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Embodied carbon scrutiny plants green discipline at structural materials door

Action on cradle-to-initial occupancy carbon dioxide emissions factors, coupled with the potential for fundamental changes in project planning and procurement, qualify 2019 as a watershed in the green building movement.

Architectural, engineering and construction (AEC) community leaders are taking stands impacting cement, concrete, steel, aluminum and wood more than the U.S. Green Building Council’s LEED v4 rating system, whose 2014-2016 implementation ushered broad Environmental Product Declaration (EPD) development and release. A deep EPD library built over the past five years, plus increasingly sophisticated methods of gathering and validating material or product environmental metrics, will empower design professionals who are personally concerned with atmospheric CO2 levels or acting on behalf of carbon-minded owners or clients.

USGBC’s Greenbuild International Conference and Expo served as the backdrop for major AEC players’ push to improve CO2 emissions accounting. Staged last month in Atlanta, the event also saw the Council announce assertive measures to influence project specifications through LEED (Leadership in Energy and Environmental Design) or other channels.

A University of Washington College of Built Environments-hosted coalition of AEC stakeholders, the Carbon Leadership Forum (CLF) formally unveiled the Embodied Carbon in Construction Calculator (EC3) tool in public beta version at Greenbuild. Embodied carbon (EC) volumes reflect CO2 emissions attributable to material or product processing, fabrication, delivery and erection or placement. The open-access EC3 taps the industry’s first database of digitized EPD whereby architects, engineers, owners, contractors, building material suppliers and policy makers can easily evaluate EC in project specifications. “The Forum and nearly 50 industry leaders committed to a tool that was free to use and part of a growing open-access embodied carbon data ecosystem,” notes CLF Director Kate Simonen.

In tandem with EC3, global engineer Thornton Tomasetti previewed Beacon, a free EC measurement and optimization tool set for release by year’s end (note “Engineer validates foundation, beam, column, slab embodied carbon,” page 21). Beacon user data will deepen a body of knowledge the New York-based firm gathered in a seven-year probe of higher EC materials, structural components and facility types. Analyzing figures from more than 600 buildings, Thornton Tomasetti researchers detect a market-driven trend toward increased use of supplementary cementitious materials and recycled steel as the largest driver of EC reduction much of this past decade. They also find concrete structures exhibit lower EC levels than those of steel design, and that voided slabs or hollow core plank reduce EC in elevated floors—the points of highest EC levels in typical buildings. Beacon programming goes hand in hand with Thornton Tomasetti’s embrace of the CLF Structural Engineers 2050 Challenge. In the tradition of the American Institute of Architects-aligned 2030 Challenge for Buildings, SE 2050 prompts structural engineers to provide measurements of progress toward a vision of zero carbon buildings by mid century.

If EC3 and Beacon weren’t enough for Greenbuild 2019, USGBC weighed in with the launch of LEED Positive, mapping energy and carbon reduction targets that will “require new construction to go farther and push existing buildings with high consumption to substantially increase their efficiency efforts.”

If the Greenbuild groundswell of EC buzz weren’t enough for an industry riding a speeding train, the opening day of the conference coincided with the Marin County (Calif.) Board of Supervisors promulgating a building code first among U.S. governing bodies: A low-carbon concrete specification, effective next month and based on CLF and National Ready Mixed Concrete Association data. A work in progress with narrow initial application, the Bay Area Low-Carbon Concrete Code (page 20) will almost certainly be emulated as public and private construction interests face an EC reckoning in 2020 and beyond.