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Setting Carbon Footprint Rules for Concrete

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A new “product category rule” for concrete outlines how to conduct a life-cycle assessment and develop an environmental product declaration, practices called for by Architecture 2030 and LEED v4.

Photo: Tony Hisgett

By Nadav Malin

“When it comes to building products, reducing the carbon footprint from concrete is one of the most significant actions that the building sector can take,” says Ed Mazria, founder and CEO of Architecture 2030. While there are many ways to reduce that footprint, without clear rules defining how to measure the impacts, it’s tricky to track progress or provide incentives. Carbon Leadership Forum’s new “product category rule” (PCR) for concrete will help.

“There is a real opportunity for improving the carbon footprint of concrete through mix design,” says Kate Simonen, AIA, assistant professor in the Architecture Department at the University of Washington and director of the Carbon Leadership Forum. “Concrete is both a material with significant global impact and one that can be customized without re-tooling a factory,” Simonen explains. When environmental performance is called out as a consideration, she notes, suppliers can readily customize mixes to reduce impacts (see “Reducing Environmental Impacts of Cement and Concrete,” EBN Sept. 2010).

The demand for clear rules to govern environmental product reporting reached critical mass in 2011, with Architecture 2030 calling for the creation of a baseline carbon footprint for building materials and LEED v4 proposing credits that reward environmental product declarations (EPDs). The product category rule (PCR) that Carbon Leadership Forum is developing dictates how to perform a life-cycle assessment and create an EPD with enough specificity that it should be possible to compare EPDs from different suppliers. It also allows for “single-issue reporting” to support the carbon reduction targets of the 2030 Challenge for Products from Architecture 2030. The National Ready-Mixed Concrete Association (NRMCA) has been supporting the effort and intends to become an “EPD program operator” once the PCR is finalized, according to Lionel Lemay, senior vice president for sustainable development. As a program operator, it will provide third-party verification of EPDs.

“We’re looking to model best practices and address key opportunities and limitations of life-cycle assessments and EPDs,” notes Simonen. They chose to work first on a PCR for concrete because of the enormous opportunity for carbon reductions and because creating rules for it is especially challenging, given the variability. “There are literally millions of products; every plant has thousands of mix designs,” explains Lemay. So in addition to all the standard issues an EPD has to resolve, this one has to define a streamlined approach that allows for a range of similar mixes to be covered by one EPD.


Building industry support

Phil Williams, vice president of construction company Webcor in San Francisco, has been documenting the carbon footprint of its operations and is excited about how these rules could help bring some consistency to the Wild West of carbon reporting. “If steel, concrete, and wood each had different rules for calculating structural strength, structural engineers would have a very hard time assessing the right material for each application,” he notes. Webcor’s carbon accounting tracks 99.6% of emissions to its supply chain and only 0.4% to its own operations. “There’s nothing wrong with two-sided copying and carbon offsets for airplane flights,” he says, “but those aren’t where the big impacts are.”

Frances Yang, structural engineer with Arup in San Francisco, has been pleased with the results. There was strong interest among engineers and concrete suppliers in taking this step, she notes, because proposed LEED v4 credits create a new opportunity for concrete to contribute to a project’s certification. In current versions of LEED (2009), points are available for the use of steel—with its default recycled content value—and wood—if it’s local or FSC-certified—that aren’t available to concrete. “We think that EPDs are the first step to getting real transparency and real information,” Yang says.

The PCR defines how to create an EPD for concrete itself, not the products made from it. Precast suppliers and construction companies that want to compare different construction methods will still have to account for their own processes to compare poured-in-place with precast, for example.

International conflicts

PCRs are supposed to be aligned globally whenever possible, but after this process was already under way, another effort was launched involving cement suppliers from all over the world but none from the U.S. The two groups have been actively working to align their draft PCRs, but some key differences remain.

David Shepherd, director of sustainable development for the U.S.-based Portland Cement Association, isn’t concerned about the competing standards, however. “There are significant differences in the way that cement and concrete are sold,” he explains, which require differences in the PCR. In the U.S., cement and supplemental cementitious materials are combined on a batch-by-batch basis at the ready-mix plant, while in Europe most cement is sold as a pre-blended mix.

Will the PCR get used?

Lemay is pragmatic about the likely reception this PCR will get in the industry. Adoption will take a while, he says, with a few industry leaders diving in right away and others signing on as they see demand from their customers. Williams agrees, noting that Webcor’s clients rarely ask for the carbon footprint data the company already collects.

Architecture 2030’s Ed Mazria intends to do his part to stir up interest: “We look forward to taking the next steps—calculating the carbon footprint of concrete mixes, setting an industry benchmark, realizing carbon reductions, and engaging architects to specify low-carbon concrete,” he said.

For more information:

Carbon Leadership Forum

Architecture 2030

National Ready-Mixed Concrete Association (NRMCA)



Comments (1)

1 Central Concrete first in US posted by Anne Banta on 11/26/2012 at 11:39 am

We are glad to be a part of this movement relative to transparency. At Greenbuild, the Carbon Leadership Forum announced standards for Concrete and Central Concrete, a U.S. Concrete Company member, was the first ready mix company in the United States to: 1. Announce that it had adopted the Architecture 2030 Pledge for Products (and had already met the 2014 target) 2. Initiate development of Environmental Product Declarations for concrete.

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October 26, 2012