For business owners and facility managers, supporting sustainability by reducing carbon emissions is a battle on two fronts. The first, which targets operational carbon, has traditionally been the primary focus of facility management and involves reducing the emissions generated by energy used in building operations.
The second front is embodied carbon, which involves the carbon emissions resulting from the construction, renovation, and refurbishment of buildings. While embodied carbon has not received nearly the attention of operational carbon, inspiring some experts to refer to it as the “silent threat” in the war on climate change, that is about to change.
In August 2023, California raised the stakes on embodied carbon when it became the first state to mandate reductions in embodied carbon emissions as part of its building code. The update to the California Green Building Standards Code, which was driven by the advocacy of architects and building industry experts in the state, takes effect on July 1, 2024.
Embodied carbon is the term used to describe the carbon emissions that flow from the production of materials used in the built environment and, for the most part, involves processes that contribute to the construction of a building. Processes used for the extraction of raw building materials, such as steel, timber, and concrete, contribute to embodied carbon. Carbon emissions that result from the transportation of materials to building sites are also considered embodied carbon, as are the emissions produced by construction activity.
Embodied carbon also plays a role post-construction when buildings are renovated, remodeled, or refurbished. Projects that replace major structural elements like beams, floors, or roofs can contribute to embodied carbon emissions. End-of-life management also contributes to embodied carbon emissions, especially for large-scale demolition projects.
In the U.S., the construction industry is a major contributor to carbon emissions, accounting for nearly a third of the total. According to the U.S. Environmental Protection Agency, embodied carbon emissions make up 11 percent of the total amount of construction emissions.
The California Green Buildings Standards Code, otherwise known as CALGreen, contains mandatory and voluntary measures designed to promote sustainable building practices for both residential and commercial projects. It is focused primarily on energy efficiency, water efficiency, material conservation, resource efficiency, and indoor air quality.
CALGreen’s new embodied carbon mandates apply to non-residential projects that exceed 100,000 square feet and school projects that exceed 50,000 square feet. Projects in that range that also fall under the authority of the Divisions of the State Architects, and that are seeking building permits after July 1, will be required to meet one of three compliance pathways defined by the code.
The first pathway is for projects involving building reuse, which will be required to reuse at least 45 percent of an existing building’s structure and exterior. When reuse projects are combined with new construction, the new building cannot exceed twice the size of the existing structure.
The second pathway allows for compliance to be achieved through a whole building life cycle assessment. To satisfy this requirement, the project must demonstrate 10 percent lower carbon emissions than a baseline project design of a similar construction type.
The third pathway, which is described as prescriptive, is focused on products’ global warming potential. Projects will need to comply with Buy Clean California limits with concrete added to the list of BCCA materials. The BCCA focuses on reducing carbon emissions linked to the manufacturing of structural steel (including hot-rolled sections, hollow structural sections, and plate), concrete reinforcing steel, flat glass, and mineral wool board insulation.
To satisfy the prescriptive path, builders and designers must understand a key concept in the climate science space, which is known as Global Warming Potential (GWP). GWP serves as a metric for gauging the amount of thermal radiation absorbed by a greenhouse gas within a specified timeframe after its introduction into the atmosphere. GWP is represented as a multiple of the radiation absorbed by an equivalent mass of carbon dioxide (CO2), which serves as the reference gas.
The new CALGreen mandate on embodied carbon requires GWP levels to be documented with Environmental Product Declarations (EPDs), which are standardized reports developed by independent organizations to determine and communicate the environmental impact of a product throughout its entire life cycle.
While the new CALGreen mandates promise to significantly advance sustainability in California, as well as motivate the adoption of similar measures in other locations, they represent just one of many steps being taken to combat climate change in the building industry.
Energy efficiency is another main component of sustainability that seeks to reduce emissions from energy consumption. Forward-thinking eco-conscious construction initiatives encourage builders to adopt measures such as building envelope enhancements that improve thermal performance. Leveraging renewable energy and integrating high-efficiency lighting and heating/cooling systems are other components of such initiatives.
Water efficiency is another key component of sustainability that is addressed in green building ordinances and third-party certification systems. Measures that have been shown to make a difference in this area include the use of water-saving plumbing fixtures and a focus on efforts to detect and repair leaks. Implementing greywater reuse systems is another step that can improve a building’s sustainability along with harvesting rainwater.
Providing education and training to tenants and building staff is a great step that facility managers can take to support sustainability efforts. This begins with communicating the importance of energy and material efficiency and the commitment that the building has to play a role in the battle against climate change. Explaining to tenants the steps that have been taken to improve sustainability and the impact that they are having can encourage them to support efforts. Encouraging tenants to take an active role in identifying, reporting, and monitoring energy usage along with maintenance issues supports efforts to avoid unnecessary energy and water waste.
The new CALGreen mandates mark an exciting step forward in the state’s efforts for climate action relevant to the built environment, calling builders to begin adopting embodied carbon reduction measures early in the development process when key decisions about building parameters and materials are being made. By doing so, they have the potential to shift the entire culture of the industry toward a greater appreciation for and commitment to environmental responsibility.
Hafsa Burt, Founder of hb+a Architects, is a practicing architect with 24 years of design experience in carbon-neutral and regenerative buildings. She is well-known for her expertise in eliminating toxins in indoor air quality, zero carbon/zero energy expertise, and her legislative advocacy work to promote sustainability in the built environment for the past 18 years.
