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 its own energy efficiency code, which is also based on the 2018 IECC, with Illinois Amendments and Chicago Amendments included. The Code versions can be accessed here:

• 2018 International Energy Conservation Code
• Illinois Amendments
• 2019 Chicago Energy Conservation Code

The State of Illinois adopted the 2018 International Energy Conservation Code on July 1, 2019 in Illinois. Please see our Frequently Asked Questions (FAQs) concerning the 2018 IECC, with Illinois amendments and relevant referenced Standards therein, as they apply to the State of Illinois.

DOE’s Building Energy Codes 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
• US DOE’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

Resources for builders and code officials

• Building Energy Codes Resource Guide: Code Officials Edition. U.S. Department of Energy
• HVAC Controls Guide for Plan Examiners and Building Inspectors. U.S. Department of Energy

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.