How Can a Building Become “Zero Carbon”?
As we grapple with the full life cycle of all materials and surfaces in a project, how we view "net zero" is set to change.
Surfaces of all kinds are top of mind these days, so we decided to look at all aspects of them, in these articles, from A to Z. Thinking of surfaces less as a product category and more as a framework, we use them as a lens for understanding the designed environment. Surfaces are sites of materials innovation, outlets for technology and science, and embodiments of standards around health and sustainability, as well as a medium for artists and researchers to explore political questions.
Net-zero ratings, which certify that a building reduces and offsets the resources it uses to the maximum extent possible, come in four flavors: carbon, energy, water, and waste. Not all of these take into account the materials and surfaces that make up the building, but as we grapple with the full life cycle of projects, that is set to change.
On carbon, the International Living Future Institute Zero Carbon certification states: “One hundred percent of the operational energy use associated with the project must be offset by new on- or off-site renewable energy. One hundred percent of the embodied carbon emissions impacts associated with the construction and materials of the project must be disclosed and offset.”
The key term here is “embodied carbon emissions,” which should account for making, transporting, and installing concrete, glass, steel, and wood, as well as the dozens of other materials in surfaces, like ceilings, floors, walls, and upholstery. In a building’s first year, these emissions can account for as much as 80 percent of the total carbon footprint.
Surely those same manufacturing processes that produce carbon emissions also use up energy and water and generate waste. Yet these “embodied” aspects are not considered at all in zero-energy and zero-water ratings, and only to some extent in zero-waste ratings. (The conventional water and energy ratings currently focus narrowly on operational resource use.)
Green Business Certification’s TRUE zero-waste program asks projects to divert 90 percent or more of their total waste from landfills, offering credits for for picking vendors who recycle products and reduce waste.
Despite the ratings’ limitations, designers who specify materials and surfaces should note that change is coming. This past January, LEED Zero announced that its carbon certification will eventually expand “to incorporate carbon caused from water consumption, waste generation, and the embodied carbon of materials.” When that happens, zero-carbon ratings will be able to truly certify, based on a holistic accounting of resources, that a building does no harm to the environment.
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