4 Big Questions as Building Codes Consider Embodied Carbon

May 11, 2023 / Building Green

A recent article by Building Green attempts to answer the question, are building codes the right place to regulate embodied carbon and how should they do it? Below are a few highlights from David Winans and Jessie Templeton, key members of the Climate Positive team at GGLO.

“If you’re going to set a maximum limit, it does seem like you have to do it initially by material,” said Winans, who has been working with NBI and others in Seattle and the state of Washington to advance action on embodied carbon reduction. He added in a follow-up email that such limits should come with “provisions that allow for weighted averaging.” Winans also observed that, although WBLCA is where the industry needs to go to “optimize carbon reduction,” many firms aren’t currently modeling buildings accurately enough to satisfy potential code requirements for WBLCA, and there’s not a “good WBLCA baseline library” for practitioners to compare designs against.

Moreover, Winans continued, “Code reviewers don’t yet have the capacity to check Revit and WBLCA models for accuracy to determine if designs do comply with any limits that are set.”

GSA and other entities are using or encouraging use of EC3, the Embodied Carbon in Construction Calculator. This free software tool gives digital access to environmental product declarations (EPDs), which include carbon footprint data alongside other information on environmental impacts. Because EPDs are based on modeled estimates—some more accurate than others—EC3 incorporates uncertainty factors into its search results and comparisons. That makes results more transparent but can also make them more confusing for new users to interpret.

And EPDs are crowdsourced from manufacturers, so “in certain categories, there’s not yet a lot of data,” said Jessie Templeton, AIA, senior associate at GGLO. She pointed specifically to enclosures and finishes. Templeton added, though, that for the categories that are well represented, EC3 is a good decision-making tool. “If you need to choose a Type X, 5/8″ gyp board, you can compare the CO2 equivalent” of multiple products, she said. “It’s really valuable.”

Having access to EC3 also “works for firms that don’t have the ability to do whole-building LCA,” Templeton continued. “We know we need to focus first on concrete, steel, and gyp board. You can use EC3 and figure out what you need to write into the spec.”

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