Residential Energy Codes
Energy codes are a subset of building codes that establish minimum levels of energy efficiency when constructing a building or renovating an existing one. They can dictate specific materials and practices that must be used, or have some other system to assess energy efficiency in the building. Energy codes set standards for building materials, design, and construction practices for walls, floors, ceilings, lighting, windows, doors and other parts of a building, and they are consistently updated to reflect changes and best practices in technology and methodology. Typically, states have different energy codes for residential and commercial buildings; the code itself will specify which classes of buildings are covered.
In the U.S., states can adopt building codes in a few different ways. Some do not put forth any statewide building codes, instead choosing to implement home rule, which shifts the onus of adoption to local jurisdictions including counties and cities. Other states adopt building codes through legislative action or regulatory mandate. A majority of statewide codes are based on the International Code Council’s I-Codes and/or the ASHRAE standards — energy codes specifically are based on the International Energy Conservation Code (IECC) and ASHRAE 90.1 codes — both of which are updated on a three-year cycle. IECC model codes are most commonly adopted for residential buildings, often with state amendments, although some states will create their own codes with more stringent or more relaxed requirements.
What are I-Codes? The I-Codes are widely adopted in the United States and created by the International Code Council. These codes are created as model rules, meant to be adopted with various amendments in order to better serve each particular jurisdiction. I-Codes include the International Building Code (for commercial structures), the International Residential Code, and the International Energy Conservation Code, among others. The most current versions are the 2024 I-Codes.
What are ASHRAE Codes? ASHRAE codes are the other widely-adopted building codes in the United States, used for commercial building standards. ASHRAE 90.1, developed in 1989, established energy efficiency and performance standards for commercial buildings and has been updated regularly every three years since. This model is meant to be adopted as appropriate by states and/or local jurisdictions, and is referenced in specific sections of the I-Codes. The current version is 90.1-2022.
Key Resources
Status of Energy Code Adoption
Investing in Workforce Development and Training to Improve Energy Code Implementation
Policy Action Toolkit
Policy Explainer: Residential and and Commercial Energy Codes
Model Rules
Building Decarbonization Code
Model States
Colorado
State law requires local jurisdictions to adopt and enforce the 2021 IECC and the Colorado Model Electric Ready and Solar Ready Code upon updating any other building code between July 1, 2023 and June 30, 2026. Cities and counties with building codes must adopt the Model Low Energy and Carbon Codes, which is 2024 IECC with amendments, or a code that will achieve greater energy efficiency and emissions reductions, when they update any other building codes after July 1, 2026.
The Model Low Energy and Carbon Code: Larger homes over 7,500 square feet must achieve net-zero energy and cover all energy use with on-site renewable options, such as solar panels or a community solar garden. Homes under 5,000 square feet must meet base-level efficiency standards, and homes between 5,000 and 7,499 square feet must meet more stringent efficiency standards. The code also encourages heat pump adoption.
Illinois
The statewide energy code for residential construction is 2024 IECC with amendments.
Rhode Island
The statewide energy code for residential construction is 2024 IECC with amendments.
Washington
The statewide energy code for residential construction is the Washington State 2021 Energy Code.
