State and Local Policy Database

Residential Codes

Mandatory residential building codes require a minimum level of energy efficiency for new residential buildings. The Department of Energy estimates that between 1992 and 2012, residential codes resulted in cumulative energy savings of 1.8 quads. They project that an additional 21.2 quads will be saved through 2040 due to residential building energy codes.

The Alabama Energy and Residential Code (AERC) Board adopted the 2015 Alabama Residential Energy Code. While the residential code is based on the 2015 IECC, state-specific amendments weaken it significantly, making it more efficient than the 2009 IECC but not equivalent to the 2015 IECC. The updated residential code took effect October 1, 2016. Local jurisdictions may adopt more stringent codes, and several have adopted the 2015 IECC without the state-adopted amendments. The AERC Board is preparing to begin consideration of the 2018 IECC and ASHRAE 90.1-2016.

Last Reviewed: August 2022

Alaska does not have a mandatory statewide code for new residential construction. However, since January 2019, residential construction projects financed by the Alaska Housing Finance Corporation are required to meet the state-developed Building Energy Efficiency Standards (BEES), which is based on the 2018 IECC with state-specific amendments. Since the corporation finances approximately 20% of the market share, the majority of homes in Alaska are built to this standard. In addition, research has found that about 68% of new residential construction adheres to BEES.

Last reviewed: May 2022

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 Updated: September 2019

The Arkansas Energy Code for New Building Construction is mandatory state-wide for both residential and commercial buildings. The residential energy code is based on the 2009 IECC with amendments. This code became effective on January 1, 2015.

The 2014 Arkansas Energy Code is a weakened version of the residential 2009 IECC.  Specific weakening amendments include Fenestration U-factor, Slab Insulation, Duct Leakage Testing, Lighting Efficacy, and Programmable Thermostats.  Specific strengthening amendments include Fenestration Solar Heat Gain Coefficient. You will find a download of the residential amendments, titled "2014 Arkansas Energy Code" at the following link.

Local jurisdictions that issue building permits are required to adopt the state energy code.  Enforcement is handled exclusively by the local jurisdiction. In a study completed July 2018, 91 municipalities had acknowledged the state energy code through a local ordinance.  As of December 2020, a relatively few jurisdictions (Fayetteville, Little Rock, North Little Rock, and possibly more) have passed ordinances that enforce a stronger code than the 2014 Arkansas Energy Code. 

Last Reviewed: May 2021


The 2019 California Energy Code for low-rise residential buildings took effect on Jan. 1, 2020, and is the first in the nation to require photovoltaic (PV) systems. The standards were officially published by the International Code Council (ICC) as the California Energy Code (CEC) on July 1, 2019. Energy Code residential performance requirements are expressed in terms of Energy Design Ratings (EDRs), with an index scoring system aligned with RESNET’s 100-point scale, using a 2006 International Energy Conservation Code (IECC) reference building. The Energy Code establishes two separate EDRs, one for energy only and the other for photovoltaic systems and other demand response (DR) measures (such as battery storage and DR-controlled Heat pump Water Heaters). In June 2017 the California Energy Commission certified to U.S. DOE that the 2016 Energy Code exceeded IECC 2015 by 29% on average for the residential building types analyzed).  Compared to the 2016 Energy Code, the 2019 Energy Code saves an additional 79% of electricity, 17% of demand, and 9% of natural gas for single-family buildings, and 53% on an energy cost basis. The 2019 Energy Code reduces the energy consumption of homes built compared to the 2015 IECC by roughly 80%, using California’s Time Dependent Valuation metric. They cut the carbon footprint of homes built to California’s prior 2016 Energy Code in half.

In 2021, the CEC adopted the 2022 Energy Code with an effective date of January 1, 2023. The amendments in this triennial update that apply to residential buildings include amendments that shift the baseline for minimum building performance as well as for prescriptive compliance to the use of heat pumps for space and/or water heating, as well as establish 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, would 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.

