Earlier this month, the US Department of Energy (DOE) released the first National Definition of a Zero-Emissions Building. DOE intends for this definition to set forth “standardized, consistent, and measurable minimum criteria” that can be adopted by public and private entities to support the transition for buildings toward zero emissions. The release of the definition follows on the heels of DOE’s National Blueprint for the Buildings Sectors, published in April. The Blueprint sets forth actions with the aim of reducing greenhouse gas emissions from US buildings 65% by 2035 and 90% by 2050 from a 2005 baseline, with cross-cutting goals of equity, affordability, and resilience. While this definition serves only as non-binding guidance, it may influence other regulatory and industry standards as buildings move toward decarbonization.  

At this stage, DOE has released only Part I of the definition, which requires that buildings with zero operational emissions from energy use meet three criteria:

• Energy efficiency: The building must either obtain an Energy Star score of 75 or higher, have an energy use intensity that is at least 35% or better than the median intensity for buildings of that category, or have an energy use intensity less than the one specified in the ANSI/ASHRAE/IES Standard 100 for buildings of that type and location. Additionally, the building must have an energy use at least 10% below the model code, be designed to achieve an Energy Star score of 90 or higher, or be certified to meet the Energy Star Residential New Construction program or Zero Energy Ready Homes program.
• Free of on-site emissions from energy use: Direct greenhouse gas emissions from energy use must be equal to zero, with the exception of use of backup emergency generators.
• Powered solely from clean energy: All of the energy (on-site and off-site) used to power the building must be obtained from clean energy sources, meaning the energy meets the requirements of either the ANSI/ASHRAE Standard 228, the Partnership Requirements for the US Environmental Protection Agency’s Green Power Partnership, the Green-e Renewal Energy Standard for Canada and the United States, or the Implementing Instructions for Executive Order 14057.

Importantly, DOE’s definition does not provide verification standards, and the agency will not itself certify whether a building meets the criteria under this definition. Instead, where an entity employs the definition, it should determine how the criteria must be documented and verified.

This federal definition of a zero emissions building was released against the backdrop of states and municipalities taking legislative action to require or encourage building decarbonization through building performance standards which limit energy use or emissions. In Maryland, for example, a 2022 law requires covered buildings (those over 35,000 square feet) to achieve net zero greenhouse gas emissions and energy use intensity standards by 2040, with an incremental target of achieving 20% reduction in net direct greenhouse gas emissions by 2030. New York City’s Local Law 97, sets emissions limits for buildings over 25,000 square feet in New York City, which covers around 50,000 buildings and 50% of the City’s building emissions. The compliance period began in January of 2024 and there are incrementally more stringent requirements for compliance over time. While emissions limits will not require any buildings to become zero emissions in the near term, all covered buildings must demonstrate compliance with an emissions factor of zero beginning in 2050. In Massachusetts, a 2022 law requires improved building efficiency and mandatory reporting of energy usage for buildings of a certain size. This law, combined with a grant program to assist with a transition to higher performance buildings, lays the groundwork for the state to promulgate net-zero building performance standards in the future.

We may see state and local laws begin to coalesce around building performance standards incorporating the new federal definition for zero emissions buildings. Similarly, various voluntary green building certifications which often lack consistency across frameworks have agreed to align with DOE’s new definition. This includes the most commonly used LEED Certification from the US Green Building Council. Thus, this newly established federal definition of zero emissions buildings developed with input from thousands of stakeholders may drive both industry and regulators toward a more standardized framework for assessing building energy and emissions performance.

It is noteworthy that DOE’s criteria for buildings with zero operational emissions from energy use comprise only “Part I” of the definition. The guidance suggests that future parts of the definition may address considerations that fall outside the scope of operational emissions, including embodied carbon and refrigerant use. Additionally, it acknowledges the myriad factors outside of greenhouse gas emissions that could have positive climate, environmental, and health impacts from buildings, such as resiliency, walkability, healthy materials, electric vehicle support and others. Future incorporation of these types of factors into the definition have the potential to influence building design and broader development efforts over time.

Companies seeking to comply with state and local net zero requirements or making voluntary net zero claims should begin to evaluate their sustainability performance in light of DOE’s definition.