Residential Energy Codes By State
| Status | State Sort descending | Region | Components | Year Enacted | |
|---|---|---|---|---|---|
| Enacted |
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The statewide energy code for residential construction is 2015 IECC with amendments. Alabama Residential Building Code Advisory Council was tasked with recommending an energy code for adoption by the Home Builders Licensure Board by October 2025. The Board has not adopted a new code. Establishing Policies
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|
Southeast | 2016 | ||
| Not Enacted |
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Alaska does not have a statewide energy code, but the Alaska Housing Building Energy Efficiency Standard (BEES) applies to construction where state financial assistance is used for a loan. BEES is currently comprised of the 2018 IECC, ASHRAE 62.2 2016, and Alaska Specific Amendments to both. Establishing Policies
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|
West | |||
| Not Enacted |
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Residential energy codes are statewide building codes that dictate the energy performance requirements of newly constructed residential buildings. Empty column
|
Southwest | |||
| Enacted |
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The statewide energy code for residential construction is 2009 IECC. Establishing Policies
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|
Southeast | 2014 | ||
| Enacted |
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The statewide energy code for residential construction is the California 2025 Energy Code. AB 130 (2025) has established a six-year pause (October 2025–June 2031) on new residential building code updates. Establishing Policies
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|
West | 2025 | ||
| Enacted |
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State law requires local jurisdictions to adopt and enforce the 2021 IECC and the Colorado Model Electric Ready and Solar Ready Code upon updating any other building code between July 1, 2023 and June 30, 2026. Cities and counties with building codes must adopt the Model Low Energy and Carbon Codes, which is 2024 IECC with amendments, or a code that will achieve greater energy efficiency and emissions reductions, when they update any other building codes after July 1, 2026. The Model Low Energy and Carbon Code: Larger homes over 7,500 square feet must achieve net-zero energy and cover all energy use with on-site renewable options, such as solar panels or a community solar garden. Homes under 5,000 square feet must meet base-level efficiency standards, and homes between 5,000 and 7,499 square feet must meet more stringent efficiency standards. The code also encourages heat pump adoption. Establishing Policies
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|
West | 2025 | ||
| Enacted |
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The statewide energy code for residential construction is 2021 IECC with amendments. Establishing Policies
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|
Northeast | 2022 | ||
| Enacted |
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The statewide energy code for residential construction is 2018 IECC. The Delaware Energy Office must review the State Energy Code triennially for potential updates to the IECC and ASHRAE energy codes. Establishing Policies
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|
Southeast | 2020 | ||
| Enacted |
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The statewide energy code for residential construction is 2021 IECC with amendments. Establishing Policies
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|
Southeast | 2023 | ||
| Enacted |
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The statewide energy code for residential construction is 2015 IECC with amendments. Establishing Policies
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|
Southeast | 2023 | ||
| Enacted |
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The statewide energy code for residential construction is 2018 IECC with amendments. Establishing Policies
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|
West | 2021 | ||
| Enacted |
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The statewide energy code for residential construction is 2018 IECC with amendments. Establishing Policies
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|
West | 2020 | ||
| Enacted |
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The statewide energy code for residential construction is 2024 IECC with amendments. Establishing Policies
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|
Midwest | 2025 | ||
| Enacted |
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The statewide energy code for residential construction is 2018 IECC. Establishing Policies
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|
Midwest | 2019 | ||
| Enacted |
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The statewide energy code for residential construction is 2012 IECC with amendments. Establishing Policies
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|
Midwest | 2014 | ||
| Not Enacted |
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Residential energy codes are statewide building codes that dictate the energy performance requirements of newly constructed residential buildings. Empty column
|
Midwest | |||
| Enacted |
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The statewide energy code for residential construction is IECC 2009 with amendments. Establishing Policies
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|
Southeast | 2014 | ||
| Enacted |
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The statewide energy code for residential construction is 2021 IECC with amendments. Establishing Policies
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|
Southeast | 2022 | ||
| Enacted |
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The statewide energy code for residential construction is 2021 IECC. Establishing Policies
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|
Northeast | 2024 | ||
| Enacted |
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The statewide energy code for residential construction is 2021 IECC with amendments. Establishing Policies
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|
Southeast | 2023 | ||
| Enacted |
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The statewide energy code for residential construction is 2021 IECC. Establishing Policies
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|
Northeast | 2022 | ||
