The growing importance of embodied carbon
by Elizabeth Beardsley, senior policy counsel, U.S Green Building Council
Embodied carbon is not just a buzzword – it is increasingly recognized as an important component of greenhouse gas reduction within construction. Anyone in the supply chain of building materials and products, professionals who spec such projects and building owners and tenants need to understand what this is and how policies and other market mechanisms are driving to reduce it.
Embodied carbon refers to the amount of green- house gas emissions associated with a product or material over its life cycle. For example, a manufactured flooring product would produce greenhouse gas emissions as a result of the extraction and transportation of raw materials to the factory; use of energy and water during the manufacturing of the product; transportation of the final product to wholesale, retail, the construction site, etc.; transportation and disposal or recycling of waste and packaging; use of energy and other materials during installation of the product; and end-of-life transportation and disposal. Typically, the greenhouse gas emissions are expressed as carbon dioxide equivalents, hence “embodied carbon.”
Embodied carbon in materials and products has been on the radar for a few decades but is gaining renewed attention in light of urgent climate change predictions, such as the 1.5-degree report from the Intergovernmental Panel on Climate Change, which calls for faster immediate emission reductions to limit the cumulative atmospheric carbon. For buildings being newly constructed, the carbon emitted during this critical near term of 10 to 20 years will mostly come from materials and the construction phase, which occurs all at once, rather than operations, for which carbon is spread over the life of the building.
Tools and certifications
The LEED green building certification, created by the U.S. Green Building Council (USGBC), has incorporated life cycle thinking for building product selection for about a decade. Under the latest version of the rating system, LEED v4.1, projects can earn points for whole building Life Cycle Assessment (LCA), and additional points based on the carbon reduction achieved. Other certifications, such as those offered by organizations like Cradle to Cradle and Global GreenTag, also incorporate LCA and greenhouse gas considerations.
Nonetheless, it isn’t necessarily easy for project teams to find products they need with these kinds of disclosures or certifications, nor to sort through the data for comparable products to inform selection. New resources are emerging to help address this challenge, for example, the online Transparency Catalog, which provides a searchable database of products – including flooring – with EPDs and certifications.
Policy responses continue to develop
Governments are starting to use policies to address building materials and products’ contribution to carbon emissions. Several European countries have led the way in incorporating EPDs (France) and with requirements to meet whole building LCA targets for both public (Switzerland) and private buildings (the Netherlands).
In the U.S., Minnesota has the only mandate for embodied carbon comparison with its B3 guidelines for public projects. A whole building LCA is required and must demonstrate carbon reduction of the building’s construction materials “through building massing, structural design, dematerialization and alternative assembly and material selection.” This policy is part of state efforts for all state construction to be carbon neutral by 2030.
California enacted the Buy Clean California Act in 2017. Under this law, the agency responsible for state buildings will establish caps on embodied carbon of several structural materials. These caps will be applied, with some limitations, to public procurement using EPDs. Similar bills have been introduced in other states. This approach could eventually expand to other building materials, but even if policy stays focused on the building’s structural mass, it will likely have spillover effects to design teams and owners.
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