Last Reviewed: September 2022

Colorado is a home-rule state, but under state statute, local jurisdictions are required to adopt one of the three most recent versions of the International Energy Conservation Code at a minimum, upon updating any other building code. In 2022, a new law was passed (HB22-1362) to update the minimum building energy codes that a jurisdiction with building codes needs to adopt, upon adopting or updating any other building codes. The 2015 IECC is the adopted code for all modular homes. Local governments are permitted to develop or adopt any stretch, or advanced building code they see fit. Some have adopted EV-ready codes.

As of May 2022, nearly 87% of Colorado's population is on the 2015, 2018, or 2021 IECC. Seventy-five jurisdictions, covering nearly 60% of the state's population, have adopted the 2018 or the 2021 IECC so far, with many more in the process or under consideration. 

As a home-rule state, local governments are permitted to develop or adopt any stretch, or advanced building code they see fit. Some have adopted EV-ready codes.

  • The City of Boulder adopted its own Energy Conservation Code for residential and commercial buildings.
  • Pitkin County has an Efficient Building Ordinance. 
  • City and County of Denver (link). Denver has also developed a Net Zero Energy roadmap and has begun stakeholder meetings to update its building codes by the end of 2021.
  • Fort Collins (link)

Last Reviewed: May 2022

The Connecticut Department of Administrative Service adopted the 2015 IECC for residential and commercial construction effective October 1, 2018.  However, the CT Codes and Standards Committee is reviewing the 2021 IECC with the goal of adopting the new state building code in October 2022 (Link).  

Details regarding the state's code adoption process and schedule can be found on its Code Adoption Webpage. In addition, Connecticut Law now provides the State Building Inspector and Code Committee a process to adopt and implement the latest IECC during the same year.  

Last reviewed: August 2021

Delaware adopted 2018 IECC effective June 11, 2020.  Secretary’s Order No: 2020-CCE-0014 was signed on April 28, 2020, approving the proposed amendments to 7 DE Admin. Code 2101: Regulations for State Energy Conservation Code. The final regulation and Secretary's Order was published in the June 1st Monthly Register of Regulations and with an effective date of June 11, 2020. The regulations adopt the 2018 IECC in its entirety by reference.  The energy codes come in to force 6 months after the effective date (December 11, 2020). Residential and commercial codes are reviewed triennially by the Delaware Energy Office within the Department of Natural Resources and Environmental Control.

Review of the 2021 IECC has begun with adoption anticipated in June 2023.  Activities and events associated with the next code adoption cycle are posted on the DNREC webpage.

The only amendment to the model codes (2018 IECC and ASHRAE 90.1-2016) is a slight strengthening amendment.  The regulations adopted by DNREC require testing for duct and building envelope tightness (as required by the model codes) to be conducted by a certified DET verifier.  “DET verifier” means a certified Duct and Envelope Tightness verifier. A certified DET verifier shall be a certified Home Energy Rating Systems (HERS) rater, or be a certified Home Performance with ENERGY STAR contractor, or be a Building Performance Institute (BPI) Heating Professional to perform duct tightness testing or a BPI Building Analyst or Envelope Professional to perform building tightness testing, or successfully complete a course that is approved by the Department of Natural Resources and Environmental Control.  See regulations at:

Additionally, the City of Newark has adopted a stretch code.  Middletown is considering adoption.  New Castle County Council is working on development of a Zero Net Energy Buildings stretch code amendment that would be applied to all municipalities in the county.  

Last reviewed: June 2022 

The District has passed new energy codes recently. Washington DC's energy codes are mandatory across the District. 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: June 2022

The Florida Building Code is the statewide building code for all construction in the state. Every local government must enforce the Building Code and issue building permits.  The Florida Building Code 7th Edition took effect Dec. 31, 2020, replacing the Florida Building Code 6th Edition. While the Florida Building Code 6th Edition was based off of the 2015 International Building Code, the Florida Building Code 7th Edition is based off of the 2018 International Building Code. Compliance with the code is mandatory for all new construction including residential buildings.

