2021 IECC (Base Codes)

Codes And Policy / Energy Codes

Updates to the 2021 International Energy Conservation Code (IECC) are currently underway. NBI is drawing on deep experience in advanced energy code implementation in cities and states, as well as past success in the IECC process to achieve a 10%-15% efficiency improvement.

NBI along with a broad group of partners has developed roughly 30 code proposals that if adopted will improve energy efficiency in the IECC and put us on a glide path to lower energy costs and higher property values, better comfort and productivity, and lower carbon emissions from buildings.  Watch the on demand webinar from March 5, 2019 that explains the IECC process and proposed changes, which fall into the following four broad themes:

Flexibility. These proposals advance the flexibility of both the commercial and residential parts of the energy code and allow the code to improve the energy efficiency of buildings without adopting requirements that are not appropriate for all projects. By including multiple options that may be highly effective in some situations but not in others, the code can offer increasing energy efficiency while providing projects flexibility to choose the path to efficiency that works best for that project. This is at the heart of Section C406 in the commercial section of the energy code.

Flexibility for the Future


Ready & Resilient. These proposals augment the code to ensure that buildings are ready for a future of greater resiliency and zero energy performance. They update existing requirements and definitions to align them with current market and policy trends and introduce new requirements to ensure that buildings built today can adapt to these emerging trends.

Ready & Resiliant


Commercial. These proposals cover a wide range of issues and improve the commercial section of the IECC by adding additional efficiency, clarifying requirements and creating greater flexibility for code users and local jurisdictions.



Residential. These proposals cover a wide range of issues and improve the residential section of the IECC by adding additional efficiency, clarifying requirements and creating greater flexibility for code users and local jurisdictions.


Want to get involved? Register to vote!

If you work for a state or local government, you may be eligible to vote on the final code proposals. While that voting won’t happen until November, there are steps you need to take now. The Path for Participation in the 2021 IECC Code Cyclemost important thing is make sure your agency, department, or unit is a member of the International Code Council (ICC). The deadline for registration is March 29. If you’re not a member by then, you won’t be able to vote on proposals for the 2021 IECC. See the table for a schedule of the IECC development process. or visit our IECC Voting page to learn more.

IECC Voting


More about the IECC and benefits of improved efficiency

The IECC is the most widely adopted energy code by local jurisdictions in the United States. It provides many benefits, among which is the model code development process that offers an international forum for energy professionals to discuss performance and prescriptive code requirements. This model code also encourages international consistency in the application of provisions. Boosting the efficiency of building energy codes is essential to sound energy policy and to meeting Paris Accord and other carbon reduction targets. Buildings use over 40% of the energy used in the United States, including 70% of the electricity. Building energy use accounts for more than one-third of greenhouse gas emissions globally. Improvements to the new and existing building stock are critical to reducing energy use and meeting climate goals.

The IECC is updated every three years through a stakeholder approval process. While progress was made in efficiency gains in this code between 2006 and 2012, more recently efficiency improvements have stagnated due to political pressure from specific interest groups, leaving many jurisdictions unable to move forward with efficiency gains. The 2021 IECC is the best near-term opportunity to curb carbon impacts from new buildings across the United States.