ATLANTA — ASHRAE has released a new standard to measure zero net carbon and energy goals in buildings.

ANSI/ASHRAE Standard 228-2023, Standard Method of Evaluating Zero Net Energy and Zero Net Carbon Building Performance, sets requirements for evaluating whether a building or group of buildings meets a definition of “zero net energy” or a definition of “zero net carbon” during building operation. The standard draws from ASHRAE Standard 105, among others, to address energy and carbon flows across a site boundary, their measurement, and their balance.

“Achieving a zero energy building has been viewed by many as a difficult goal to meet, with unforeseeable roadblocks and differing guidance,” said Keith Emerson, P.E., Life Member ASHRAE, 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.”

Additional features of Standard 228 are as follows: 

• Allowances for sites that lack the opportunity to produce adequate renewable energy while placing additional requirements on the use of external carbon and renewable energy in the calculation;

• Defined calculation of energy in terms of source — a multiplier on the energy crossing the site boundary to include energy used or lost in extraction, generation, and transit to the site; and
• The main energy calculation made in terms of annual average factors. Allowance is made for the calculation of individual hours where data is available.

Standard 228 does not apply to the establishment of building energy performance goals or limits; design guidance or design requirements; embodied energy of building materials and systems; and transportation to and from a building. The standard is also not intended to circumvent any safety, health, or environmental requirements.

For more information, visit ashrae.org/228.