Last Reviewed: June 2022

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: July 2021

On December 15, 2020, the Hawaii State Building Code Council adopted the 2018 IECC with state-specific amendments. The code took effect for State Government buildings on December 14, 2021 unless the Governor specified an earlier date.  The counties have until December 14, 2022 to adopt the code with their amendments. (Link)

The County of Hawaii adopted the code in 2021. For the link to the Hawaii Amendments to the 2018 IECC, please see the Hawaii State Building Code Council's website.

The counties are permitted to adopt more stringent energy codes.  The county of Honolulu included requirements for EV-ready and PV-ready provisions in its 2015 IECC, and is planning to do so in its 2018 IECC.

Last Reviewed: July 2022

The Idaho State Legislature adopted the 2018 IRC and IECC residential provisions with amendments during the 2020 legislative session; these codes will take effect on January 1, 2021. The 2018 IECC standard was adopted in January 2021. This code adoption will replace Idaho’s current building code standards and bring all jurisdictions with building codes up to the 2018 IECC standard. 

The 2018 IECC standard is the current suite of codes and was amended to meet Idaho needs in 2021. The changes included: 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: July 2022

By law Illinois is required to adopt the latest IECC, although the Capital Development Board may recommend amendments. Current code, effective July 2019, requires residential construction to meet 2018 IECC standards with state-specific amendments. 

Last reviewed: July 2019

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: July 2022

The Iowa State Energy code is mandatory statewide for residential buildings, although jurisdictions are free to adopt stricter codes. Residential buildings must comply with the 2012 IECC, with state-specific amendments.

Last Reviewed: July 2022

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: September 2019

As of October 1, 2014, the 2013 Kentucky Residential Code (KRC) mandates residential buildings must comply with the 2009 IECC or IRC with state amendments.

Last Reviewed: September 2019

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: September 2019

In 2019, the Maine Legislature enacted three important amendments to residential building codes. First, Public Law (PL) 391 established that the Maine Uniform Building and Energy Code (MUBEC) must update the code from the 2009 IECC to the 2015 or a newer version, that it must be kept up to date with the latest version of the IECC, and required that it be applied in every municipality in Maine, regardless of population. (Pursuant to existing law, enforcement of the code is voluntary in municipalities having fewer than 4,000 customers, representing about 40% of the population). Second, PL 517 modified and improved the oversight and training of code enforcement officers. Third, PL 392 required the MUBEC to establish a stretch code that may be adopted by any municipality.

In 2019, the Technical Codes and Standards Board formally decided to adopt the 2015 IRC, IEBC, and IECC and commenced a rulemaking process to update the Maine code. In 2020, the Technical Codes and Standards Board completed its rulemaking to implement the 2015 International Energy Conservation Code, which takes effect on July 1, 2021 and also adopted the 2021 IECC to serve as an appendix to the IECC as a statewide “stretch code” that municipalities may elect to adopt.

Last Reviewed: May 2021

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.

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: July 2021

The Board of Building Regulations and Standards (BBRS) has adopted the IECC 2018 with MA amendments as part of the 9th edition of the MA state building code. The updated code became available on Feb 8, 2020,  with the 2015 code expiring on Aug 8, 2020. Due to Covid-19 the BBRS in considering extending the end date for the 2015 code to Jan 1, 2021. The new energy chapters reference the IECC 2018 with strengthening amendments. Strengthening amendments include a new section R407, solar readiness requirements and HERS 55 rather than 62. The Board did not make significant changes to the residential stretch energy code, which continues to require HERS 55 or less for new construction with incentives for solar PV and onsite renewable energy or cold-climate heat pumps. Alternative residential stretch code options include meeting the Energy Star Homes 3.1 standard or the Passive House Standard.

Residential strengthening amendments include a lower HERS rating of 55 (IECC2018 is at 62), the removal of section R405 which is often the least stringent code option, and a new prescriptive section R407. The residential stretch energy code continues to require HERS 55 or less for new construction with incentives for onsite renewable energy and/or cold-climate heat pumps. Alternative residential stretch code options include meeting the Energy Star Homes 3.1 standard or Passive House Certification.

