Accessing the Illinois Energy Conservation Code

The Illinois Energy Conservation Code (referred to as “the Code”) is the State of Illinois' official building energy code and is based on the 2018 International Energy Conservation Code (IECC), with Illinois Amendments. The City of Chicago has made further amendments. 

The Code can be accessed here: 

The 2018 International Energy Conservation Code was adopted July 1, 2019.

Please see our Frequently Asked Questions(FAQ's) concerning the 2018 International Energy Conservation Code (IECC), with Illinois amendments and relevant referenced Standards therein, as they apply to the State of Illinois.

See also our glossaries of important energy conservation code terms:

Illinois Baseline Compliance Study – Measuring the Baseline Compliance with Residential and Non-Residential Buildings in Illinois against the 2009 & 2012 International Energy Conservation Code

Illinois resources for builders and code officials

DOE’s Building Energy Codes Program Compliance Software Tools

  • REScheck. Used to show compliance on residential building plans
  • COMcheck. Used to show compliance on commercial building plans
  • Other forms of compliance may be used as approved by the authority having jurisdiction
  • USDOE’s Building Energy Codes Program Help Desk. People can submit technical questions about building energy codes, or ask for assistance with REScheck or COMcheck applications. 

SEDAC's Energy Code Publications

Other Resources

  • Illinois Consumer Checklist. This checklist is designed to help you spot check for compliance with the Illinois Energy Conservation Code. While it does not include every requirement, this checklist will help you assess a home and make an informed decision about the quality of construction and efficiency of a home.
  • Illinois Consumer Guide. This guide provides a quick way to assess home energy performance.The guide describes the minimum standards of construction practice for new homes in Illinois based on the 2012 International Energy Conservation Code(IECC) with amendments as the Illinois Energy Conservation Code.While it does not include every requirement, this will help you assess your own home, and if you are in the market for a new home, make an informed decision about the quality of construction and efficiency for that new home purchase.
  • US DOE’ s Building America Solution Center. The Solution Center provides access to expert information on hundreds of high-performance construction topics, including air sealing and insulation, HVAC components, windows, indoor air quality, and much more.