California is now the first state in the country to formally implement general code requirements for reducing embodied carbon in the built environment.

On Wednesday, August 2, the California Building Standards Commission (CBSC) voted unanimously to approve two amendments to the 2022 California Green Building Standards Code (CALGreen), Part 11, Title 24, that will limit embodied carbon emissions in the “construction, remodel, or adaptive reuse of commercial buildings larger than 100,000 square feet and school projects over 50,000 square feet.”

“It can take up to 80 years to overcome embodied carbon’s impact through strategies that reduce energy usage or operational carbon; the planet doesn’t have that time,” said Los Angeles–based architect Scott Gaudineer, who serves as president of AIA California, the American Institute of Architects’ statewide chapter. “Today’s actions [by the Division of the State Architect and CBSC] codify a cultural shift: to meet decarbonization timelines set by California law, embodied carbon must be reduced in addition to operational carbon.”

According to the Carbon Leadership Forum, “embodied carbon” refers to carbon dioxide that is produced by building materials over their entire life cycles—including extraction, manufacture, transportation, installation, maintenance, and disposal—and is typically contrasted with “operational carbon,” or emissions that result from a building’s energy consumption while in use.

The new regulations, which will take effect statewide on July 1, 2024, expand the 2017 Buy Clean California Act (BCCA), which imposed embodied carbon limits for certain building materials in public works projects. The CBSC amendments greatly broaden the scope of buildings that were included in the BCCA and add concrete to the list of covered materials. The new code provides three paths to compliance: reuse at least 45 percent of an existing structure, employ materials that follow prescribed emission limits, or satisfy certain performance-based criteria in a whole building life cycle assessment.

William Leddy, founding principal of San Francisco–based Leddy Maytum Stacy Architects and vice president of Climate Action for AIA California, told RECORD that the CALGreen updates set the stage for future developments. 

“The plan is to move from 100,000 square feet down to 50,000 square feet by 2026, and to continue reducing so that, as we approach 2030, buildings at multiple scales will be required to account for their embodied carbon emissions,” Leddy explained. “We are hoping that this will help stimulate other code changes around the country.”

He noted that L.A. is on the verge of passing a whole building embodied carbon code that shares the same basic tenets as the new state regulations and includes residential projects.

The new code was developed over two years by the CALGreen Carbon Reduction Collaborative, a task force that united public and private stakeholders including representatives of several state agencies with the New Buildings Institute, the U.S. Green Building Council, and the non-profit Architecture 2030. Leddy asserts that the groundwork for this partnership was laid by a 2019 code change petition that AIA California submitted to the state.

“The American Institute of Architects California has been working for a number of years to help California move forward with decarbonization of our building stock, which contributes approximately 40 percent of our state’s greenhouse gas pollution,” said Sacramento-based architect Michael Malinowski, who approached the state about updating CALGreen, in the statement.

Over the coming months, AIA California will host programs that promote zero-net-carbon literacy and educate professionals on the new code.