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 recently 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 2020

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: September 2020

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.  

Last Reviewed: September 2019

 

The 2016 Building Energy Efficiency Standards were adopted in June 2015, effective January 1, 2017 In June 2017 the California Energy Commission certified to U.S. DOE that the 2016 Standards exceed IECC 2015 by 29% on average for the residential building types analyzed (see Energy Commission Residential Energy Efficiency Comparison).  The 2016 Reach Standards, published in the California Green Building Standards (CALGreen), were adopted in October 2015, effective January 1, 2017, and establish standards for Energy Design Ratings that are 15% (Tier I) and 30% (Tier II) beyond the mandatory standards, as well as a Zero Net Energy Design designation, which local governments consider for adoption as local ordinances.

In May 2018, the CEC adopted the 2019 Building Energy Efficiency Standards, which take effect on Jan. 1, 2020, and are the first in the nation to require solar. The codes focus on four key areas: smart residential photovoltaic systems, updated thermal envelope standards, residential and nonresidential ventilation requirements, and nonresidential lighting requirements. Compared to the 2016 Standards, the 2019 Standards save 79% of electricity, 17% of demand, and 9% of natural gas for single-family buildings, and 53% on an energy cost basis.

Last Updated: July 2019

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. The 2015 IECC is the adopted code for all modular homes.

As of May 2020, 75% of Colorado's population is on the 2012, 2015 or 2018 IECC.

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)
  • Fort Collins (link)

Last Reviewed: May 2020

Following a review that began in January 2017 by the state's Codes and Standards Committee and Department of Administrative Services, state regulators voted in July 2018 to move forward with adoption of the 2018 Connecticut State Building and Fire Safety Codes, which include the 2015 IECC for residential and commercial construction. The Connecticut Department of Administrative Service adopted the 2015 IECC effective October 1, 2018.

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 Updated: July 2019

Residential construction in Delaware must comply with a weakened version of the 2012 IECC. The state began reviewing the 2015 and 2018 IECC in 2018. Residential and commercial codes are reviewed triennially by the Delaware Energy Office within the Department of Natural Resources and Environmental Control.

Last Updated: September 2019

Washington DC's energy codes are mandatory across the District. For residential buildings, builders must comply with the 2013 DC Energy Conservation code, which is roughly equivalent to the 2012 IECC.  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: September 2019

Effective December 31, 2017, Florida law requires that residential buildings comply with the 6th Edition (2017) Florida Building Code, Energy Conservation. The 6th Edition (2017) Florida Building Code, Energy Conservation consists of the foundation code 2015 IECC and amendments. (See https://codes.iccsafe.org/public/collections/FL). The Florida Building Commission certified in letters to the U.S. Department of Energy that the new code meets or exceeds 2015 IECC standards. Compliance with the code is mandatory for all new construction including alteration to existing buildings.

Last Reviewed: September 2019

 

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: August 2020

In July 2015, the Hawaii State Building Code Council adopted the 2015 IECC with state-specific amendments. The new codes took effect on July 1, 2015. However, until each county adopts the 2015 IECC, the counties of Hawaii, Maui, and Honolulu enforce the 2006 IECC; Kauai, the 2009 IECC. 

Last Reviewed: September 2019

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. 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 suite of codes was amended to meet Idaho needs. 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 Iocal jurisdictions are covered by building codes adopted by the state. 

Last Reviewed: September 2020

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: August 2020

The Iowa State Energy code is mandatory statewide for residential buildings, although jurisdictions are free to adopt stricter codes. As of March 2014, residential buildings must comply with the 2012 IECC, with state-specific amendments. 

Last Reviewed: September 2019

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.

Last Reviewed: June 2020

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 Maryland Code requires the Department of Housing and Community Development 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. Each locality in the state must adopt and begin enforcement of the code within 12 months of state adoption.

Last Updated: July 2019

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.

Last reviewed: August 2020 

The 2015 Michigan Residential Code went into effect in February 2016 and is based on the 2015 IECC with Michigan-specific weakening amendments.

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: May 2020

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

Last Updated: August 2020

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, or 2015 IECC or equivalent codes.

Last Reviewed: September 2019

Montana's residential building code, codified in ARM Title 24, Chapter 301.160, is mandatory statewide. Montana's residential code requires compliance with the 2012 IECC, with amendments. The residential code was amended to not require continuous R-5 external insulation. 

Last Reviewed: August 2020

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 adminiatrative amendments. 

Last Updated: September 2020

On July 1, 2018, the 2018 IECC became mandatory for residential buildings. While the code is not being enforced statewide, a significant number of local governments are in the process of adopting it. Local governments are not allowed to adopt less-efficient energy codes.

Last updated: September 2019

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, at which time the full suite of energy relate 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 2021.

Although New Hampshire is not a home rule state, statutes allow municipalities to adopt amendments and codes provided they exceed the State Building Code. The town of Durham has adopted the 2018 IECC energy code.

