We turn those materials into products that construction companies expertly assemble to create the spaces and buildings that support our lives. We do all of this without much thought as to how those materials are extracted, produced, manufactured, transported and installed. If we look closer, we see that it requires tremendous amounts of energy to construct a building and that every step in the building process results in carbon emissions. These emissions are commonly called embodied carbon.
Until recently we focused our attention on the energy used to power, heat, cool and ventilate buildings since those operational sources are significant. Building codes and standards have evolved to drive steady improvements in energy efficiency. We are now designing high-performance structures that operate on a fraction of the energy required by buildings built 10 to 20 years ago. These high-performance structures are helping building owners achieve the goal of net zero energy.
Now that we can deliver buildings that operate at net zero, where should we focus our attention next? Embodied carbon is the answer. It is imperative for the design, manufacturing and construction industries to address embodied carbon to meet societal carbon reduction goals. Based on research by Architecture 2030, worldwide we add about 6.13 billion square meters of new buildings per year which equates to 3,729 million metric tons of CO2. Between 2020 and 2050, embodied carbon emissions and operational carbon emissions will become roughly equivalent. In other words, embodied carbon’s portion of the life cycle carbon of our buildings is becoming a significant part of the total emissions equation. This is compounded by the fact that the decisions related to material choices and their inherent impacts happen at the beginning of a building’s life cycle and there is no way to change or reduce those impacts after construction.
The market is responding to the challenge through advancements in codes and requirements. One example is the City of Vancouver, British Columbia. The City has set a target to reduce embodied carbon emissions associated with new building construction by 40% by 2030 compared to a 2018 baseline. Vancouver plans to accomplish this by reusing and repurposing existing buildings and materials, constructing with wood and mass timber, requiring lower carbon concrete, powering construction sites with renewable energy and using low carbon insulation products.
The City of Los Angeles is taking tangible steps toward reducing embodied carbon. In an executive directive last year, the City announced it will adopt the Buy Clean California Act guidelines. The directive focuses on municipal construction projects and requires sourcing of products such as steel, glass and mineral wool insulation in ways that limit their global warming potential. For example, in the case of steel, one steel plant may use a portion of renewable energy and another plant may not. So even though the material is the same, it can have a different carbon footprint depending on where it’s sourced. The City will also examine including additional carbon-intensive building materials in the guidelines moving forward.
In addition to governmental actions, third-party standards are available for owners and construction project teams. The International Living Future Institute’s Zero Carbon certification covers both operational carbon emissions and the embodied carbon associated with building product choices. To achieve certification, the “embodied carbon emissions impact of the primary materials of the foundation, structure and enclosure have been reduced by a minimum of 10%, compared to a baseline scenario.” The Canada Green Building Council’s Zero Carbon standard requires an embodied carbon reduction of 20% less than the baseline. To calculate these reductions, teams will need to use a life-cycle assessment software tool. These tools estimate the carbon impacts of each of the primary construction materials, automating the process of calculating the overall embodied carbon of the building.
Embodied carbon tools include the Embodied Carbon in Construction Calculator (EC3), One Click LCA and Tally. One Click LCA and Tally offer interactivity with the design models produced by the architect and engineers allowing for potential time savings in building the LCA model. EC3 is free to use and includes the ability to import data from a design model. This tool allows the user to quickly run comparisons on some of the fundamental materials such as concrete, just by entering location data and selecting basic performance criteria for the concrete mix. The user can see examples of the emissions associated with specific mixes and concrete plant locations; this provides the basis for further research to support procurement decisions.
Over the past few years there has been a significant, collective realization that the design, manufacturing and construction industries must take a deeper look at carbon emissions and identify ways to reduce impacts. There is a significant opportunity for design and construction professionals to help decrease embodied carbon because the choices made during the design and construction phases of a project impact the building’s lifetime carbon footprint. By influencing material selection these professionals can help accelerate the adoption of net-zero buildings.