California Air Resources Board

California has committed to reducing GHG emissions by 40 percent below 1990 levels by 2030 and achieving carbon neutrality no later than 2045.^[1] Since buildings are a large source of GHG emissions, building decarbonization is a high priority in California state policy.^[2],[3] California has made (and continues to make) considerable progress in reducing GHG emissions from buildings through energy efficiency, clean renewable energy, and building electrification. As a result, embodied carbon in the materials used to construct buildings represents an increasingly large share of remaining building-related emissions, accounting for up to 50 percent of total GHG emissions.^[4],[5]  Embodied carbon refers to the lifecycle GHG emissions resulting from the extraction, manufacturing, transportation, installation, maintenance, and disposal of goods, including building material goods.^[6]  Tackling embodied carbon in new construction immediately is critical for ensuring that California can achieve its housing and climate goals, because housing production in California is anticipated to ramp up significantly over the next 10 years.^[7]

In September 2022,Governor Newsom signed Assembly Bill 2446 (Holden), which requires CARB to develop a framework for measuring and reducing the embodied carbon of building construction materials, primarily at the materials production stage, with a target of a 40 percent net reduction in GHG emissions no later than the end of 2035. Assembly Bill 43 (Holden), signed in October 2023, builds upon the foundation of AB2446 and provides CARB the option to utilize an embodied carbon trading system as a potential path to implement AB 2446. 

CARB is required to develop a comprehensive strategy to ensure feasible and low-cost-impact alternatives to achieve the reduction targets. CARB will also collaborate with energy and building standards agencies and leverage the CALGreen Carbon Reduction Collaborative (CCRC)^[8]  that the California Building Standards Commission (BSC) initiated to discuss the lifecycle performance of buildings as potential voluntary measures during the 2022 Intervening Code Cycle of the California Green Building Standards. As part of this work CARB will evaluate several options on how to achieve the mandates in AB 2446.

[1] Governor Newsom. 2022. “Governor Newsom’s Ambitious Climate Proposals Presented to Legislature.” Available at: https://www.gov.ca.gov/2022/08/12/governor-newsoms-ambitious-climate-proposals-presented-to-legislature/.

[2] California Air Resources Board. 2022. “Draft 2022 Scoping Plan Update – Achieving Carbon Neutrality by 2045.” Available at: https://ww2.arb.ca.gov/our-work/programs/ab-32-climate-change-scoping-plan.

[3] California Energy Commission. 2022. “Final 2021 Integrated Energy Policy Report.” Available at: https://www.energy.ca.gov/data-reports/reports/integrated-energy-policy-report/2021-integrated-energy-policy-report.

[4]Esau, R., M. Jungclaus, V. Olgyay, and A. Rempher. 2021. "Reducing Embodied Carbon in Buildings: Low-Cost, High-Value Opportunities." RMI. Available at: https://rmi.org/insight/reducing-embodied-carbon-in-buildings/.

[5] California Energy Commission. 2022. “Final 2021 Integrated Energy Policy Report.” Available at: https://www.energy.ca.gov/data-reports/reports/integrated-energy-policy-report/2021-integrated-energy-policy-report.

[6] Carbon Leadership Forum. 2022. “Embodied Carbon Policy Strategies: Presentation.” Available at: https://efiling.energy.ca.gov/GetDocument.aspx?tn=239465&DocumentContentId=72929.

[7] Housing and Community Development. 2022. “Regional Housing Needs Allocation.” Available at: https://www.hcd.ca.gov/regional-housing-needs-allocation.

[8] Building Standards Commission. 2022. “Pre-Cycle Activities—2022 Intervening Code Cycle: CALGreen Carbon Reduction Collaborative.” Available at: https://www.dgs.ca.gov/BSC/Rulemaking/2022-Intervening-Cycle/2022-PreCycle.