Embodied Carbon Reduction in the Built Environment

Earlier this year, the US passed the Inflation Reduction Act of 2022, with $369 billion in funding intended to cut climate pollution in half by 2030 (from 2005 levels). The private sector is also embracing capital-allocation strategies that take environmental, social, and governance (ESG) issues into account with their business practices. Over the next few years, both the federal government and the private sector will make significant expenditures to reduce the amount of greenhouse gas emissions from the facilities they build and operate.

Built Environment Contributes to Climate Change

If the US is to meet the above commitment to reduce carbon emissions, the built environment will have to respond. There are two ways the built environment contributes to climate change.

Facilities generate greenhouse gas emissions

This is the most well known contribution of the built environment to climate change since facility operations require significant energy. Architects will be required to design climate smart, low, and clean energy facilities. Improvements to the power grid with cleaner energy sources that eliminate natural gas can rapidly reduce greenhouse gas emissions due to facility operations. The Alliance to Save Energy[1] estimates that around 40% of the energy consumed in the US, and a similar percentage of greenhouse gas emissions, comes from building operations. With improved efficiencies and the transition to cleaner energy sources with battery storage capacity, the percentage of greenhouse gas emissions due to facility operations will decrease in the coming years.

Building materials have embodied carbon

Another source of greenhouse gas emissions is the embodied carbon in building materials. Embodied carbon consists of all the greenhouse gas emissions associated with building construction, including those emissions that arise from the extraction, transportation, manufacturing, installation on site, operation, and end-of-life of building materials. If governments and the private sector are to make meaningful strides towards reducing greenhouse gas emissions, architects will have to transition to lower carbon-intensive building materials and be prepared to document the embodied carbon of the facilities they design. Industry professionals anticipate[2] that there will be increased scrutiny on the use of materials that have high-embodied carbon with a focus on reducing carbon-intensive materials or choosing lower carbon alternatives.

Limit Carbon-Intensive Materials

In the coming years, owners will increasingly seek to limit carbon-intensive materials, such as concrete and steel.

Concrete

Concrete is one of the highest carbon-intensive building materials. Cement is carbon-intensive because it requires high processing heat during its manufacture, which releases CO₂. Efforts are underway in the concrete industry to replace prescriptive specifications[3] that require a set amount of cement with performance specifications that minimize cement content and focus on performance measures like maximum shrinkage, permeability, and the required ultimate strength for when the facility is in service. Switching from prescriptive to performance specifications will require more involvement from local contract suppliers, contractors, and the authority having jurisdiction over the project.

Steel

Steel is another carbon-intensive material. Steel production is an energy-intensive process that requires high temperatures to transform iron ore into steel. Traditional steel plants still use coal to create molten iron, which requires purification. As owners focus more on the amount of embodied carbon in their facilities, architects will have to pay greater attention to their source of steel and specify that recycled steel play a more prominent role in sourcing decisions.

Choose Lower Carbon Alternatives

Mass Timber

Mass timber is an engineered wood product manufactured off-site that can be built to similar strength ratings as concrete and steel while weighing significantly less. Assuming that wood is sourced from farms that have sustainable timber harvesting, mass timber solutions emit fewer greenhouse gases than steel and concrete, making it an alternative for owners who want to reduce the embodied carbon in their facilities. Mass timber is gaining in acceptance across the US.[4]

Modular Construction

Modular construction has proven to be less carbon-intensive[5] when compared to concrete and steel. The production of modules off-site in a controlled assembly line environment and assembled on-site substantially lowers indirect carbon emissions, such as those caused by deliveries and on-site workers. The proximity of a manufacturing facility to the project site determines whether modular construction is a viable solution.

Inflation Reduction Act Will Accelerate Use of Low-carbon Materials

The Inflation Reduction Act (Act) authorizes the federal government, one of the largest purchasers of materials in buildings, to purchase low-carbon materials for federal projects. There are multiple efforts underway[6] to standardize environmental impact disclosures, labeling, and verification of low-carbon concrete and construction materials.

The Act allocates $250 million to the Environmental Protection Agency (EPA) to support the development of standardized, high quality, and transparent environmental product declarations of greenhouse gas emissions associated with construction materials, as well as another $100 million to identify and label low-carbon construction materials used for federal buildings and federal transportation projects. These efforts will provide a wealth of information for architects tasked with providing design solutions with low embodied carbon.

Be Proactive About Practice Management Challenges

Delivering design solutions that have low embodied carbon will require additional time for architects to do the necessary comparisons of feasible alternative solutions. It is essential that architects present meaningful choices to their clients on the proposed alternatives, including cost and schedule implications. Architects should take the time to educate their clients about the available solutions and manage expectations about reductions in embodied carbon.

During the evaluation of alternative materials, architecture firms should always rely on technical data instead of the promotional literature that manufacturers produce. It is essential that firms ask manufacturer representatives for the positive and negative results of the usage of their products. To the extent possible, firms should ask for information on comparable projects that will help them evaluate the actual performance of the alternative materials. Either the contractor, owner, or the architect must document the sourcing and installation of low embodied carbon products and solutions so that the completed facility meets the owner’s goal of reducing embodied carbon.

[1] Source: Alliance to Save Energy, https://www.ase.org/categories/buildings#:~:text=The%20Issue,proportion%20of%20greenhouse%20gas%20emissions.

[2] Source: McKinsey and Company, “Call for action: Seizing the decarbonization opportunity in construction,” https://www.mckinsey.com/industries/engineering-construction-and-building-materials/our-insights/call-for-action-seizing-the-decarbonization-opportunity-in-construction.

[3] Source: Carbon Cure, “Concrete Expert Dr. Michael Thomas Makes the Case for Performance-Based Specs,” https://www.carboncure.com/concrete-corner/concrete-expert-dr-michael-thomas-makes-the-case-for-performance-based-specs/.

[4] Source: Building Design + Construction, “Cross laminated timber market forecast to more than triple by end of decade,” https://www.bdcnetwork.com/cross-laminated-timber-market-forecast-more-triple-end-decade.

[5] Source: Archinect, “New study finds that modular construction produces 45% less carbon than traditional methods,” https://archinect.com/news/article/150313447/new-study-finds-that-modular-construction-produces-45-less-carbon-than-traditional-methods.

[6] Source: White House, “FACT SHEET: Biden-⁠Harris Administration Announces New Buy Clean Actions to Ensure American Manufacturing Leads in the 21st Century,” https://www.whitehouse.gov/briefing-room/statements-releases/2022/09/15/fact-sheet-biden-harris-administration-announces-new-buy-clean-actions-to-ensure-american-manufacturing-leads-in-the-21st-century/.

Victor and CNA work with the AIA Trust to offer AIA members quality risk management coverage through the AIA Trust Professional Liability Insurance Program, Business Owners Program, and Cyber Liability Insurance program to address the challenges that architects face today and in the future.