Residential Codes

Arizona is a home-rule state, meaning that codes are adopted and enforced on a local rather than state level. However, the Southwest Energy Efficiency Project has found that the majority of new construction activity occurs in jurisdictions who have adopted the 2012 IECC or 2018 IECC.

Last Reviewed: November 2024

In 2021, the CEC adopted the 2022 Energy Code with an effective date of January 1, 2023. California moved decisively in the direction of emphasizing building decarbonization in the 2022 Energy Code. Since their inception in 1978, California’s energy standards have been fundamentally performance standards, establishing energy budgets for buildings of all types. In addition, the Energy Code provides an alternative pathway for compliance through meeting prescriptive requirements reducing energy consumption and managing building energy loads to help maintain electrical grid reliability (Public Resources Code section 25402). The 2022 Energy Code helps accomplish California’s mandate for a 100% clean energy grid and carbon-neutrality by 2045. The CEC set in place two strong energy metrics, a revisited Time Dependent Valuation metric (system energy cost metric), and a new long-term, hourly, marginal Source Energy metric (system energy metric). For single family residential buildings, the code establishes new baselines for building performance and prescriptive compliance to use heat pumps for either space or water heating. For multi-family buildings the 2022 amendments set performance and prescriptive baselines to use heat pumps for space heating. The 2022 Energy Code also established first-in-the-nation requirements for installing both solar photovoltaic and battery storage systems into high-rise multifamily buildings. The 2022 amendments, on a statewide basis, annually save approximately 33 million therms of fossil fuel natural gas and 1.3 billion kWh of electricity across the combination of both residential and commercial buildings relative to the 2019 Energy Code. This represents a reduction of 358,130 metric tons of CO2 equivalent emissions annually, and a total reduction of 71.46 million metric tons of CO2 equivalent emissions by 2050, per the Environmental Impact Report prepared as a part of the rulemaking.

The 2025 Energy Code was adopted in September 2024 with an effective date of January 1, 2026. The CEC updated the state’s two metrics to be based on the most recent forecast of demand over the coming 30 years and the most recent resource plans for energy system changes to address that demand. The CEC renamed the Time Dependent Valuation metric to be the Long-term System Cost metric. The 2025 code further updates baseline performance for single and multi-family buildings, including prescriptive compliance for single family buildings to use heat pumps for both space and water heating, and for multi-family buildings, to use heat pumps when individual water heaters are installed in dwelling units. The 2025 Energy Code also updated solar photovoltaic and battery storage systems to achieve cost effective installations in consideration of revised net billing and virtual net billing rules in California.

Last Reviewed: November 2024

The Connecticut Department of Administrative Service incorporated the 2021 IECC family of codes as part of the state building code-which was adopted in October 2022. As part of the 2022 state building code, the state will implement the 2021 IECC in residential buildings.  (Link).  

Details regarding the state's code adoption process and schedule can be found on its Code Adoption Webpage. In addition, Connecticut Law grants the State Building Inspector the authority to bypass the typical regulation adoption process, which can take several years (CGS 29-252b). In addition, the law mandates the state to adopt the national model code within 18 months of its publication. A few years ago, CT adopted two national model code cycles in one year.

The CT state building inspector is working with the Codes and Standards Committee to draft the 2025 state building code, which incorporates by reference the 2024 International Energy Conservation Code. The estimated date of adoption is Fall 2025. 

Last Reviewed: November 2024

The 2017 DC Construction Codes consist of the 2015 International Code Council (ICC) family of model codes, the 2014 National Electrical Code, and 2013 ASHRAE 90.1, as amended by the District of Columbia Municipal Regulations (DCMR) Title 12, Sections A through M.  The 2017 DC Construction Code took effect on May 29, 2020.  Applicability and provisions for the prior editions of the code, (for Permits issued, Applications Filed, Tenant Layouts and Permit Revisions) will be governed by the Transitory Provision stipulated in section 123. (Link)   

Both the commercial and residential building energy code was amended to strengthen energy efficiency in the District. Key elements of the new code require ENERGY STAR products for a variety of technologies and stringent gas efficiency. The high gas efficiencies required by this amended code remove the need for the energy efficiency utility to incentivize new construction gas projects, but moves the focus to strategic electrification for HVAC and water heating. 

The codes also include an alternative compliance pathway for net zero buildings, including LEED Zero Energy and LEED Zero Carbon, for both commercial and residential construction (link). The District also has a Green Construction Code that enhances energy efficiency requirements in addition to the energy code.  It applies to all commercial construction projects 10,000 square feet and larger and all residential projects that are 10,000 square feet and larger and four stories or higher.

Last Reviewed: November 2024

The 2020 Georgia State Minimum Standard Energy Code, based on the 2015 IECC with state specific amendments, went into effect January 1, 2020.

