As we approach summer and prepare for the upcoming 4th of July holiday, mark your calendars for July 1, 2024, as it signifies a pivotal moment in the history of the building industry in the US. On this date, California will implement a new regulation concerning embodied carbon, which will be enforced by CALGreen and/or county permits. These regulatory amendments, integrated into the 2022 California Green Building Standards Code (CALGreen), Part 11, Title 24, expand upon the Buy Clean California Act (BCCA) of 2017.
The building industry has primarily focused on energy efficiency and consumption, measured in conventional metrics such as kilowatt-hours (kWh), therms, or energy costs ($). However, embodied carbon takes a broader perspective, considering the environmental impact of a building’s entire lifecycle, from extraction and manufacturing to transportation, maintenance, and end-of-life disposal. CO2 emissions serve as a unified environmental impact metric for both operational and embodied carbon. It’s noteworthy that approximately 40% of annual global CO2 emissions stem from building operations (27%) and embodied carbon (13%).
The new California code serves as a wake-up call for the industry to adopt a more comprehensive approach. Initially, the embodied carbon regulation will apply to commercial projects larger than 100,000 square feet and long-term structures like schools exceeding 50,000 square feet. California offers three compliance pathways:
- Reuse: This initial pathway aims to minimize unnecessary CO2 emissions by utilizing existing structures, thereby avoiding the wasteful use of materials and resources associated with new construction processes, including excavation, manufacturing, and transportation. At least 45% of an existing structure must be reused to meet this requirement.
- Prescriptive: This straightforward approach involves adhering to specified emission limits outlined through Environmental Product Declarations (EPDs) for a handful of important materials. EPDs, similar to nutrition labels, summarize a product’s environmental impact and must demonstrate Global Warming Potentials (GWPs) limited to less than 175% of the industry average (130% for concrete). The materials that need to comply prescriptively include: structural steel, concrete reinforcing steel, flat glass, mineral wool board insulation, and concrete.
- Performance: This pathway involves conducting a Whole Building Lifecycle Assessment (WB LCA), which evaluates the cradle-to-grave emissions of the entire building. A 10% reduction in global warming potential must be achieved through a comprehensive Life Cycle Assessment (LCA), following ISO 14040 methodology.
While California is implementing this new regulation, other sustainability platforms, such as LEED, are encouraging the study of embodied carbon in projects. Interestingly, the inclusion of glass is not mandatory in LEED’s Life Cycle Assessment, but fortunately, glass has been added to California’s embodied carbon reduction regulation. This is a significant addition, as glass plays a crucial role in the floor-to-ceiling designs common in modern architecture.
While California leads the way, other city jurisdictions are allowed to adopt tougher standards (labeled “Tier 1” and “Tier 2”) for different building types, areas, and reduction rates. For instance, Santa Clara County plans to require Tier 1 compliance for larger projects with a 15% reduction.
Verdical Group has conducted numerous LCAs for various building types. After reviewing these studies, we conclude that most of our projects should be able to comply with this new code prescriptively (path 2) and through setting actionable goals early on, many can comply through the performance approach (path 3). Although this regulation adds another task to project teams’ to-do lists, the current GWP thresholds for materials are not too stringent to meet with current building materials and practices in California.
In conclusion, these regulatory changes underscore the need for clear and actionable goals throughout project design. As legislative efforts to reduce embodied carbon become more widespread, the normalization of material-specific EPDs is anticipated, encouraging a more sustainable approach to construction practices and promoting environmental responsibility within the industry. For more information on embodied carbon and LCAs, you can refer to our “What is an LCA?” article.
