The state of California will issue new rules limiting the embodied carbon allowed in commercial buildings larger than 100,000-sq-ft in area and school projects over 50,000-sq-ft.
Embodied carbon means the greenhouse gasses emitted by building materials over their entire lifespan, from manufacturing and transport to installation and disposal.
The 11 commissioners of the California Building Standards Commission voted unanimously in favour of the rule change, to be contained in an intervening code supplement to the 2022 California Building Standards Code.
The commission has not said what the limits are to be. It said it would publish them by 1 January 2024 and they will take effect across the state on 1 July 2024.
The American Institute of Architects was among the bodies consulted for the proposed changes.
Its president Scott Gaudineer welcomed the decision, saying: “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.
“Today’s actions… codify a cultural shift: to meet decarbonisation timelines set by California law, embodied carbon must be reduced in addition to operational carbon.”
In September 2022, AB 2446 was signed into law in California, stipulating that non-residential buildings over 10,000-sq-ft and residential developments with over five units would be subject to building material assessments.