| Enacted |
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The statewide energy code for residential construction is 2015 IECC with amendments. Establishing Policies
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|
Midwest | 2025 | ||
| Enacted |
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The statewide energy code for residential construction is 2012 IECC with amendments. Establishing Policies
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|
Midwest | 2014 | ||
| Not Enacted |
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Residential energy codes are statewide building codes that dictate the energy performance requirements of newly constructed residential buildings. Empty column
|
Southeast | |||
| Not Enacted |
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Residential energy codes are statewide building codes that dictate the energy performance requirements of newly constructed residential buildings. Empty column
|
Midwest | |||
| Enacted |
Empty column
The statewide energy code for residential construction is 2021 IECC with amendments. Establishing Policies
Empty column
|
West | 2022 | ||
| Enacted |
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The statewide energy code for residential construction is 2018 IECC. Establishing Policies
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|
Midwest | 2019 | ||
| Enacted |
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The statewide energy code for residential construction is 2024 IECC. Establishing Policies
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|
West | 2024 | ||
| Enacted |
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The statewide energy code for residential construction is 2018 IECC. Establishing Policies
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|
Northeast | 2022 | ||
| Enacted |
Empty column
The statewide energy code for residential construction is 2021 IECC. Establishing Policies
Empty column
|
Northeast | 2022 | ||
| Enacted |
Empty column
The statewide energy code for residential construction is 2021 IECC with amendments. Establishing Policies
Empty column
|
Southwest | 2024 | ||
| Enacted |
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The statewide energy code for residential construction is the 2025 Energy Conservation Construction Code of New York State, based on 2024 IECC. Establishing Policies
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|
Northeast | 2025 | ||
| Enacted |
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The statewide energy code for residential construction is 2015 IECC. Establishing Policies
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|
Southeast | 2018 | ||
| Not Enacted |
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Residential energy codes are statewide building codes that dictate the energy performance requirements of newly constructed residential buildings. Empty column
|
Midwest | |||
| Enacted |
Empty column
The statewide energy code for residential construction is 2018 IECC with amendments. Establishing Policies
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|
Midwest | 2018 | ||
| Enacted |
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The statewide energy code for residential construction is 2018 IRC with amendments aligning with 2018 IECC. Establishing Policies
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|
Southwest | 2022 | ||
| Enacted |
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The statewide energy code for residential construction is the Oregon 2023 Residential Specialty Code, based on the 2021 International Residential Code. Establishing Policies
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|
West | 2023 | ||
| Enacted |
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The statewide energy code for residential construction is 2021 IECC. Establishing Policies
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|
Northeast | 2025 | ||
| Enacted |
Empty column
The statewide energy code for residential construction is 2024 IECC with amendments. Establishing Policies
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|
Northeast | 2025 | ||
| Enacted |
Empty column
The statewide energy code for residential construction is 2009 IECC. Establishing Policies
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|
Southeast | 2012 | ||
| Enacted |
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The statewide energy code for residential construction is 2009 IECC. Establishing Policies
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|
Midwest | 2011 | ||
| Enacted |
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The statewide energy code for residential construction is 2018 IECC with amendments. Establishing Policies
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|
Southeast | 2020 | ||
| Enacted |
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The statewide energy code for residential construction is 2015 IECC. Establishing Policies
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|
Southwest | 2015 | ||
| Enacted |
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The statewide energy code for residential construction is 2021 IECC with amendments. Establishing Policies
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|
West | 2024 | ||
| Enacted |
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The statewide energy code for residential construction is the Vermont 2020 Residential Building Energy Standards (RBES), based on the 2018 IECC. In September 2025, Governor Scott issued an executive order that reinstated the 2020 building code, making the 2024 RBES, which is based on the 2021 IECC, voluntary. Establishing Policies
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|
Northeast | 2025 | ||
| Enacted |
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The statewide energy code for residential construction is 2021 IECC with amendments. Establishing Policies
Empty column
|
Southeast | 2023 | ||
| Enacted |
Empty column
The statewide energy code for residential construction is the Washington State 2021 Energy Code. Establishing Policies
Empty column
|
West | 2024 | ||
| Enacted |
Empty column
The statewide energy code for residential construction is 2015 IECC with amendments. Establishing Policies
Empty column
|
Southeast | 2022 | ||
| Enacted |
Empty column
The statewide energy code for residential construction is 2009 IECC with amendments. Establishing Policies
Empty column
|
Midwest | 2015 | ||
| Not Enacted |
Empty column
Residential energy codes are statewide building codes that dictate the energy performance requirements of newly constructed residential buildings. Empty column
|
West |