As we continue to look for solutions to the climate crisis, one opportunity is hidden in plain sight: decarbonization through building energy codes. Buildings make up approximately 40 percent of total global greenhouse gas emissions and advancing building codes to address decarbonization could be an extremely important piece of the emissions reduction puzzle. Let’s break down some examples in the NEEP region and beyond for opportunities to reduce emissions through building energy codes.            

Operational and Embodied Carbon

The traditional approach to efficient building design fails to consider energy consumed before and after the construction process, such as the energy used to create and transport the construction materials, which is referred to as embodied carbon. Energy codes also do not consider what happens to the building after its useful life.

In recent years, the sustainable construction and design industry has started to shift its focus and prioritize the life cycle of buildings. For example, Vermont is in the process of drafting a stretch code that addresses the global warming potential of insulation materials,[1] and is the first state in the region to consider embodied carbon in building energy codes.

Traditional energy codes also fail to address emissions associated with building occupancy, referred to as operational carbon. Current energy codes only decrease future energy use of a building through energy efficient design practices, which doesn’t look at the bigger picture. Energy codes should require jurisdictions to engage in long-term planning and track metrics that would help them to eliminate operational carbon over time.

To date, no national model energy code has included provisions relating to operational carbon, but for existing buildings, building performance standards (BPS) are starting to address operational carbon by including declining energy and emissions targets which requires actions to reduce emissions such as installing more efficient equipment when a system is replaced. Although this is a step in the right direction, new buildings should also be prepared to phase out emissions, and energy codes present a massive opportunity to kickstart this planning.  

Electric, Solar, and Electric Vehicle (EV) Readiness

Another important step to address decarbonization in energy codes is “electric readiness”, which is essentially prewiring a home to accommodate the future installation of electric equipment. This could apply to appliances that often use fossil fuels, such as ovens, clothes dryers, water heaters, and heating equipment. There should also be additional consideration for “solar readiness”, which is preparing a building to accommodate future solar system installation, as well as “EV readiness” which is having a dedicated circuit for the installation of a future electric vehicle charging.

The Rocky Mountain Institute recently found that it is three times cheaper to install electric vehicle ready measures during the construction of a new home than to retrofit the home down the line. These provisions make the transition from gas to electric easier and less burdensome so that new homeowners don’t have to absorb these costs. The first draft of the 2024 International Energy Conservation Code (IECC) for residential buildings incorporates electric ready provisions into the code,[2] but this is subject to change in the final version.[3] In addition, Massachusetts’s new Specialized Opt-In Code requires electric readiness provisions for buildings using fossil fuels for space heating.[4]          

Fossil Fuel Bans       

Some jurisdictions may want to go further and implement a ban on fossil fuel combustion in new buildings. Massachusetts is preparing to implement a pilot program for 10 communities that requires new construction or major renovation projects be “fossil fuel free”. In addition, Washington D.C. has voted to ban natural gas in new construction by 2026 and require buildings to be net zero. Governor Kathy Hochul recently proposed a ban on natural gas in new buildings in New YorkWashington state is also the first in the nation to require heat pumps in new homes.[5] The first draft of the 2024 IECC also includes an appendix that provides model code language for “all-electric residential buildings” [6], which prohibits combustion equipment in new construction. 

Municipal Action

Where allowed, municipalities in some jurisdictions may want to go beyond state code requirements through either local zoning or codes more stringent than base codes.

Municipalities in some jurisdictions have adopted stretch codes, which can provide significant energy savings compared to their state’s model energy code. Other states have developed a stretch code that is available statewide for municipal adoption, which provides consistency from town to town.

Municipalities taking the lead on these initiatives can result in further energy savings that continue to drive the mission of decarbonization.

For example, in Maryland, both Howard and Montgomery County voted to pass electrification ordinances, which are intended to require all electric construction for the county.

Federal Incentive Opportunities

Through the Bipartisan Infrastructure Law (BIL) and Inflation Reduction Act (IRA), there is a historic level of federal funds available for energy efficiency initiatives, which include incentive programs for homes that exceed energy code requirements. The 45L Tax Credit has been extended through 2032 which requires homes to comply with the Department of Energy Zero Energy Ready Homes Program. In addition, there is $225 million available over five years through the BIL to support adopting updated energy codes, as well as $1 billion available through the IRA to adopt zero net energy stretch codes and adopting the most recent model code of IECC 2021 for residential buildings and the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) 90.1-2019 standard for commercial buildings. These federal dollars will significantly impact code adoption and will drive jurisdictions to decarbonize through energy codes.

Model Codes and Decarbonization

In a blog post by Michael Waite with the American Council for an Energy-Efficient Economy (ACEEE) titled “Rethinking Model Energy Codes for Net Zero Carbon Buildings” several ideas are proposed to achieve net zero carbon model codes, including efficiency of the building envelope, using heat pumps to electrify space conditioning, flexibility in how buildings achieve emission reductions, and offsetting remaining emissions with renewables and embodied carbon. These measures should be prioritized in future model energy code development cycles to achieve advanced energy savings.    

What About Existing Buildings?

Decarbonizing existing buildings is one of the greatest challenges when it comes to energy codes. Codes can only go so far to impact existing buildings because the code is only triggered when there a building undergoes a substantial addition, alteration, or change of use. The 2024 IECC draft incorporates additional efficiency measures that are required for existing buildings,[7] but this is only applicable when the code is used. There are opportunities available outside of the energy code that could decarbonize existing buildings, such as the federal Weatherization Assistance Program, which will have additional funding through the BIL and IRA, as well as implementing more stringent building performance standards that are designed to reduce emissions.     


Emissions reductions through energy codes are hidden in plain sight. It’s a strategy to combat climate change that is often overlooked but can have an enormous impact. There are important steps to decarbonizing buildings through energy code development. They include addressing operational and embodied carbon; becoming solar, EV, and electric ready; banning combustion equipment; having municipalities take the lead; capitalizing on federal funding; addressing model codes; and supporting existing buildings decarbonization.

[1] Vermont Residential Building Energy Standards (RBES) Section R408 Insulation Embodied Carbon Emissions

[2] 2024 IECC Residential Draft Section R404.5, R404.6, and R404.7

[3] All provisions of the 2024 IECC are currently under review by the consensus committees and are subject to change. This information is based on the draft published on 12/26/2022. A final draft of the 2024 IECC is expected in late 2023. 

[4] MA Municipal Opt-In Specialized Code Sections RC104.3, RC104.4 and RC104.5

[5] Washington State Energy Code 2021 Edition Section R403.5.7 and Section R403.13

[6] 2024 IECC Residential Draft Appendix RE

[7] 2024 IECC Residential Draft Section R506

Stay informed

Stay up to date with the latest NEEP and industry news, policies, and trends to your inbox every so often.