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Illinois Energy Codes

Illinois Energy Conservation Code (20 ILCS 3125/15)

The Illinois Energy Conservation Code requires design and construction professionals to follow the latest published edition of the International Energy Conservation Code (IECC) including amendments adopted by CDB for all commercial and residential buildings in the State.


*****Attention Municipalities!*****

The 2021 Illinois Energy Conservation Code print and electronic editions are coming soon! The code will be publicly available online via the International Code Council website ( and printed code books for purchase beginning summer 2024.

The Smart Energy Design Assistance Center (SEDAC) at the University of Illinois as the Illinois Energy Code Technical Support Provider is finalizing mailings to all municipalities with information about how to receive one (1) free printed code book and resources available for training on the energy code. Code Officials and local government representatives with questions about the code are encouraged to reach out to SEDAC  

Illinois Stretch Energy Code (20 ILCS 3125/55)

The Illinois Stretch Energy Code (currently in development) allows municipalities and projects authorized or funded by the Board to achieve more energy efficiency in buildings than the Illinois Energy Conservation Code through a consistent pathway across the State.

Additional information including training opportunities, interpretations and frequently asked questions can be found on the Illinois Environmental Protection Agency's website.

Upcoming Training Opportunities for Illinois Energy Codes are being provided by the Smart Energy Design Assistance Center.  For more information, please use the following link:

2025 Illinois Stretch Energy Code Technical Advisor RFP  The State of Illinois Capital Development Board intends for development of the 2025 Illinois Stretch Energy Code.  The Board issues a Request for Proposal from qualified firms to serve as the 2025 Illinois Stretch Energy Code Technical Advisor.  The successful firm will be responsible for providing technical assistance to the CDB and the Illinois Energy Conservation Advisory Council to develop, evaluate, and assess energy efficiency and emissions reducing measures into the State’s Stretch Energy Code.


Illinois Energy Conservation Advisory Council Members

Contact Information

Robert Coslow
Phone: 217-685-4079
TDD: 217-524-4449