US Government Focuses on Embodied Carbon to Reduce Emissions

President Biden signed Executive Order 14057 in December 2021. Among the novel aspects of "Executive Order on Catalyzing Clean Energy Industries and Jobs Through Federal Sustainability" is the establishment of a Buy Clean Task Force. This task force will recommend ways to reduce carbon emissions associated with the construction phases for federal buildings, an important new development to reducing carbon emissions.

Operational Carbon vs. Embodied Carbon

Since the Carter administration, there have been executive orders that encourage increases in energy efficiency, which result in lowering operational carbon. This new executive order is the first federal-level recognition of the significant impact of carbon emissions associated with the other phases in the life of a building. Collectively, these are called embodied carbon and include emissions of all the steps of a building’s construction and life from extraction of construction materials through demolition, not including emissions produced during building use.

Embodied Carbon Elements within Life Cycle Analysis for Building Construction Materials

(Source: One Click LCA and Guidehouse Insights)

The Challenge of Accounting for Embodied Carbon

Embodied carbon is responsible for about the same amount of carbon emissions sent into the atmosphere as operational carbon. Three of the most common types of construction materials produce a prodigious amount of carbon. For example, each ton of cement that goes into a building’s foundation generates close to 1 ton of CO2 emissions. Each ton of steel that reinforces a building’s concrete foundation is responsible for between 3 tons and 4 tons of carbon emissions. The aluminum used in elevators generates up to 11 tons of carbon emissions. 

One of the challenges that has slowed the acceptance of the concept of embodied carbon are the variety of options that the construction value chain can use to calculate embodied carbon. For example, if 1 ton of freshly smelted aluminum is used, should it be saddled with the entire 11 tons of carbon or should some of the emissions be allocated to future uses if it is likely to be recycled? What if that batch of aluminum used in construction is made entirely from recycled soda cans? Should any of the carbon emissions from the first use be allocated for subsequent uses? Deciding these abstract issues is essential for proper accounting. 

Construction Industry Efforts to Address Embodied Carbon

The industry has already done a great deal of work on this topic. The New Buildings Institute has done some work to help modify building codes that consider embodied carbon in its report, Lifecycle GHG Impact in Building Codes. The organization Building Transparency has a software tool, the Embodied Carbon in Construction Calculator, that helps builders evaluate embodied carbon options for many common building materials and compare them against a baseline for each product category. 

Construction materials companies are acting by adding low embodied carbon options.  For example, U.S. Concrete offers its low carbon concrete and Lehigh Hanson has its EcoCem Portland Limestone Cement. Each uses techniques and ingredients that reduce carbon emissions from 20%-30% compared with standard cement. Nucor’s Econiq Steel takes it a step further, claiming zero net carbon by acquiring offsets for this brand of steel. 

The Federal Government Is Focusing on Embodied Carbon

The task force needs to make several important decisions. For example, will it create a new method for tracking embodied carbon or use one of the many options that are available? While the goal is zero net carbon emissions by 2050 as stated in the executive order, what are achievable interim goals? The important point is that attention to embodied carbon has started at the federal level.