Last Reviewed: December 2022

The Idaho State Legislature adopted the 2018 IRC and IECC residential provisions with amendments during the 2020 legislative session, taking effect January 1, 2021. The amendments include: a blower door testing program for residential builders; energy rating index table for Idaho’s climate zones; and window u-factors and insulation tables based on Idaho’s climate zones. Approximately 96% of local jurisdictions are covered by building codes adopted by the state.

Local jurisdictions may not adopt more or less stringent code than the current building code approved by the state legislature. 

The 2022 legislative session heard two bills that focused on energy codes. HB 660 modifies the existing energy code to prohibit any city, county, incorporated or unincorporated area, special use district or any other local governmental entities of any kind from adopting energy code or related requirements that differ from or are more extensive than the requirements of the Idaho Energy Conservation Code. The Act became effective July 1, 2022. (Link)

Last Reviewed: November 2024

The Indiana Energy Conservation Code is state-developed and mandatory statewide. The latest code, referencing the 2018 IECC with amendments, was adopted in Indiana and became effective on December 26, 2019.

Last Reviewed: November 2024

Kansas is a home-rule state and thus has no statewide residential building code, though realtors and homebuilders are required to fill out an energy-efficiency disclosure form and provide it to potential buyers. Many jurisdictions have adopted the 2009 or 2012 IECC. Based on information obtained in a 2013 survey of local jurisdictions and 2011 U.S. Census permit data, it is estimated the almost 60% of residential construction in Kansas is covered by the 2009 and 2012 iterations of the IECC. 

Last Reviewed: November 2024

Residential buildings must meet the 2009 IRC with reference to the 2009 IECC. Multifamily residential construction three stories or less must comply with the 2012 IRC and the energy provisions of the 2009 IECC. Multifamily residential construction over three stories must comply with ASHRAE 90.1-2007.

Last Reviewed: November 2024

Effective March 25, 2019, the 2018 Maryland Building Performance Standards are mandatory statewide and reference the 2018 ICC Codes, including the 2018 IECC, for all new and renovated residential buildings. § 12-503 of the Public Safety article requires the Maryland Department of Labor to adopt the most recent version of the IECC within eighteen (18) months after it is issued and may adopt energy conservation requirements that are more stringent than the codes, but may not adopt energy conservation requirements that are less stringent. Modifications (e.g., innovative approach, design, equipment, or method of construction) are allowed if the modification can be demonstrated to offer performance that is at least the equivalent to the requirements of: 1.  the International Energy Conservation Code; 2. Chapter 13, “Energy Efficiency”, of the International Building Code; or 3. Chapter 11, “Energy Efficiency”, of the International Residential Code (see §12–503(b)(iii)) of the Public Safety Article).  Each locality in the state must adopt and begin enforcement of the code within 12 months of state adoption.

As of January 2022, the IECC 2021 is under review for adoption.

Adoption of energy codes is mandatory in Maryland.  After new editions of I-codes become available from the ICC, the Department of Labor is required to adopt the new codes within 18 months. After adoption, all local jurisdictions have up to 12 months to amend & adopt these new codes for local code enforcement. 

Last reviewed: November 2024

Michigan is operating under the 2015 Michigan Residential Code and the 2015 Michigan Uniform Energy Code. The state is currently in the process of completing an update of the residential energy code to the most recent IECC 2021 code. Public comments were received during a series of meetings and through written comments and ended on 2/22/2024. The final code is expected to go to JCAR for review/approval with the goal of the new code going into effect in the fall of 2024

Weakening amendments have been adopted for both the residential and commercial codes. Per analysis by the Midwest Energy Efficiency Alliance (MEEA), the Michigan-specific amendments to the residential code reduced the efficiency of the standard (2015 IECC) by 11%; the Michigan-specific amendments to the commercial code reduced the standard (ASHRAE 90.1-2013) by 1%.

Last Reviewed: November 2024

Mississippi's residential code is voluntary and is based on ASHRAE 90 – 1975 and the prior 92 MEC. Based on a June 2011 Energy Codes Economic Analysis conducted by BCAP and Southface, as well as additional data collected by MDA, approximately 60% (1.75 million out of a total 2.9 million residents) of the State’s population reside in cities or counties with building codes equivalent to 2003 IBC or higher, and the average code standard for these local jurisdictions is 2006 ICC. Jurisdictions can adopt more stringent codes, and several localities have done so for the residential code: Gulfport, Biloxi, Horn Lake, Ridgeland, Jackson, Greenville, Oliva Branch, Pascagoula, and Moss Point.

