New ASHRAE standard defines ‘zero energy’ and ‘zero carbon’ buildings

ASHRAE has released a new standard that defines the terms "zero Energy" and "zero carbon" to describe 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 operation. The standard draws from other ASHRAE standards 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.”

Features of Standard 228 include:

Allowances for sites that lack the means 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 including energy used or lost in extraction, generation, and transit to the site.
The main energy calculation made in terms of annual average factors. Allowance is made for the calculation of individual hours where data is available.

New York City has two very large buildings dedicated to answering the 911 calls of its five boroughs. With more than 11 million emergency calls annually, it makes perfect sense. The second of these buildings, the Public Safety Answering Center II (PSAC II) is located on a nine-acre parcel of land in the Bronx. It’s an imposing 450,000 square-foot structure—a 240-foot-wide by 240-foot-tall cube. The gleaming aluminum cube risesthe equivalent of 24 stories from behind a grassy berm, projecting the unlikely impression that it might actually be floating. Like most visually striking structures, the building has drawn as much scorn as it has admiration.