California Title 24 Cool Roof Requirements

California's Building Energy Efficiency Standards, published as Title 24, Part 6 of the California Code of Regulations, form the state's Energy Code. They are developed and maintained by the California Energy Commission (CEC) and updated on a three-year cycle. The 2025 standards take effect on 1 January 2026. A companion part, CALGreen (Title 24, Part 11), contains green building provisions, some of them voluntary.

California was one of the first jurisdictions to build "cool roof" provisions into a statewide energy code, and its rules have influenced other codes and local ordinances.

What the cool roof provisions do

The Energy Code sets minimum values for a roof's aged solar reflectance and thermal emittance, or a combined Solar Reflectance Index, in many situations. Requirements vary by:

• building type (nonresidential, high-rise residential, low-rise residential)
• roof slope (low-slope and steep-slope have different thresholds)
• climate zone – California is divided into 16 building climate zones, and cool roof rules are strongest in the hotter inland zones

The provisions apply to new construction and, in many cases, to reroofing projects that replace a large share of an existing roof. Trade-offs are allowed: for example, extra insulation or other efficiency measures can sometimes offset a roof that does not meet the reflectance values, using the performance compliance path.

Rated products

Roofing products used to comply must have their radiative properties rated by the Cool Roof Rating Council. Contractors and inspectors check the CRRC label or directory listing for the product's aged reflectance and emittance.

Why it matters for roofers

In California, choosing a roof colour or coating can be a code issue, not only a design choice. Dark shingles or membranes that do not meet the applicable values may require compliance trade-offs on the energy documentation. Reroofing permits often require a cool roof compliance form.

Wider influence

Cool roof provisions now appear in other energy standards, notably ASHRAE 90.1, which added solar reflectance and thermal emittance requirements in its 2010 edition, and in local ordinances in cities across the United States.