After receiving public input, the Biden administration has revealed the highly anticipated, finalized version of its National Definition of a Zero Emissions Building. According to the U.S. Department of Energy (DOE), the standardized definition will help advance industry efforts to decarbonize the buildings sector, which is responsible for more than one-third of total U.S. greenhouse gas (GHG) emissions.
U.S. Energy Secretary Jennifer M. Granholm said, “With today’s announcement, DOE is helping bring clarity to our public- and private-sector partners to support decarbonization efforts and drive investment—paving the way for the cutting-edge clean energy technologies we need to make America’s buildings more comfortable and affordable.”
Notably, the national definition is not a regulatory standard; it is intended to provide industry guidance on what constitutes a zero-emissions building and establish consistent, measurable minimum criteria. According to the DOE, several green building organizations plan to embed the definition within their certifications. Groups including the U.S. Green Building Council (USGBC) and the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) have applauded the new national definition.
Criteria
The finalized definition is considered Part 1 and focuses on operating emissions. It applies to existing buildings and new construction of non-federally owned buildings. Future parts of the national definition will likely address emissions from embodied carbon, refrigerant, and other key elements.
At a minimum, a building that achieves zero operational emissions from energy use must be:
1. Energy Efficient
At a minimum, an existing building must satisfy one of the following criteria:
- The building obtains an ENERGY STAR score of 75 or higher;
- If the building is ineligible for an ENERGY STAR score, the whole building’s site energy use intensity (EUI) is at least 35% better than the median EUI for buildings of that category; or
- The whole building’s EUI is less than the EUI specified in the latest version of ANSI/ASHRAE/IES Standard 100, “Energy and Emissions Building Performance Standard for Existing Buildings,” for buildings of that type and location.
At a minimum, a new building must satisfy one of the following criteria:
- Estimated whole building energy use, reflecting as-built condition, is at least 10% lower than the model code;
- Designed to achieve an ENERGY STAR score of 90 or higher (for buildings eligible for the ENERGY STAR score); or
- Certified to the most recent effective version of the ENERGY STAR Residential New Construction program or Zero Energy Ready Homes program.
2. Free of On-Site Emissions from Energy Use
Direct GHG emissions from energy use must equal zero. There is an exception for use of emergency backup generators when grid power is unavailable.
3. Powered Solely from Clean Energy
All energy used by the building must be clean energy, obtained through any combination of on- and off-site sources, as long as the GHG emissions from that clean energy equals zero. If the building obtains heating or cooling from a district energy system, the district energy must be generated from clean sources. On-site clean energy is encouraged to be maximized before procuring off-site clean energy.
To qualify as clean energy, each source of off-site power generation for the building must meet at least one of the following requirements:
- ANSI/ASHRAE Standard 228, “Standard Method of Evaluating Zero Net Energy and Zero Net Carbon Building Performance,” Sections 8.3 to 8.5;
- Partnership Requirements for the U.S. Environmental Protection Agency’s (EPA) Green Power Partnership;
- “Green-e Renewable Energy Standard for Canada and the United States” (surplus to regulation if applicable); or
- Sections 4.2.4 to 4.2.7 of “Implementing Instructions for Executive Order 14057” on federal sustainability.
The full Part 1 definition is available here.
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