California alters building code to reduce embodied carbon in building construction

Construction activity causes about 40% of California’s greenhouse gas pollution

The state of California in the US has changed its building code to limit the amount of embodied carbon emissions allowed in commercial and school buildings.

The California Building Standards Commission (CBSC) voted the changes to two building codes into effect, making it the first State in the US to implement required embodied carbon reduction in some buildings.

The new code will “limit embodied carbon emissions in the construction, remodel, or adaptive reuse of commercial buildings larger than 100,000 square feet (9,230 square metre) and school projects over 50,000 square feet (4,650 square metre),” according to The American Institute of Architects (AIA) California, which worked closely with policy-makers on the changes.

The new changes will come into effect July 1, 2024. The change is an amendment to the 2022 California Green Building Standards Code (CALGreen), California’s first statewide green building code, which was first developed to supplement the general code in 2007.

Embodied carbon encapsulates the carbon emissions generated from the entire lifespan of a building, including manufacturing, construction, maintenance and eventual demolition.

“This action is a real catalyst for change that will push the industry forward in rapidly addressing the growing climate emergency,” said William Leddy, AIA California Vice President of Climate Action.

In the state of California – the world’s fifth largest economy – construction activity is credited with about 40% of the state’s greenhouse gas pollution. By reducing embodied carbon, California aims to mitigate its contribution to climate change and promote sustainable building practices.

The compliance options include reusing at least 45% of an existing structure, using materials that meet specific emission limits, and using a performance-based approach that involves analysing the entire lifecycle of a building.

“The most sustainable buildings are the ones that are already built. Prioritizing the reuse of existing buildings not only accelerates the reduction of embodied carbon emissions from new construction, it ‘incentivises’ the industry to address California’s severe housing crisis more quickly and efficiently, creating more sustainable and resilient communities,” added Leddy.