In the last two decades, building designers, owners, and operators have become aware of the significant role that buildings play in global climate emissions. During that time, they have made admirable strides to reduce the amount of energy buildings consume, and the emissions associated with the creation of that energy. New buildings are also increasingly electrified, and as the electrical grid is decarbonized the energy supplied to them will be increasingly provided by renewable resources.
However, those who design, own, and operate buildings have the ability to influence another critical area of greenhouse gas emissions. While overlooked for most of the past decade, the emissions associated with extracting, processing, shipping, installing, and maintaining the materials used in the buildings is gaining increased prominence.
These emissions, known as embodied emissions, occur before a building opens, and can never be recovered. Often classified as “industrial,” the emissions are caused by the products purchased by those in the buildings industry.
The 2017 UN Environment Global Status Report predicts that by 2060, the world is projected to add 2.5 trillion square feet of new building stock. This is the equivalent of replicating New York City every month for 40 years. This is a staggering amount of construction. If we are to make near-term greenhouse gas reductions, we must develop ways to minimize embodied impacts. Specifically, the embodied carbon of buildings constructed during the next 10 years, in order to reach net zero carbon by 2050.
How Do We Respond?
“If you can’t measure it, you can’t improve it,” is a well-known quote in the business world, but it is critically important when applied to the tracking of embodied carbon. A fundamental piece of tracking embodied carbon is using a consistent way to measure embodied carbon to ensure the resulting comparisons are of functionally equivalent materials, assemblies, or buildings.
While developing the upstream data may be complex, there are ISO standards and processes to ensure the specifiers and purchasers are able to make comparisons based on consistent data. This data could take different forms, and may be presented in different ways, depending on the intended use. Regardless, it is determined by a method of environmental accounting called Life Cycle Assessment (LCA) that considers the energy and inputs that go into a process and the environmental outputs as a result of that process. The results of an LCA can be applied at either the product or building level. At the product level, an LCA usually results in an Environmental Product Declaration (EPD), which presents multiple environmental impacts, including global warming potential — embodied carbon — for a declared unit of a product. At the building level, it is referred to as a Whole Building Life Cycle Assessment (WBLCA) and includes data for multiple products.
Transparency Documents
In reference to EPDs, it is important to note they are one of an increasing number of transparency documents that are available for building materials. However, not all transparency documents provide the same information and may not be helpful for procuring lower carbon materials. EPDs report impact numbers for products, and allow teams to make comparisons on the basis of metrics like embodied carbon. Other transparency documents, such as Health Product Declarations focus on the ingredients within the product or processes. Ingredient documents are an important piece to better understanding issues of human health impacts and toxicity, but they do not contain information that allows teams to compare embodied carbon.
Which Areas Are Next?
Initially the discussion of embodied carbon has focused on structural and enclosure materials. The reason for this is two-fold. First, the structural and enclosure systems of a building contain a comparatively smaller number of distinct materials than other systems. Second, historical LCA comparisons that have been performed have shown significant impacts due to these systems. However, as the practice of performing WBLCA has matured, comparisons are increasingly including other building assemblies such as interiors and finishes as well as mechanical systems. Studies have illustrated important considerations, such as the rate of “churn,” or replacement for interior finished and furniture as well as the role of embodied carbon for elements of mechanical systems, such as refrigerants.
What Can an Owner Do?
An owner who wishes to address carbon should consider the following as they develop their reduction strategies and targets. Successful implementation will likely take multiple strategies, each addressing procurement aspects unique to specific project types.
At the Organizational Level
The first step is to see if, or how, embodied carbon is addressed in the organization’s climate plan or goals. Greenhouse gas emissions are categorized into “scopes” by the Greenhouse Gas Protocol, an internationally recognized accounting tool.
Scope 1 covers direct emissions from sources owned by an organization—such as fuel combusted or emissions from company vehicles. Scope 2 includes the emissions from electricity, steam, or other heating and cooling purchased by the company. Scope 3 includes all the other emissions that occur offsite, but that are a result of products or services purchased by the company.
Embodied carbon falls into Scope 3, however many current climate plans focus on Scope 1 and Scope 2. If your current plan does not include Scope 3, a good first step is to include it.
At the Building Level
When an organization is planning a large capital project, such as a new building, it is important to recognize that a large portion of the near-term emissions from this investment will be attributed to embodied carbon. The importance of embodied carbon should be articulated in the Owner’s Program Requirements and communicated in the project’s request for qualifications. This will allow respondents to highlight their past experiences and strategies to achieve reductions during the selection process. It is important to realize that while most sustainability rating systems, for example LEED, include credits that address embodied carbon, the systems are set up as a “menu” where design teams can choose which points to pursue. The project minimum, perhaps it is LEED Gold, does not necessarily ensure the project has reduced embodied carbon.
Organizations that own and develop multiple projects can also start to include requirements for design teams to measure and report the embodied carbon of their projects. This process allows owners to understand the range of embodied carbon in the projects they develop, and eventually set appropriate targets for future designs. While benchmarks for operational energy, and by extension embodied carbon, are understood across building typologies, there is not currently a robust data set to establish similar benchmarks for embodied carbon.
However, groups such as The Carbon Leadership Forum and SE 2050 are working to establish such benchmarks.
Designs could also include a requirement for a WBLCA to be performed or for the procurement of project materials to require certain materials. Furthermore, designs could include a certain percentage of the materials for the project to provide supply chain specific EPDs, or to use supply chain specific EPDs to demonstrate a product-by-product impact reduction from industry averages.
At the Product Level
Many of the strategies employed to reduce embodied carbon as part of a building design can be implemented for materials that an owner purchases directly for ongoing maintenance. The most applicable is to request that suppliers provide EPD for materials, and to inform suppliers that EPDs will be considered as an element of the procurement process. Including such a request can serve as a signal to the market regarding the importance of EPDs and also allow suppliers to highlight their efforts.
While initially some suppliers may not yet have EPDs, or will only have participated in an Industry Average EPD — where a group, usually a trade organization aggregates information from multiple participants into a single industry average — top performing suppliers often take the next step and create supply chain specific EPD’s for their products.
One example is the Embodied Carbon in Construction Calculator (EC3) developed by Building Transparency, which allows a user to quickly filter and see the availability of EPDs for a given product.
These tools and approaches are one of the many methods AEC professionals, regardless of their role in the industry, can use to address embodied carbon.
Dirk Kestner, PE, SE, LEED AP BD+C, ENV SP, is a principal and director of sustainable design at Walter P Moore. He can be reached at dkestner@walterpmoore.com.
