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Homes and buildings continue to be among the most significant energy use sectors, accounting for approximately 41 percent of the nation’s total energy consumption, 72 percent of electricity usage, and over one-third of greenhouse gas emissions. Because homes and buildings represent such a significant portion of the nation's energy consumption, targeted policies and codes must govern the way and extent to which they use energy.

One of the best and most cost-effective ways policy can reduce energy consumption in new and existing homes and buildings is through building energy codes. Building energy codes prescribe a minimum level of energy efficiency new and existing home and building renovations must exhibit. Homes and buildings constructed to comply with the most recent energy codes use less energy, have lower operational costs, and are more resilient. Building codes also reduce carbon emissions and, with negligible upfront costs to constructing buildings to these standards, pay for themselves by providing the building owner savings on energy and maintenance costs.

As states and communities begin to address climate change by adopting aggressive goals to reduce energy use and greenhouse gas emissions, building energy codes – including related training and support structures –  become an essentail pathway. By driving higher performance building practices throughout the construction industry, building codes are influencing and ultimately defining state and local priorities toward zero energy and emissions homes and buildings.

Model Energy Codes

There are two energy codes commonly adopted by states: the International Energy Conservation Code (IECC) and the ASHRAE 90.1 Standard. States often amend and modify codes as they see fit for their state, including language that can increase efficiency, reference other standards, or to add alternative compliance pathways. To learn more, visit NEEP's Model Code Page.

Stretch Codes

To achieve even greater energy efficiency, states and communities can promulgate a voluntary or mandatory "stretch" or "reach” energy code to supplement or overlay their base code, providing communities a code option that is typically 15-20% more energy efficient than the state’s base energy code. Visit NEEP's Next Generation Home and Building Performance Page to learn more.

Massachusetts Energy Zero Code

The Massachusetts Energy-Zero (E-Z) Code is a zero energy stretch code for commercial construction. The E-Z Code offers multiple compliance pathways, renewable energy requirements, and optional jurisdictional electives. The code focuses on optimizing energy efficiency and providing a clear pathway for buildings to achieve zero energy.

Code Adoption and Compliance

Adopting energy codes is the first step – complying with and enforcing energy codes is the second and most important step. While states and communities should adopt updated energy codes, enforcing them is the only way to unlock deep energy savings. Visit NEEP's Code Adoption and Code Compliance pages to learn more.


Building energy codes represent the “floor”— the lowest level of energy efficiency homes and buildings must exhibit by law. NEEP works to raise this floor, in conjunction with its other building and community initiatives, through energy code adoption and compliance support.

We provide technical support to develop, implement, and comply with building energy codes and standards. By creating resources, providing technical assistance, hosting webinars and events, or facilitating energy code stakeholder groups, NEEP provides regional, state, and municipality-specific guidance on how to advance the energy efficiency, decarbonization, and electrification of homes and buildings through energy codes.

Today’s building codes are about 30 percent more efficient than they were ten years ago. By adopting and complying with these more efficient energy codes, states in the Northeast and Mid-Atlantic will continue to progress steadily towards a future where all new homes and buildings must meet zero energy code requirements. 


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