ASHRAE has released a new standard, ANSI/ASHRAE Standard 228-2023, which outlines the method for evaluating building performance in achieving zero net energy and zero net carbon status. The standard specifies requirements to determine if a building or group of buildings satisfies the definition of “zero net energy” or “zero net carbon” during building operation. It incorporates ASHRAE Standard 105 and other sources to address the measurement, balance and flow of energy and carbon across a site boundary.

“Achieving a zero-energy building has been viewed by many as a difficult goal to meet, with unforeseeable roadblocks and differing guidance,” says Keith Emerson, chair of the Standards Project Committee 228. “Standard 228 provides a consistent method for determining whether new and existing sites have reached zero energy. We hope this standard will become a helpful resource for building professionals in strategic decarbonization planning.”

The standard also introduces allowances for sites that lack the opportunity to produce adequate renewable energy and defines the calculation of energy in terms of source, which is “a multiplier on the energy crossing the site boundary to include energy used or lost in extraction, generation and transit to the site,” per ASHRAE officials.

According to Standard 228-2023, the evaluation method for zero net energy and zero net carbon building performance does not cover the establishment of building energy performance goals or limits, design guidance or requirements, embodied energy of building materials and systems or transportation to and from a building. It should also not be used to bypass any safety, health, or environmental regulations.