Illinois Energy Conservation Code

Solar panelsThe 2015 IECC became effective in Illinois on January 1, 2016

In accordance with the Energy Efficient Building Act, the Capital Development Board (CDB) is required to review and adopt the most current version of the International Energy Conservation Code (IECC) within one year of its publication date. The Code will then become effective in Illinois within 6 months following its adoption by the CDB. The CDB, in conjunction with the Department of Commerce & Economic Opportunity (DCEO), updated the 2012 International Energy Conservation Code (IECC) to the 2015 IECC, and the 2015 IECC, with Illinois Amendments, became law in the State of Illinois on January 1, 2016. 

On July 1, 2017, Illinois Executive Order 17-03 transferred responsibility for the Illinois Energy Conservation Code from the Illinois Department of Commerce and Economic Opportunity to the Illinois Environmental Protection Agency (IEPA).

The Illinois Energy Conservation Code can be accessed here: 

2018 IECC is anticipated to be effective in May, 2019

The Capital Development Board (CDB), in conjunction with the Illinois Environmental Protection Agency and the Illinois Energy Conservation Advisory Council, has initiated the cycle for the Illinois Energy Conservation Code to update from the 2015 International Energy Conservation Code (IECC) to the 2018 IECC. It is anticipated at this time that the updated Illinois Energy Conservation Code based on the 2018 IECC and Illinois Amendments will be effective on May 1, 2019. 

You can access the 2018 International Energy Conservation Code here and learn about the 2018 IECC updates in SEDAC's workshops and webinars.  

What the law requires

The law requires all new commercial and residential construction for which a building permit application is received by a municipality or county to follow a comprehensive statewide energy conservation code. Renovations, alterations, additions, and repairs to most existing commercial and residential buildings must follow the Illinois Energy Conservation Code. The Law requires design and construction professionals to follow the latest published edition of the International Energy Conservation Code (IECC) which is currently the 2015 IECC and the ASHRAE Standard 90.1-2013 “Energy Standard for Buildings except Low-Rise Residential Buildings,” referenced therein. Under the law, the Capital Development Board has the power to modify the Illinois Energy Conservation Code. 

Local governments are free to adopt stricter energy conservation laws for commercial buildings defined by the law. However, for residential buildings defined by the law, local governments may not adopt or regulate energy conservation standards either less or more stringent than the Illinois Energy Conservation Code. Exceptions which would allow local governments to regulate energy efficient standards in a more stringent manner are municipalities or counties which meet one of the following three provisions:

  • A unit of local government that on or before May 15, 2009 adopted or incorporated by reference energy efficient building standards for residential building that are equivalent to or more stringent than the 2006 International Energy Conservation Code
  • A unit of local government that on or before May 15, 2009 provided to the Capital Development Board identification of an energy efficient building code or amendment that is equivalent to or more stringent than the 2006 International Energy Conservation Code
  • A municipality with a population of 1,000,000 or more

The goals of the law

The law is designed to help protect the environment and reduce energy consumption. By following an energy conservation code, property owners can reduce air pollution, moderate energy demand and stabilize energy costs and electric, oil, and gas supplies.

The efficiency gains of the 2009 IECC set a new baseline for International Energy Conservation Code-compliant, new single-and multifamily homes, and while, there will be regional variability and uncertainty in technology penetration, quantitative estimates of National Energy & Cost Savings for New Single-and Multifamily Homes from U.S.DOE concluded that moving from a baseline of the 2006 IECC to the 2009 IECC reduces average annual energy costs by 10.8%, while moving from the same baseline 2012 IECC reduces them by 32.1% .In its May 2015 report entitled 2015 IECC: Energy Savings Analysis, the U.S.DOE concludes that new single-and multifamily homes built to the 2015 IECC, compared with buildings built to the 2012 IECC, would result in an energy cost savings of approximately 0.82-0.63 percent for Illinois Climate Zones 4 and 5. In its June 2015 report entitled Energy and Energy Cost Savings Analysis of the 2015 IECC for Commercial Buildings, the U.S.DOE concludes that new commercial buildings built to the 2015 IECC, compared with buildings built to the 2012 IECC, would result in an energy cost savings of 11.5 percent on a national aggregated basis.

What the law doesn't cover

The law does not apply to buildings designated “historic” or having “landmark status” (interior and exterior separately), buildings exempt from a local building code, and buildings that do not use either electricity or fossil fuel for comfort conditioning. For purposes of determining whether this exemption applies, a building will be presumed to be heated by electricity, even in the absence of equipment used for electric comfort heating, whenever the building is provided with electrical service in excess of 100 amps. The Illinois’ Energy Efficient Building Act may be found in Chapter 20 of the Illinois Compiled Statutes, Act 3125.