The U.S. Department of Energy released a common definition of a zero energy (or net zero energy) building, stating it is an “energy-efficient building where, on a source energy basis, the actual annual delivered energy is less than or equal to the onsite renewable exported energy.” In other words, it produces enough renewable energy to meet its own annual energy consumption requirements, thereby reducing the use of non-renewable energy in the building sector. This definition also applies to campuses, portfolios and communities. For guidelines on zero energy measurement and implementation, visit