California Green Building Standards Code (CALGreen)

The California Green Building Standards Code, known as CALGreen, is Part 11 of the California Building Standards Code (Title 24, California Code of Regulations). It was the first statewide mandatory green building code in the United States and sets requirements for water efficiency, construction waste diversion, indoor air quality, material conservation, EV charging readiness, and embodied carbon. Unlike most Title 24 parts, CALGreen is a California-original code rather than an amended model code.

The 2025 CALGreen is the current edition, effective January 1, 2026, replacing the 2022 edition. CALGreen applies a baseline of mandatory measures to nearly every project, plus voluntary Tier 1 and Tier 2 levels that cities can adopt or that owners can pursue for green certification. Because local jurisdictions may adopt the tiers and add amendments, your exact obligations depend on the edition and reach amendments your city or county adopted — which is exactly what GoCodebook reconciles for you.

CALGreen is split into residential mandatory measures and nonresidential mandatory measures, organized around five themes: planning and design, energy efficiency, water efficiency and conservation, material conservation and resource efficiency, and environmental quality (indoor air). Every covered project must meet the mandatory baseline. The most cited mandatory items include recycling or salvaging at least 65% of construction and demolition waste, water-conserving fixtures, and low-emitting (low-VOC) finishes and materials.

On top of the baseline, CALGreen defines voluntary Tier 1 and Tier 2 levels in its appendices for projects that want to go further (and that some jurisdictions adopt as mandatory). To reach a tier, a project must meet all mandatory measures plus the additional Tier 1 or Tier 2 prerequisites and electives. Energy-efficiency targets in CALGreen coordinate with the California Energy Code (Part 6).

EV charging requirements were substantially restructured in the 2025 CALGreen. Multifamily projects now generally require one EV-ready receptacle per dwelling unit, a shift away from the older percentage-of-parking approach, and nonresidential and Tier 2 projects see higher shares of EV-capable spaces and installed charging stations (EVCS). Water efficiency measures cover low-flow fixtures, irrigation controls, and separate indoor/outdoor water meters for larger buildings.

Construction waste diversion requires recycling or salvaging at least 65% of nonhazardous construction and demolition debris, documented with a waste-management plan. These provisions interact with the California Building Code (CBC, Part 2) for the underlying construction and are checked at permit and inspection. See where coverage is deepest.

The biggest change in the 2025 cycle is embodied carbon. CALGreen now requires larger nonresidential projects to reduce the carbon embedded in their building materials through one of several pathways — a whole-building life-cycle assessment (LCA), a prescriptive material-reuse path, or environmental product declarations (EPDs) for key materials like concrete and steel. As of January 1, 2026, the threshold for nonresidential buildings dropped to roughly 50,000 square feet, pulling many more projects into compliance.

Embodied carbon is new enough that teams frequently misjudge which pathway applies and when documentation is due. You can ask GoCodebook which embodied-carbon path fits your project, or check how CALGreen interacts with the California Energy Code (Part 6) on operational efficiency. GoCodebook returns the governing CALGreen section with a citation so you can verify the original language.

California's adopted codes — including the California Green Building Standards Code (CALGreen) — are published under Title 24 and hosted on code libraries such as UpCodes (up.codes) and ICC Digital Codes from the International Code Council (ICC). Those let you read the text section by section.

GoCodebook goes further: instead of searching a code library, you ask a question and get the controlling provision for the edition and local amendments your jurisdiction adopted, with a citation to verify. See how GoCodebook compares to UpCodes and ICC.