The 39% of total global energy-related carbon emissions due to buildings has been widely reported. Less known, however, is that an eye-opening 11%—more than a quarter of that total—are scope 3 emissions. These indirect emissions come mainly from the extraction, manufacture, delivery, installation and end-of-life disposal of materials, according to the International Code Council.
“Scope 3 emissions are hard to measure and even harder to manage,” said Sara Neff, head of sustainability for Lendlease Americas, during an interview with the Built Blog. “But we know that more than 90% of our emissions are scope 3.”
Lendlease is not alone. But before reducing scope 3 emissions, construction firms must measure them. In its “Baseline Embodied Carbon 2022 Report,” Turner Construction, a top U.S. green builder and contractor, made a solid effort to do just that. The study quantifies greenhouse gas (GHG) emissions associated with a sample of the footprints and materials for the firm’s projects.
To learn more, Built spoke with Rowan Parris, embodied carbon program manager at Turner Construction.
Built: What prompted Turner to conduct the study and report on your embodied carbon baseline?
Parris: We saw a unique opportunity to contribute meaningful data on embodied carbon to the industry at large, and to use that data ourselves to set impactful and realistic reduction targets for our projects and operations. We use the Embodied Carbon in Construction Calculator (EC3) Tool because of its robust database of Environmental Product Declarations (EPDs) and ability to filter average results based on project and material characteristics, like location or strength class.
Built: Does Turner consider embodied carbon the greatest challenge to reducing your own carbon footprint—and that of the rest of the construction industry?
Parris: Embodied carbon is likely to be the largest single piece of our scope 3 reporting categories. Turner has already taken steps to reduce our scope 3 emissions through a range of efforts, including reducing business travel and offering employees a flexible work policy that enables people to work remotely. These policies reduce our overallscope 3 emissions, but they also increase the relative impact of embodied carbon.
The 2022 Baseline Report homed in on “upfront” embodied carbon associated with upstream material manufacturing. But embodied carbon also includes emissions associated with transportation, the construction process itself and deconstruction and demolition impacts.
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Turner’s jobsite metering program is the most robust in the industry, with more than 150 projects tracking fuel, electricity and water consumption. Through this program, we have gained key insights into GHG-intensive activities on our construction projects. We have begun to address these sources through collaboration with original equipment manufacturers (OEMs), rental partners, trade partners and clients.
We have been tracking construction and demolition waste for more than a decade and have committed to increasing our landfill diversion percentages on a 10-year path to zero construction waste. We routinely recycle, use manufacturer take-back and recovery programs, separate our waste streams and train our trade partners in methods to optimize landfill diversion.
Built: What analysis did you do of additional materials used in construction—such as aluminum, glass, insulation and wood?
Parris: We focused our first benchmark report on the materials with the highest emissions and best available data. We are also tracking other materials on projects with client- and legislative-driven reduction targets. The materials of focus vary depending on the specific goals of the project and range from concrete and steel to all materials needed to achieve LEED pilot credit for Procurement of Low Carbon Construction Materials.
Built: You evaluated many characteristics, from gross floor area and project revenue to geography and seismic category, to find the main drivers of embodied carbon in your projects. Was only one statistically significant?
Parris: A key predictor is a profoundly helpful tool to make high-impact decisions early in a project’s development. The only statistically significant relationship was embodied carbon intensity per floor area. Perhaps with more projects and broader material scope, we’ll see different statistical trends in future reports.
Built: What’s new for the 2023 Baseline Report?
Parris: First, in alignment with Turner’s public environmental, social and governance (ESG) commitments, we expanded the materials to include concrete, steel, asphalt, glass and wood. This enables us to see a more complete picture of the buildings included in the study based on the data available in the industry. Embodied carbon data is evolving quickly as manufacturers ramp up EPD publication to meet rising demand. We plan to continuously evaluate additional material categories based on a balance between impact and data availability.
Second, we lowered the revenue threshold this year to ensure we have projects represented from a wider range of geographies and project types.
Finally, all projects will collect product-specific EPDs where available in lieu of the industry average values we used in the 2022 baseline.
Built: Although I realize you can’t improve what you don’t measure, the next question has to be how to reduce embodied carbon. Thoughts?
Parris: There’s no getting around the urgency. Turner is collaborating with clients, designers and suppliers to encourage low-carbon products and has actively managed embodied carbon on over 75 projects in addition to our benchmarking efforts.
Built: Is Turner’s ultimate goal to reach absolute zero on carbon emissions, including embodied carbon? Any projections on when?
Parris: Turner has committed to net zero scope 1, 2 and 3 emissions (including embodied carbon) by 2040, with interim targets for net zero scope 1 and 2 by 2030. The work we’re doing to engage our supply chain is integral to making absolute zero a realistic ultimate goal.