Last Reviewed: May 2020

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: July 2019

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. An additional requirement,  thermal bypass check list has been added to ensure that contractors meet the indoor air change requirement before they finish a home. There are exceptions for very rural parts of New Mexico.  For example, the Blower Door test will be required for major population counties. Check lists will be allowed for very rural areas. Compliance paths are also available for passive solar and high mass buildings which are common in New Mexico.

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 strech 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: August 2020

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 New York City, the City of Beacon and Hastings-on-Hudson. The City of Ithaca includes NYStretch as an optional path in their Green Building Code. NYSERDA is promoting and supporting local adoption in dozens of additional jurisdictions throughout the state and 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: June 2020

Effective January 1, 2019, 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. 

Last Updated: September 2019

 

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.

Last Reviewed: September 2020

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: August 2020

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.

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 at the following link have adopted their own building codes.  https://documentcloud.adobe.com/link/track?uri=urn:aaid:scds:US:cd7524a8-a963-4762-ad20-e0f959419d8b

They represent approximately 40% of the population of Oklahoma, or 1,507,066 people (based on the 2010 Census).

Last Reviewed: September 2020

The 2014 Oregon Energy Efficiency Specialty Code is mandatory statewide. Its provisions are developed by the state and are not based on a model code. The state currently enforces the 2014 Oregon Residential Specialty Code (ORSC), which has been certified to US DOE as equivalent/more efficient to IECC 2015. Oregon has approved IECC 2015 as an alternative and is putting in place provisions for it to replace the current Reach Code. Reach Code compliance is mandatory for all new state-owned and occupied buildings and substantial remodels. Oregon adopted a new Residential Code in 2017 (2017 Oregon Residential Specialty Code, or 2017 ORSC), which became effective October 1, 2017, with a 90-day phase-in period. The 2017 ORSC is based on the 2015 IECC with Oregon amendments, which include mandatory alternative efficiency package pathways for envelope efficiency and equipment such as furnaces, water heaters, and heat pumps that exceed federal minimums.

Last Updated: July 2019

In May 2018 Pennsylvania adopted of the 2015 IECC (some with amendments) effective October 1, 2018.

Last reviewed: July 2019

On July 1, 2013, Rhode Island formally adopted the 2012 IECC for residential buildings, with state-specific amendments. The code went into effect on October 1, 2013 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 2012 IECC. The residential code utilizes the 2009 IECC insulation tables, which is not as rigorous as the 2012 IECC.  Rhode Island requires performance testing but does not require that the air exchange rate meet code. While there is no current stretch code, as part of the Rhode Island’s Energy Efficiency Procurement Plan, a Building Codes & Standards Initiative has been approved by the RI Public Utilities Commission, and a stated feature is the development of a “stretch” code targeting “15% more energy than buildings constructed according to the prevailing path.” This effort is being pursued in conjunction with the RI 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 by 2017. Rhode Island now has a voluntary stretch code for residential buildings.

Last Updated: July 2019

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: September 2019

 

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 are expected to go 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.

Weakening Amendments: The 2018 IRC was adopted with weakening amendments. 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 amendments can be found on page 2 and 3 of the Rulemaking Hearing Rule(s) Filing Form: https://publications.tnsosfiles.com/rules_filings/04-25-20.pdf.

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).

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.

As of June 2020, C&I reports that 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.

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 2019

 

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 include: 1.) A 5th compliance option, the Utah 2012 REScheck, which includes an equipment trade-off.  The required pass rate increased from 3% to 4%, January 1, 2019. 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 5 ACH to 3.5 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 25% of duct outside the thermal envelope. Allowed leakage dropped from 8 CFM/100 sq. ft. to 7 CFM/100 sq. ft. January 1, 2019. 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: September 2019

The Vermont Residential Building Energy Standards (RBES) are mandatory statewide. The current RBES became effective March 1, 2015 and is based on the 2015 IECC with Vermont-specific amendments. The 2020 RBES will become 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 r;equired by statute to update its 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 projects encompassed by Residential Act 250 are required to adopt 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.

Last reviewed: August 2020

With an effective date of September 4, 2018, Virginia's Uniform State Building Code (USBC) has been updated to incorporate energy efficiency provisions for commercial buildings of the 2015 IECC and ASHRAE 90.1-2013.  All buildings with permit application date of September 4, 2019 or after must comply.  Residential buildings must meet requirements of the residential provisions of the 2015 IECC, with weakening amendments removing required envelope pressure (blower door) testing and improvements to attic/wall insulation R-values

Residential buildings had previously been required to comply with the 2012 IRC; however, a few technical amendments had rendered the code equivalent to the 2009 IECC.

Last reviewed: July 2019

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 modified 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. The evaluation of code outcomes  notes that the state is on track to achieving these goals, 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”.

Last reviewed: June 2020

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