Published by Architectural Record: What do we mean when we call something “zero carbon”? Its definition is self-evident, like “gluten free” or “tax-deductible.” But does the term need a qualifier?

The contributors to a building’s carbon output can be broken down into the emissions associated with grid-delivered electricity, on-site combustion, and embodied carbon (the emissions produced by material extraction, construction, and demolition and disposal), as well as water consumption, and refrigerants, according to the New Buildings Institute (NBI). Currently, there are more than a dozen organizational definitions of what constitutes carbon-neutral building operations, all represented by a roughly equal number of standards. The ones with the most brand recognition include LEED Zero Carbon, Zero Code, and the International Living Future Institute’s (ILFI) Zero Carbon certification. Though they generally agree on the need to reduce site energy use and the importance of operational efficiency, each one paves a slightly different pathway to achieving carbon neutrality. For instance, on-site combustion is still permitted, to varying degrees, by most standards, as is the use of off-site renewables, while embodied carbon and the source of grid-delivered electricity are considered to various extents across the different programs.

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