The U.S. Dept. of Energy has issued its first  definition of what it means to be a zero-energy building, and buildings-related organizations say that it should provide consistency and clarity for the construction industry.

The U.S. Dept. of Energy has issued its first  definition of what it means to be a zero-energy building, and buildings-related organizations say that it should provide consistency and clarity for the construction industry.

DOE's "Common Definition of Zero Energy Buildings," released on Sept. 17, says a zero- energy facility is "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." The definition also applies to campuses, portfolios and communities. It provides measurement and implementation guidelines and explains how to use the definition for buildings projects.

According to the New Buildings Institute, the number of zero-energy buildings doubled between 2012 and 2014 across 36 states. As that number has grown, however, so has confusion on key definitions related to net-zero buildings,  underscoring the need for DOE to develop a  commonly accepted definition and approach.

Over the past 18 months, DOE worked with groups such as the American Institute of Architects, the U.S. Green Building Council, the National Institute of Building Sciences (NIBS) and the American Society of Heating, Refrigerating and Air-Conditioning Engineers to develop the definition. "NIBS and DOE have created a set of clear and concise definitions for zero-energy buildings that will help to narrow the broad array of terminology currently used in the industry," New Buildings Institute CEO Ralph DiNola said.