By: Avideh Haghighi, AIA, LFA

All eyes were on California earlier this month when the state became the first in the nation to adopt unprecedented changes to limit embodied carbon in non-residential buildings and K-12 schools. The new measures build on the Golden State’s legacy as a leader in the climate crisis and provide an exciting potential to shape the future of green building code in the United States.

As a steering committee member of the AIA California Climate Action Committee, I had the distinct pleasure of championing these measures, including providing real-world examples of ZGF’s low-carbon projects to showcase market readiness and feasibility of the proposed measures. 

Given that the built environment accounts for 40% of global greenhouse gas emissions, one of the most significant ways to reduce impact is adoption of building codes to ensure all buildings meet a baseline carbon criterion for both operational and embodied carbon. While operational carbon is now well-understood and actively addressed with energy codes, embodied carbon – emissions related to the production of materials that make up our buildings – has been largely absent from code regulations until now.

CALGreen Sets the Bar
California’s Green Building Standards Code, often referred to as “CALGreen,” is part of the California Code of Regulations. First introduced in 2007, CALGreen was the first-in-the-nation green building standards code and set an extraordinary standard for minimizing impacts of buildings on the environment. Subsequent code adoptions have only strengthened California’s leadership in addressing the climate crisis. This most recent change further demonstrates a path to achieving the State’s carbon neutrality goals.

Set to take effect July 1, 2024, the new mandatory measures will limit the embodied carbon emissions in the construction, renovation, or adaptive reuse of non-residential buildings larger than 100,000 SF and K-12 school buildings over 50,000 SF. These mandatory measures will be adopted into the 2022 California Green Building Standards Code, Title 24, Part 11, accompanied by more ambitious voluntary Tier 1 and Tier 2 measures.

Compliance Pathways & Demonstrations
Project teams can follow one of three compliance pathways outlined in the code to reduce embodied carbon emissions in building design and construction. Notably, each pathway was made possible by low-carbon and net zero precedent projects throughout the state.

Reuse: One of the highest impact ways to reduce a project’s embodied carbon is to update and adapt existing structures. When reusing a building, the project team must retain at least 45% of an existing structure.

For California State University, Los Angeles Student Services Building, ZGF salvaged the university’s seismically damaged mid-20th-century lab building that was scheduled for demolition and repurposed it into an administrative and student-services building. Reusing the existing 8-story, 218,000 SF structure resulted in 6,800 tons of carbon savings – a 29% embodied carbon reduction.

Performance: For new buildings, teams can perform a whole building lifecycle analysis, a method that takes stock of building emissions at every stage to demonstrate a 10% reduction in global warming potential (GWP). Project teams can make use of several free, open-source tools to accurately assess a project’s total impact.

At the California Air Resources Board Southern California Headquarters, ZGF designed a cutting-edge vehicle testing facility that is also a landmark example of California’s climate policies in action. The team achieved a 10% whole building embodied carbon reduction through specifying and procuring low-carbon concrete. Our team performed a life cycle assessment in-house to quantify the reductions.

Prescriptive: As architects and designers, we can directly impact embodied carbon of buildings through selection and procurement of low carbon materials. The prescriptive path addresses building material embodied carbon by using documentation from environmental product declarations (EPDs) to meet global warming thresholds set by the statewide Buy Clean California Act (BCCA).  BCCA limits emissions for structural steel, concrete reinforcing steel, flat glass, and mineral wool board insulation as well as concrete mixes.   

The Richards Boulevard Office Complex in Sacramento will be home to 5,000 State of California employees and the largest all-electric, net zero carbon building complex in the U.S. when complete. To demonstrate how a campus of this scale and complexity can minimize its carbon footprint the team utilized EPDs to procure low-carbon materials and specified a low carbon concrete mix for a 5% GWP reduction in the project’s structural concrete.

Collaboration for Change
One of most significant achievements for this implementation is that it occurred during an interim code cycle – a one and half year cycle that is typically reserved for minor updates. Recognizing that there is no time to wait, the California Building Standards Commission established a Carbon Reduction Collaborative working group, comprised of industry leaders and subject matter experts that helped shape the new code language.

The changes were also made possible through collaborative efforts between AIA California, Rocky Mountain Institute, New Buildings Institute, USGBC and other allied organizations, demonstrating the powerful role architects can play in shaping building codes. For more information about how to get involved in future code cycles, contact your local and statewide AIA chapters.

The Path Ahead
Embodied carbon makes up 28% of global building industry emissions, and 11% of annual GHG emissions. We have already demonstrated that low-carbon buildings are achievable at every scale, both here in California and around the world. Making meaningful reductions at scale and in time to avert the worst impacts of the climate crisis will require implementing restrictions on embodied carbon in our built environment. With California leading the charge, we hope other state building codes soon follow. 

Avideh Haghighi is a sustainable design leader and architect in ZGF’s Los Angeles office. She is a current AIA California Climate Action steering committee member and USGBC-LA board member.

To learn more about the path to CALGreen’s recent code changes, join me at the Net Zero Conference on Thursday, September 14 for my session: Embodied Carbon: Moving From Concept to Code.