Illinois Energy Conservation Code

The Illinois Energy Conservation Code requires design and construction professionals to follow the latest published edition of the International Energy Conservation Code (IECC) and the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 90.1 "Energy Standard for Buildings except Low-Rise Residential Buildings" including amendments adopted by the Capital Development Board.

State Funded Facilities must comply with the IECC per 20 ILCS 3125.  See Subpart B of the Illinois Energy Conservation Code for more information.  The 2018 edition of the IECC went into effect on 7/1/19.

Privately Funded Commercial Facilities must comply with IECC per 20 ILCS 3125.  See Subpart C of the Illinois Energy Conservation Code for more information. The 2018 edition of the IECC went into effect on 7/1/19.

Residential Buildings must comply with IECC per 20 ILCS 3125. See Subpart D of the Illinois Energy Conservation Code for more information. The 2018 edition of the IECC went into effect on 7/1/19.

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

Updates to the Illinois Energy Conservation Code


CDB is accepting applications for the Illinois Energy Conservation Advisory Council.  The positions are for representatives of the residential construction contracting industry.  For more information click here.