Marin County, CA Building Safety: Green Building Code (2026)

Under Section 19.04.110, the Marin County Board of Supervisors adopted local amendments to California Green Building Standards Code (CALGreen) Chapters 3, 4, and 5, finding them reasonably necessary under Health and Safety Code Sections 17958.7 and 18941.5 because of Marin's exposure to flooding and sea-level rise, wildfire, and seismic activity. The chapter's stated purposes, listed in Section 19.04.110, include increasing energy efficiency, reducing fossil fuel use, encouraging water and resource conservation, cutting construction waste, improving indoor air quality, and encouraging all-electric buildings, while requiring covered projects to meet all mandatory measures of the 2025 CALGreen Code (Title 24, Part 11) and 2025 California Energy Code (Title 24, Part 6).

Covered projects, defined in Section 19.04.110 as additions or alterations to existing single-family, multifamily, hotel/motel, or nonresidential buildings needing a building permit, must meet compliance thresholds set out in the Table 1 standards of Section 19.04.140, which vary by project type and size and include CALGreen Tier 1 measures plus electric-vehicle infrastructure requirements. Section 19.04.135 further amends CALGreen so that, when a project's electrical service panel is modified, the panel and any on-site transformers must have enough capacity to simultaneously charge twenty percent of on-site parking spaces at Level 2 EV-Ready. The chapter also exempts temporary buildings such as construction trailers, unconditioned space, and buildings on a historic register from these requirements, and lets an applicant request a hardship or infeasibility exemption from the chief building official, appealable in writing if denied.