outside for three years. The weathered rating will indicate how the roof products’ radiative properties change when exposed to sun, soil, wind, rain and other natural elements. Many building codes and utility rebates specify the weathered rating because some products become less reflective over time, thus become less effective at conserving energy.
See below for more on these building codes, green building standards and energy efficiency programs that currently include cool roof provisions, broken down by roof slope.
Note: Title 24 requirements for the 2013 standard will go into effect in 2014.
Download and view the below table by clicking here.
Keep in mind that these requirements are only the minimum criteria for compliance; many California cities have gone above and beyond to exceed these requirements in their local planning efforts – see what local initiatives some California cities are undertaking.
And to find products that meet the required minimum values for solar reflectance, thermal emittance, and solar reflectance index (listed in the table above), you can browse the Cool Roof Rating Council’s Rated Products Directory.