Last Reviewed: November 2024

Montana's residential building code, codified in ARM Title 24, Chapter 301.161, is mandatory statewide. Montana's residential code requires compliance with the 2018 IECC, with amendments. The residential code amended requirement for above grade walls to R-21 , does  not require continuous R-5 external insulation.  Blower door test amended to 4 ACH 50 , where 2018 IECC lists 3 ACH 50.  Building cavities allowed for return ducts if  ducts pass tightness test.  As listed in amendment - Exception: "Building framing cavities may be used for return ducts if there is no atmospherically vented furnace, boiler, or water heater located in the house outside of a sealed and insulated room that is isolated from inside the thermal envelope and if the duct system has been tested as having a maximum total leakage not greater than 4 cfm/SF. The room walls, floor, and ceilings shall be insulated in accordance with the basement wall requirements of Table R402.1.2."

Last Reviewed: November 2024

In July 2021, the 2021 IECC with Electric Vehicle ready appendices was adopted for residential buildings in Nevada. While the code is not being enforced statewide, local governments are not allowed to adopt less-efficient energy codes.

Last Reviewed: November 2024

On September 5, 2022, New Jersey adopted without amendments the 2021 International Energy Conservation Code (IECC) for residential structures.  New Jersey adopted the zero energy code provisions in the 2021 IECC-Appendix RC as optional at the discretion of the permit applicant.

For existing buildings, the Rehabilitation subcode (NJAC 5:23-6) applies certain energy conservation provisions of the new code based on the scope of the project.

Last reviewed: November 2024

On December 6, 2019, the Fire Prevention and Building Code Council voted to adopt major updates to the New York State Energy Conservation Construction Code, incorporating the 2018 International Energy Conservation Code (IECC) and ASHRAE 90.1-2016. Effective May 12, 2020, residential buildings must comply with the 2020 Energy Conservation Construction Code of New York State. 

Under New York State Energy Law, Article 11, local energy codes are permitted by law, as long as the local energy code is more stringent than the state energy code. The state developed a stretch energy code with contributions from an advisory group and technical working groups representing state and local government, utilities, design professionals, building trades and advocacy groups.   NYStretch Energy Code-2020 (NYStretch) was published July 2019 for voluntary, local adoption.  The Residential Provisions of NYStretch are approximately 19% more efficient than the 2020 New York State Energy Conservation Construction Code.  To date, NYStretch  has been adopted by 42 local governments, including New York City. The City of Ithaca includes NYStretch as an optional path in their Green Building Code. NYSERDA is promoting and supporting local adoption, and dozens of additional jurisdictions throughout the state and considering local laws to adopt NYStretch-2020.  NYStretch-2020 adoption is incentized until June 30, 2022 through NYSERDA's Clean Energy Communities Program (Link). The City of Ithaca includes NYStretch as an optional path in their Green Building Code. NYSERDA also worked with the State University of New York Construction Fund to pass a directive that all construction on its campuses will meet NYStretch provisions.

Last reviewed: November 2024

North Dakota is a home rule state and has no statewide mandatory energy codes. The state recently adopted an amended version of the 2021 IECC as its voluntary residential code. Approximately 91% of the state’s population lives in a jurisdiction that has adopted the ND State Building Code which includes the 2021 IECC.

Last Reviewed: November 2024

Oklahoma has in place mandatory statewide building codes for residential and commercial buildings. The Oklahoma Uniform Building Code Commission (OUBCC) reviews and recommends building codes for residential and commercial construction. Residential buildings must comply with the 2015 IRC; however, the energy chapter references the 2009 IRC. The 2018 International Residential Energy Code has been reviewed by an energy technical committee and will be sent to the Oklahoma Legislature to be considered for adoption as modified by the OUBCC energy technical committee.

While Oklahoma does not currently require all jurisdiction to adopt a statewide energy code, counties are allowed to participate in PACE programs for energy efficiency through the Oklahoma Energy Independence Act. In fact, on May 20th, 2020, Governor Kevin Stitt signed into law SB 1592 expanding the scope of the current Oklahoma Energy Independence Act to allow all properties but single-family residences to be eligible for the program. 

The jurisdictions listed here have adopted their own building codes. They represent approximately 40% of the population of Oklahoma, or 1,507,066 people (based on the 2010 Census).

Last Reviewed: November 2024

Pennsylvania adopted the 2018 IECC, which went into effect on February 14, 2022. 

Last reviewed: November 2024

On January 1, 2013, the 2013 South Carolina Energy Standard became effective. The residential provisions reference the 2009 IECC. Local jurisdictions may adopt more stringent energy codes.

