For the first time, California commercial and school projects will need to meet embodied carbon emission standards in a move seen as a potential model for other states.
New California regulations effective July 1 requires commercial and school projects to meet embodied carbon construction standards for the first time.
The revisions to California Green Building Standards Code (CALGreen) restrict the release of embodied carbon emissions during the “construction, remodel, or adaptive reuse” of commercial buildings larger than 100,000 square feet and school projects over 50,000 square feet. The regulations represent the first whole building lifecycle assessment (WBLCA) policy in the United States.
“These regulations are trying to make designers think about how to effectively and efficiently use resources,” said Ellen Mitchell, LPA Director of Sustainability and Applied Research. “It will force us to find areas within a design where we can make changes to help reduce a building’s environmental impact before construction even begins.”
The built environment is responsible for about 42% of annual global CO2 emissions, according to Architecture 2030. The regulations will push designers to consider whether to build or reuse, how much to build, and what kinds of material they are using.
“Most embodied carbon emissions are front-loaded into a project’s lifecycle,” attorney and sustainability consultant Nicole DeNamur recently wrote for the AIA. “By implementing strategies to reduce embodied carbon today, we are working in this critical time when we still have an opportunity to act.”
These regulations are trying to make designers think about how to effectively and efficiently use resources.” — Ellen Mitchell, LPA Director of Sustainability and Applied Research
Who is Affected?
New construction, renovations, and additions to commercial buildings over 100,000 sq ft and public schools over 50,000 sq ft will be subject to the new standards. Starting in 2026, the threshold for commercial buildings will lower to 50,000 sq ft.
What To Do
Buildings which fall into these categories have three options to comply with the updated code:
- Reuse 45% of the primary structure and enclosure, including roof framing, wall framing, and exterior finishes.
- Conduct a cradle-to-grave whole building life cycle assessment and demonstrate a 10% reduction in global warming potential (GWP) from a reference baseline building. Embodied carbon reductions can be captured through design optimizations, utilizing alternative low-carbon materials, and specification of product specific EPDs.
- Utilize a prescriptive approach for reducing embodied carbon by using building materials with a maximum GWP of 175% or less of the industry-wide GWP values. This includes structural steel, concrete, rebar, flat glass, and mineral wool insulation.
The new code also includes voluntary tiers which build upon the required options. These measures are for designers to go above and beyond what the California Building Standards Commission currently calls for. Voluntary tiers may also be adopted by local jurisdictions.
Tier 1
- Increases the threshold of the amount of building that is reused from 45% to 75%
- Requires a 15% reduction from baseline GWP, an increase from the mandatory 10% reduction
- Reduces the maximum GWP from 175% or less to 150% or less
Tier 2
- Increases the threshold of building reuse from 45% to 75% and requires 30% of interior, non-structural elements to be used as well
- Requires a 20% reduction from baseline GWP
- Reduces the maximum GWP from 175% or less to 100%
It’s up to the design team to determine appropriate, project-specific, baseline model assumptions.” — Jacob Gottlieb, LPA project Engineer
What’s the Impact?
The new requirements are relatively easy for projects to meet, but it is seen as an important step as California targets a 40% total carbon emission reduction by 2030.
“Building codes typically get introduced in a way that isn’t too limiting, but as time goes on, they get more and more stringent,” Mitchell said. “This update is likely the California Building Standards Commission’s first step toward creating stricter standards.”
For now, the regulations will likely have little financial effect on developers. In many cases, the best strategy for reducing embodied carbon — optimizing the usage of materials — can also reduce costs.
At this point, the code procedures for establishing baselines are not completely solidified. The standards refer to “reference baselines” to derive a reduction in GWP. However, there is no clear definition of a universal reference baseline, which is dependent on region, project type, and building materials.
“It’s up to the design team to determine appropriate, project-specific, baseline model assumptions,” said LPA project engineer Jacob Gottlieb. “Industry guidance for establishing baselines is being developed now, but it’s not at a point where we have something concrete to work off of.”
What to Think About
There are a few strategies developers can take to follow the new guidelines while considering cost.
1. Minimize material. Minimizing materials is a useful strategy for meeting the new construction standards. Using lower GWP materials reduces a building’s embodied carbon footprint. It can also be cost-effective.
2. Strategically make aesthetic choices. Some design features may need to be reevaluated. “Right now, we might see a 30 ft cantilever as a nice design option from an aesthetic perspective,” says LPA structural engineering design coordinator Aron Tezveren-Johnson. “But from an embodied carbon standpoint, that might be a negative design decision. Moving forward, we will need to consider the GWP impact of more complex design features as part of our process.”
3. Start with the big-ticket items. A good rule of thumb is to start where there are large quantities of material, and often large dollar signs. For items such as steel and concrete, even small reductions in embodied carbon emissions associated with manufacturing can add up to a significant impact due to volume alone.
4. Start planning now. Although some projects may not fit into the new criteria now, they may in the future. In 2026, the criteria for commercial buildings will lower from 100,000 sq ft to 50,000 sq ft. Building codes are predicted to get stricter in the future, and planning to implement the mandates and voluntary tiers into a design will push a project in the right direction for a future of reduced emissions.
Related: Strategies for Attacking Embodied Carbon