Massachusetts has a statewide stretch energy code that has now been adopted by 289 of the 351 cities and towns  (link). The Stretch energy code requires performance standards to be met above and beyond the baseline code. The options for residential units are 3rd party verified HERS rating, Energy Star 3.1 certification or Passivehouse certification. For commercial buildings over 100,000 sq ft or for some load-intensive buildings over 40,000 sq ft it requires demonstrating 10% or greater energy reduction relative to ASHRAE 90.1-2013 Appendix G after incorporating the MA strengthening amendments (ie. C406).

The state's Next Generation Roadmap for Climate Policy legislation signed in March 2021 also calls for development of an opt-in net-zero stretch code that defines a net-zero building and net-zero building performance standards.

Last reviewed: July 2021

The 2015 Michigan Residential Code went into effect in February 2016 and is based on the 2015 IECC with Michigan-specific weakening amendments. 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 3/16/2022. There will be another draft released after consideration of the comments submitted and then there will be another public comment period for consideration before the final version is published. The Bureau of Construction Codes is planning to have this code finalized before the end of the calendar year.

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: June 2022

Minnesota's residential building code is mandatory statewide. The IECC 2012 was adopted in August 2014 and went into effect February 2015.

Last Updated: July 2021

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: September 2020

Missouri is a home-rule state and thus has no mandatory state-wide codes. State-owned residential buildings must comply with latest edition of the MEC or the ASHRAE 90.2-1993 (single-family and multifamily buildings). Missouri maintains a database of building code adoptions in local jurisdictions. Approximately 50% of the state’s population is covered by the 2009, 2012, 2015, or 2018 IECC or equivalent codes.

The building codes adopted by jurisdictions throughout the state are listed on the State of Missouri Data Portal.

Last Reviewed: May 2022

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: July 2022

Nebraska is a home-rule state, but its residential energy code, referred to as the Nebraska Energy Code (NEC), is mandatory statewide.

Residential buildings are required to comply with the 2018 NEC/IECC beginning July 1, 2020, with administrative amendments. Local jurisdictions that adopt thermal and /or energy codes may make modificiations to the NEC following review by the Nebraska Department of Environment and Energy. In 2017, the Energy Assistance Division of the Nebraska Energy Office, now the Dept. of Environment and Energy, conducted an energy impact study on the adoption of the 2018 IECC. 

Effective July 1, 2020, the Nebraska Energy Code will be based on the 2018 IECC with administrative amendments. 

Last Updated: September 2020

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: May 2022

Effective September 2019, the NH legislature adopted the 2015 ICC codes with state-specific energy related amendments to the 2015 IRC. The IRC amendments will expire 30 months after adoption, in March 2022, at which time the full suite of energy-related IRC codes will go into effect. The code is mandatory statewide. The NH Building Code Review Board is currently reviewing the 2018 ICC chapters and may propose them, with amendments, for adoption in 2022.

Last Reviewed: June 2021

Compliance with the energy provisions of the New Jersey Uniform Construction Code (UCC) for residential is mandatory statewide as of September 21, 2015, with a six-month grace period for the previously adopted codes to be used to not disrupt projects currently in design-stage. Residential construction must comply as mentioned above. The code includes a modification to Section N1102.4.1/R402.4.1 (Building thermal envelope) of the IRC and IECC which allows for either a visual inspection with checklist or [blower door] testing for compliance with the air barrier and insulation aspects of the building thermal envelope requirements. If testing is used, the 2015 criteria of 3 air changes per hour is the criteria to meet. 

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

Last reviewed: August 2021

In August 2020, the New Mexico Construction Industries Commission (CIC) voted to adopt the 2018 New Mexico Energy Conservation Code (NMECC), based on the 2018 IECC with state-specific amendments. The code applies statewide. Local building jurisdictions must meet or exceed the state code which becomes the minimum code. Amendments are minor and deal mostly with providing flexibility to builders. 