Last Reviewed: November 2024

State building codes adoption and enforcement efforts fall under the purview of the State Fire Marshal’s Office within the Department of Commerce and Insurance (C&I). Any changes to building energy code must comply with the State’s rule-making procedures. On August 27, 2019, C&I conducted a rulemaking hearing to adopt the 2018 International Residential Code (IRC) and the 2018 International Energy Conservation Code (IECC) with amendments for residential one- and two-family dwellings and townhouses. The permanent rules were filed with the Secretary of State on April 21, 2020 and went into effect on July 16, 2020. See https://publications.tnsosfiles.com/rules_filings/04-25-20.pdf and https://www.energycodes.gov/adoption/states/tennessee for additional information. 

However, because Tennessee is a “home rule” State, significant variation exists in codes adoption and enforcement at the local level. Under Tennessee statute, all local jurisdictions must adopt a residential energy code that is within seven years of the most recently published energy code. All local jurisdictions may also opt out of residential building energy code adoption with a two-thirds majority vote of the local governing body. In addition, local jurisdictions cannot be required to adopt a local code that is more stringent than the one adopted by the State, but they may voluntarily choose to adopt an updated code version. If opting out, the vote must be completed after each local election cycle. As of June 2020, 93 jurisdictions have opted in to the state residential building code (apply the statewide building code to their jurisdiction and utilize the state’s building permit system and building inspectors), 82 jurisdictions have opted out (building codes are not recognized nor enforced), and 266 jurisdictions are exempt (building codes are adopted locally, meeting or exceeding the statewide standard; exempt jurisdictions hire their own inspectors and all paperwork is administered locally and audited on a 3 year cycle).

The State began implementation and enforcement of adopted energy codes for new building projects in July 2011. The State Fire Marshal’s Office requires a State building permit for new residential construction in areas of the State, except those where an exempt local government is enforcing a residential building code itself or where the local government has notified the Department it has opted out of the law. Building construction projects subject to code enforcement by the State Fire Marshal’s Office are required to obtain a State building code permit prior to commencing construction. The Department verifies contractors' licensure as part of the permitting process.

Given the recent update to the 2018 IRC and IECC residential energy codes, there are currently no jurisdictions that have adopted building energy codes that exceed the codes adopted by the State. It is expected that certain jurisdictions with near-term clean energy and carbon reduction goals will adopt the 2021 IRC and IECC for residential properties within the next few years.

A listing of the State’s currently adopted codes and codes history is available here: https://www.tn.gov/content/dam/tn/commerce/documents/fire_prevention/posts/2020-4-12_sfmo-code-adoption-and-history.pdf.

Last Reviewed: November 2024

Utah’s Uniform Building Code (UUBC) for residential building energy codes is mandatory statewide. Residential building construction must comply with an amended version of the 2015 IECC.

In 2019, HB 218 further amended the residential codes. Existing weakening amendments adopted in 2016 with automatic increment improvements effective January 2019 and 2021 include: 1.) A 5th compliance option, the Utah 2012 REScheck, which includes an equipment trade-off.  The required pass rate increased from 4% to 5%, January 1, 2021. 2.) Section R402 allows either blower door test or compliance to Table 402.4.1.1. The amended blower door requirement improved January 1, 2019 from 3.5 ACH to 3 ACH @50 pa for single family dwelling; however remains at 5 ACH @50 pa for townhouse/multi-family due to HB 218. 3.) Duct leakage testing is required with 20% of duct outside the thermal envelope. Allowed leakage dropped from 7 CFM/100 sq. ft. to 6 CFM/100 sq. ft. January 1, 2021. Amended ERI scores remain at 65 CZ-3, 69 CZ-5, and 68 CZ-6. HB 218 included one amendment strengthening the whole house fan efficacies to the 2018 IECC level.

While localities may adopt stretch codes, it is a difficult process to do so. Localities may only adopt stretch codes if approved through the state legislative process. Amendments may not be adopted at the local level. As a result, none have adopted stretch codes.

Last Reviewed: November 2024

With an effective date of January 18, 2024, Virginia's Uniform State Building Code (USBC) has been updated to incorporate energy efficiency provisions for commercial buildings of the 2021 IECC and ASHRAE 90.1-2019.  All buildings with permit application date of January 18, 2025 or after must comply.  Residential buildings must meet requirements of the residential provisions of the 2021 IECC, with two mild weakening amendments: (1) wall insulation R-Value maintained at R-15 or R-13+1; (2)  building thermal envelope air leakage rate not exceeding five air changes per hour. The code development process for the 2024 USBC (which includes the 2024 Virginia Energy Conservation Code), is anticipated to begin Q3 of 2024. The 2024 USBC will be using the 2024 I-Codes as the model codes.

Last reviewed: June 2024

West Virginia's residential building code is mandatory statewide; however, adoption by jurisdictions is voluntary. The 2022 West Virginia Legislature passed a bill updating the state’s building energy code to follow the 2015 IECC for residential buildings. The new residential code became effective August 1, 2022.

Last Reviewed: November 2024