Since 2008, individuals, businesses, industries, organizations, policymakers and other advocates working toward a healthier, fully sustainable planet have leveraged the momentum of Zero Emissions Day. Held this year on Sept. 21, the day’s name typically evokes similar imagery of the challenge in front of us. Industrial stacks spewing black smoke. Traffic jams under a cloud of tailpipe emissions. Smog as a permanent element in cityscapes. Missing from these images are the less obvious, unseen sources of carbon emissions that are part of our daily lives. One striking example is the carbon footprint of building and construction materials throughout their life cycles—from manufacturing and transport to use and end of life.
Typically, we focus on addressing operational emissions, like the energy used to heat and cool a building. However, steel, lumber and most other construction materials are often a significant source of embodied carbon, which factors in emissions from the manufacturing, transportation, installation, maintenance and disposal of these materials. Although not as noticeable, it is still a significant carbon debt we owe Mother Nature. Fortunately, there are ways to repay it—and pay it forward for our collective future.
To do so, we must assess the specific impacts of building materials and holistically approach the entire value chain in the built environment.
Assessing the Impact of Building Materials
In our new climate reality, it is important to connect the dots between the outside and the inside. We know that climate change affects our outdoor environment, but those same issues—air quality, extreme temperatures, coastal flooding—also increasingly require us to protect our indoor environments. However, in doing so, we must not worsen carbon emissions, but instead focus on new ways to responsibly build and construct the places in which we live, work, learn, heal and play.
Step one is to assess the carbon impact of building materials. One of the most meaningful ways is via a Life Cycle Assessment, which provides insight into the impact of products throughout their life cycle. These materials can then be optimized to mitigate the impact of embodied carbon by improving raw material sourcing, energy and water use, and recycling streams.
Once an LCA has been conducted, the next step is to use an Environmental Product Declaration to allow architects, consumers and other stakeholders to compare the environmental impacts of different materials. This transparent communication enables procurement and purchasing functions to make the most sustainable decision for a project.
Third, it’s worth exploring emerging resources to support efforts in this arena. Industry groups are beginning to develop enhanced tools that can help materials manufacturers, builders and designers understand how to best assess the impacts of embodied carbon. For example, the Embodied Carbon in Construction Calculator, co-conceived by Skanska USA and C Change Labs, represents the first third-party-verified database of EPDs. This tool facilitates easy comparison of embodied carbon emissions from construction materials and products.
Taking a Holistic Approach
To best address embodied carbon, we need a holistic perspective that not only considers the construction or operational emissions of a building, but also allows for a critical assessment of the emissions of the whole value chain. This includes the manufacturing process as well as the resources and energy it takes to maintain the structure over its life. It also includes the disposal or recycling of materials when the building is demolished. These can be complex and often frustrating issues, but they are of great importance if the built environment is to reach net-zero emissions. Consider the following components, which offer a solid foundation for taking a holistic approach.
Embodied carbon can be reduced significantly at the planning stage. And the best way to reduce it is to reuse existing structures instead of constructing new ones. So, architects and designers should ask themselves, “Can we repurpose an existing structure instead of building a new one?” This alone can save up to 75% in embodied carbon emissions.
In addition, building renovations can be a significant contributor to embodied carbon emissions. The interior may go through multiple renovations over the lifetime of the building. These cyclical renovations can, over time, contribute more to the embodied carbon emissions of a building than the actual construction process. For example, ceilings and ceiling tiles take up a large portion of a building’s interior space. Replacing them can result in significant embodied carbon emissions.
Strategies to reduce embodied carbon include choosing low-carbon interior finishes (like ceilings) and limiting carbon-intensive materials in new buildings or renovation projects, as well as choosing materials like wood or bamboo, which can sequester carbon over their life cycle. Reusing or salvaging items, like wooden beams, bricks and metals, also reduces the energy spent on manufacturing and transporting new products.
This year, I encourage you to consider Zero Emissions Day as your “new leaf” in efforts to reduce your carbon footprint. That is, start looking at carbon emissions on the inside as well as the outside. We must shift our thinking and take an all-inclusive approach to assessing the climate impact of the built environment. Doing so will lead to more sustainable buildings, the downstream effects of which will create entire cities and communities that are more sustainable and healthier places to live.