Buildings that produce more energy than they consume have moved from concept to increasingly common reality in recent years. But until a few months ago, no general, industry-wide agreement existed as to what exactly defined such a building. The U.S. Department of Energy (DOE) adopted “A Common Definition for Zero Energy Buildings,”¹ a report prepared for the DOE by the National Institute of Building Sciences in September 2015, with hopes that it will spur the addition of such buildings, grow the expertise required to design and operate them, and, ultimately, make them more affordable.

The resulting common definition for a zero energy building (ZEB) also applies to a net zero energy or zero net energy building.

Zero Energy Building: An energy-efficient building where, on a source energy basis, the actual annual delivered energy is less than or equal to the on-site renewable exported energy.

Before arriving at the common definition, the Department of Energy evaluated current definitions for zero energy buildings and solicited industry input. This project expanded initial zero energy building definition efforts from the DOE and National Renewable Energy Laboratory (NREL).