The carbon emissions associated with materials used in the built environment, referred to as “embodied carbon,” are estimated to contribute up to 11% of all global energy-related carbon emissions.
According to a new report from sustainable development consultancy Arup, developed on behalf of the Natural Resources Defense Council (NRDC), California is one of the first states in the country to take meaningful steps toward slashing embodied carbon emissions from new buildings and some construction materials, and can set a course for clean materials production, procurement, and use across the United States.
The new report, Embodied Carbon Reduction Roadmap: Strategies and Policies for the State of California, analyzes the pathways and strategies for California to address embodied carbon in the built environment through policy action. Looking at different types of available strategies like building reuse and using low-carbon building materials, the report estimates the relative proportion of embodied carbon they can reduce across the buildings sector.
Legislative movement around embodied carbon in California is rapidly developing. Assembly Bill (AB) 2446, signed into law in 2022, directs the development of a framework for measuring and reducing the average carbon intensity of building materials with a target set of 40% reduction by 2035. Meanwhile, the public sector in California has shown market leadership in procurement of some low-carbon materials through the landmark bill AB 262, known as the Buy Clean California Act. More recently, code changes were approved for California’s statewide green building code (CALGreen) to include mandatory embodied carbon provisions for large commercial buildings and schools.
“It’s essential we transform construction materials from a carbon cost into a decarbonization tool, because we are not going to stop building anytime soon and a lot of the strategies studied will be deeply intertwined with both housing and energy transition efforts in the coming years,” said Lauren Kubiak, a senior scientist at NRDC. “These strategies and plans must begin now, because many of the strategies and technologies to decarbonize construction materials already exist but need a policy push to be more widely adopted.”
The report focuses on California and local governments within the state and concludes that strategies to reduce embodied carbon at the building level have the most reduction potential in the short term, while strategies to optimize procurement (i.e., material-level reductions) have the most reduction potential in the long term. While California has demonstrated leadership in low-carbon procurement of some materials through its Buy Clean California Act, the report said the omission of concrete in that policy represents a significant gap that should be addressed to realize the full potential of embodied carbon concrete reductions.
“The report emphasizes the importance of building codes as a crucial policy lever towards encouraging much-needed building-level embodied carbon reductions,” said Lauren Wingo, senior structural engineer at Arup. “Building code policies can direct designers towards more efficient resource use, which when paired with material-level decarbonization driven by Buy-Clean-type policies, sets us on a scalable pathway to net zero.”
It is estimated that, due to the rapid growth of new construction needed to meet the demand of growing populations, nearly half of the total carbon emissions from new construction from now until 2050 will be attributable to the embodied carbon of the built environment. Implementing these strategies can ensure that embodied carbon emissions decline and contribute to meeting climate goals.