Buildings and their construction account for around 40% of all carbon emissions today. Half those emissions come from the construction alone, so buildings successfully powered by clean energy won’t come close to fixing the whole problem. John Matson and Rebecca Esau at RMI describe how industry leaders are creating the tools to measure and gather data on the “embodied carbon” in building materials (concrete, rebar, glazing, insulation, other steel), and make them freely available so the problem is transparently quantifiable – an essential first step. The authors quote research that says as much as 46% of this embodied carbon can be slashed at little to no cost (less than 0.5% of the total project cost).
So once visibility of the carbon is established, customers have little excuse to do nothing about it. The goal is for embodied carbon to become a key metric of building performance. It can then become a deal-breaker over what gets bought and what gets built, as industry leaders and policymakers use their influence and purchasing power to reshape the marketplace. Once wide-scale adoption of low-carbon materials makes them price-competitive, they will become the norm. The sector has done it before: it’s the way low-VOC paints and lead-free materials have now become the standard.
The building of the future doesn’t burn natural gas or use coal-powered electricity. It harnesses renewable electricity, efficiency, clean heat, energy storage, and other technologies to keep the lights on and keep occupants comfortable without putting any more planet-warming carbon dioxide into the atmosphere.
But even if that clean-running building of the future were erected today, its construction would still generate plenty of CO2—much of it from the production of concrete, steel, and other materials. This often overlooked source of carbon can account for more than half of a new building’s lifetime emissions, according to a report from the World Business Council for Sustainable Development and the design and engineering firm Arup.
“As we’ve gotten better and better at reducing operational energy use, it’s made it very clear that there’s this whole other chunk of the problem,” says Scott Schneider, a principal at the engineering firm Thornton Tomasetti. Now, leading industry players are taking aim at this carbon “embodied” in the built environment—and finding that small changes can yield outsized results in a sector that accounts for almost 40 percent of carbon emissions today.
Raising the bar
In recent months, major firms including Arup and the construction and development firm Skanska USA have announced new commitments to measure or collect estimates of the embodied carbon in their portion of building projects. Those measurements are a necessary first step to build awareness of low-carbon alternatives and steer the buildings sector toward a net-zero future. “Everyone has design rules of thumb that they’ve built up over years of experience,” says Erin McConahey, a principal at Arup. “In embodied carbon, nobody has any of that intuition.”
The new commitments add to growing momentum within the industry, as firms and professional societies begin to lay the foundation for a truly carbon-neutral built environment. The SE 2050 Commitment, an initiative launched in 2020, challenges structural engineers to eliminate embodied carbon in their projects by 2050. Firms including Thornton Tomasetti, Arup, and Walter P. Moore have signed on to the commitment and submitted action plans outlining how they will get there.
Policymakers are taking note, too. Marin County, California, enacted a low-carbon concrete building code in 2020. Concrete and cement are frequent targets for emissions cuts, as cement production currently accounts for 8 percent of global CO2 emissions. New York passed a law last year to tilt state procurement contracts toward low-carbon concrete. Colorado also passed “Buy Clean” legislation in 2021 to help drive the use of low-carbon materials in state-funded projects. The Biden administration recently announced its own “Buy Clean” initiative for federal purchasing, and several states are considering their own legislation.
Up to 46% of embodied carbon can be slashed at little to no cost
Although building materials account for a large share of greenhouse gas emissions, shining a light on this underappreciated problem reveals opportunities for steep reductions. In announcing its decision to invest in assessing the embodied carbon of new construction projects, Skanska cited research that came out of its partnership with RMI that showed that as much as 46 percent of embodied carbon can be slashed at little to no cost.
This article was first published on RMI.org