Because localities are permitted to adopt stretch codes, the City of Santa Fe and Town of Taos have adopted more stringent building codes. The City of Albuquerque is also planning to adopt a stretch code beyond the 2018 IECC. Builders can also use the updated NM Energy Conservation Code Residential Applications Manual to comply when building a passive solar or high mass home.

Last Reviewed: June 2022

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: July 2022

The 2018 North Carolina Energy Conservation Code (NCECC) is mandatory statewide for residential buildings. The residential code is based on the 2015 IECC with amendments. State Building Code Council develops new codes on a six-year cycle. Most recent update was effective January 1, 2019.  (Source)

Last reviewed: July 2021

North Dakota is a home rule state and has no statewide mandatory energy codes. The state recently adopted an amended version of the 2018 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 2018 IECC. The state is currently going through the adoption of the 2021 ICC codes including the 2021 IECC. The codes will become effective on January 1, 2023.

Last Reviewed: June 2022

Effective July 1, 2019, a new residential code will be in effect based upon the 2018 IRC/IECC with amendments. Previously residential home builders were required to comply with the 2009 IECC. 

Amendments were made to both the commercial and residential model code energy requirements.  Weakening amendments to the  residential energy provisions relate to basement and crawl space wall R-values, air leakage rates and the allowance to utilize framing cavities as return ducts.

Local jurisdictions are not permitted to adopt energy codes that conflict with the energy codes adopted by the state. The adopted commercial and residential energy codes are applicable to 100% of the construction activity that takes place in the state.  However, local jurisdictions have the option of enforcing residential code provisions, including energy conservation requirements.

Last reviewed: July 2022

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 in 2023 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 Indepence Act. In fact, on May 20th, 2020, Governor Kevin Stitt signed into law SB 1592 expanding the scope of the current Oklahoma Energy Indepence 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: May 2022

Oregon’s Building Code Division (BCD) produces Chapter 11 of the Oregon Residential Specialty Code (ORSC) which is mandatory statewide. The 2021 ORSC has been effective since April 1st, 2021, with a 6-month phase-in period. The ORSC is a homegrown code fully compatible with the IECC, which includes a mandatory additional efficiency package pathway for envelope efficiency and equipment. Significant changes found in the 2021 ORSC include locating HVAC ducts inside the thermal envelope or deeply burying them, a 10% reduction in window U-value, prescriptive air sealing requirements, and mandatory balanced whole-house ventilation. High-efficiency lighting is also required with exceptions for up to (2) two interior and (2) exterior fixtures. Those fixtures must be on automated control which equates to approximately 98% of lighting fixtures being high efficiency.

US Department of Energy (BECP Program) has certified the 2021 ORSC to be better than the 2018 IECC.

Part of the residential code update process is a target in an Executive Order from 2017 (EO 17-20) that includes equivalent performance to the Department of Energy (DOE) Zero Energy Ready Home (ZERH) by October 1, 2023. An Executive Order issued last year (EO 20-04) builds on EO 17-20 and provide an aggressive target for both Residential and Commercial codes to be 60% better than the baseline year of 2006, by the year 2030. Oregon is on track to meet these goals. The Oregon Building Codes division has announced that work will begin on the 2023 ORSC. BCD will work with the Residential and Manufactured Structures Board (RMSB) and statewide stakeholders starting in July 2022.

Last reviewed: July 2022

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

Last reviewed: June 2022

On June 10, 2021, Rhode Island formally adopted the 2018 IECC for residential buildings, with state-specific amendments. The code went into effect on February 1, 2022 and is mandatory statewide. While Rhode Island is a home rule state, towns are not permitted to adopt a code that is different from the state's. The code contains several amendments that diverge from the ICC published version of the 2018 IECC. The residential code utilizes the 2009 IECC insulation tables, which is not as rigorous as the 2018 IECC.  Rhode Island also requires performance testing, but the required air exchange rate is not as rigorous as the 2018 IECC. As part of Rhode Island’s Energy Efficiency Procurement Plan, a Building Codes & Standards Initiative was approved by the Rhode Island Public Utilities Commission, and a stated feature is the continued support and maintenance of a “stretch” code targeting “15% more energy efficiency than buildings constructed according to the prevailing path.” This effort was pursued in conjunction with the Rhode Island Building Code Commission and the RI Builder’s Association.

