About CalGreen

What is CalGreen?

CalGreen (the California Green Building Standards Code, Title 24, Part 11) is California's statewide green building code. On August 2, 2023, California became the first state in the country to make embodied carbon emission control a mandatory part of the building code. The embodied carbon provisions took effect July 1, 2024, and are the part of CalGreen most relevant to structural engineers.

Who has to comply

As of July 1, 2024, all commercial projects 100,000 sf and larger, and schools 50,000 sf and larger are required to comply with the embodied carbon measures. Note the threshold change that affects more projects going forward: on January 1, 2026 the square footage threshold dropped to 50,000 square feet for all covered projects. That brings a much larger share of K-12 and commercial work into scope, so smaller projects that were previously exempt may now trigger the requirements.

The three compliance pathways

CalGreen offers three routes, and a project picks one:

• Building reuse. This pathway applies to projects renovating existing buildings and requires reusing at least 45% of the existing building's primary structural elements and enclosure. Because structural elements are central to this calculation, the structural engineer is directly involved in demonstrating what qualifies.

• Whole Building Life Cycle Assessment (WBLCA). This pathway involves conducting a whole building life-cycle assessment to demonstrate a 10% reduction in embodied carbon compared to a baseline model. The structural system is usually the largest single contributor to the model, so structural choices drive whether the reduction target is met.

• Prescriptive (EPD) pathway. This route requires specifying structural, envelope, and insulation materials with global warming potential (GWP) values below the limits listed in the CALGreen requirements table, documenting those values through Environmental Product Declarations (EPDs), and signing an attestation of compliance.

What structural engineers need to be aware of

The structural scope drives most of the embodied carbon outcome. Concrete, steel, and other structural materials make up the bulk of a building's embodied carbon, so the structural engineer's decisions largely determine whether a project clears the WBLCA reduction or the prescriptive GWP limits.

EPDs become part of the deliverable. Under the prescriptive pathway, you'll need to specify materials whose EPDs show GWP below the code thresholds and collect those EPDs as compliance documentation. This affects specifications and submittal review, not just design. Window assemblies and insulation are excluded from certain calculations, but structural materials are central.

Coordinate the pathway choice early. The three pathways place very different demands on the structural design and documentation. Deciding which one applies at the start - ideally with the architect and owner - avoids rework, since switching pathways late can mean redoing material specifications or running an LCA that wasn't planned for.

Watch the 2026 threshold. With the trigger now at 50,000 sf, projects that didn't previously require embodied carbon documentation may now fall under the code. Confirm scope early in any new commercial or school project near or above that size.

Documentation and forms. Compliance is typically shown through worksheets and signed declarations - for example, GWP tables with EPD values, the prescriptive attestation, or supporting forms the enforcing agency may request. Confirm the current forms and any local amendments with the authority having jurisdiction, since enforcement details can vary.