Issued in December, 2015, Executive Order 15-17 directs the Office of Energy Resources to coordinate with the Energy Efficiency and Resource Management Council, National Grid, and the Green Building Advisory Committee to establish a voluntary aspirational or stretch building code based on the International Green Construction Code or equivalent standards. Rhode Island currently has a voluntary stretch code for both commerical and residential buildings that went into effect February 2018. 

In 2022, the Rhode Island Building Code Commission is working on adopting the next iteration of the State's building code which will be based on the 2021 International Code and the voluntary stretch code will be updated to stay ahead of the state's base code.

Last reviewed: June 2022

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: September 2019

South Dakota has no mandatory statewide energy codes for residential construction. Codes are adopted by jurisdiction voluntarily. As of July 2011, state law established the 2009 IECC as a voluntary residential standard, however most jurisdictions have adopted codes based on the 2015 IECC. Local jurisdictions also have authority to adopt various residential building and energy codes, including IRC and IECC.

Last Reviewed: June 2022

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 weakening amendments for residential one and two family dwellings and townhouses. The rule adopts the 2015 IRC seismic design categories (seismic map) instead of the 2018 seismic design categories (seismic map), and retains the 2009 IRC and IECC requirements for Testing, Duct Testing and Air Leakage, Insulation and Fenestration Requirements. The rule removes the requirement that the permit be purchased in the jurisdiction where the work will be performed, and the rule also allows a local government to request a building standard less stringent than the state standard adopted by a different jurisdiction. The permanent rules were filed with the Secretary of State on April 21, 2020 and are expected to go into effect on July 16, 2020. See the Rulemaking Hearing Rule(s) Filing Form (the amendments can be found on page 2 and 3) and the EERE Building Energy Codes Program page 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 May 2019, 92 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), 80 jurisdictions have opted out (building codes are not recognized nor enforced), and 264 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). More recently, C&I reports that as of June 2020, 165 local jurisdictions have adopted building energy codes that exceed the 2009 IECC adopted by the State. Of those, 34 local jurisdictions have already adopted the 2018 Residential IECC, and 21 have adopted the 2015 IECC.

Moreover, a large majority of Tennessee's construction activity occurs in the greater areas of Memphis, Knoxville, Chattanooga, and Nashville, all of which have building codes which meet or exceed the State's minimum building code. As of May 2019, roughly 770,000 Tennessee residents live in jurisdictions with “opt-out” status. Subtracting this number from Tennessee’s total population (6,829,000), an estimated 6,059,000 residents—89% of the state’s population—live in jurisdictions with building code adoption.

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.

Last Reviewed: September 2020

Texas' building codes are mandatory for residential construction. The Texas Building Energy Performance Standards requires single family homes to comply with the 2015 IRC and all other residential buildings to comply with the 2015 IECC. For all buildings, jurisdictions can choose to adopt more stringent standards. More than 50 jurisdictions, representing approximately 5.3 million people, have adopted codes more stringent than the minimum state requirements. 

Last Reviewed: September 2020


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: June 2022

The Vermont Residential Building Energy Standards (RBES) are mandatory statewide. The current RBES became effective September 1, 2020 and is based on the 2015 Vermont RBES language and also includes all the IECC 2018 energy efficiency requirements as well as select language updates and additional, more stringent Vermont energy efficiency requirements.  The 2020 RBES include the following: improved insulation levels; improved window U-values; blower door testing required; EV charging infrastructure required for multifamily buildings of 10 or more units, and encouraged for all buildings; Solar ready design encouraged; more high efficiency lighting; and more efficient ventilation fans. The state is required by statute to update its energy codes every three years.

Act 89 of 2013 gives the Vermont Public Service Department the authority to develop stretch codes and municipalities have the option of adopting them. The state's Residential Stretch Energy Code went into effect December 1, 2015 and was updated in 2019 with a September 1, 2020 effective date.  The 2020 RBES Stretch code includes solar ready requirements and EV charging infrastructure required for single family housing and multifamily buildings of 10 or more units.  Any residential projects encompassed by Act 250 are required to comply with the Residential Stretch Code.  Both Residential Base and Stretch Energy Codes also allow renewable energy to be used to meet the target Home Energy Rating Scores for compliance. The Vermont PSD is currently in the process of updating the RBES and expect to have the new standards adopted by December, 2022 and in effect by September, 2023.

Last reviewed: June 2022 

With an effective date of July 1, 2021, Virginia's Uniform State Building Code (USBC) has been updated to incorporate energy efficiency provisions for commercial buildings of the 2018 IECC and ASHRAE 90.1-2016.  All buildings with permit application date of July 1, 2022 or after must comply.  Residential buildings must meet requirements of the residential provisions of the 2018 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 2021 USBC (which includes the 2021 Virginia Energy Conservation Code), is currently underway. The 2021 USBC will be using the 2021 I-Codes as the model codes.

Last reviewed: June 2022

The 2018 Washington State Energy Code is a state-developed code that is mandatory statewide. Based originally on the 2018 IECC it has been extensively amended to reach state specific energy reduction targets. The 2018 Washington State Energy Code provides greater savings than the 2018 IECC.
In December of 2019 the state building code council adopted the 2018 Washington State Energy Code, which became effective February 1, 2021. The evaluation of code outcomes notes that the state is on track to achieving state specific energy reduction mandates, having incorporated code changes achieving 40% reduction in whole building energy use compared to the 2006 edition of the WA Code. The state energy office has completed a preliminary comparison of the result of the Washington Study to the Energy Savings Analysis: 2018 IECC for Residential Buildings completed by DOE.  While it is difficult to make direct comparisons between these studies, it's estimated that the state code provides greater savings than the 2018 IECC by at least 5% when weighting factors for climate zone, building size and fuel mix are accounted for. The new code will be implemented Nov. 2020. 

The 2018 Washington State Energy Code specifically implements a standard that directly addresses carbon emissions reductions. This provide good incentives that encourage homes using high efficiency heat pumps and water heating.

Washington State is noted as the only state with energy code improvement requirements in statute. RCW 19.27a.160 (2009) “The council shall adopt state energy codes from 2013 through 2031 that incrementally move towards achieving the seventy percent reduction in annual net energy consumption”.

Executive Order 20-01 requires state government agencies in Washington to design and construct state-owned buildings to zero-energy or zero-energy capable standards, and include consideration of embodied carbon. The State Efficiency and Environmental Performance (SEEP) Office at Commerce supports construction of zero-energy buildings and has developed a Zero Energy Toolkit to help guide state projects.  

Last reviewed: June 2022

West Virginia's residential building code is mandatory statewide; however, adoption by jurisdictions is voluntary. The 2013 West Virginia Legislature passed a bill updating the state’s building energy code to follow the 2009 IECC for residential buildings. The new residential code became effective November 30, 2013.

Last Reviewed: September 2020

The state-developed residential code, referred to as Wisconsin Administrative Chapter SPS 322, Wisconsin Uniform Dwelling Code (UDC), is mandatory statewide for one- and two-family dwellings and incorporates the 2009 IECC with state amendments. These amendments are more restrictive for underfloor insulation for heated slabs. Local governments cannot modify the UDC and are required to enforce the UDC. 

Last Reviewed: September 2019


Wyoming's residential building code is voluntary. Known as the ICBO Uniform Building Code, it is based on the 1989 MEC and may be adopted and enforced by local jurisdictions. Some jurisdictions have adopted more stringent codes than the voluntary standard: the 8 most populated cities and counties in Wyoming have an energy code that meets or exceeds the IECC 2006 or equivalent. Teton County and Jackson are moving to the IECC 2012; Cheyenne adopted the IECC 2009; Casper, Rock Springs, and Gillette adopted a modified IECC 2006.

Last Reviewed: September 2019