Illinois Building Energy Codes

Code Level


Authorized by – Statute. 2009's Energy Efficient Building Act modified the previous Energy Efficient Commercial Building Act to require the latest version of the IECC as the building energy code for both commercial and residential buildings. The statute is found at 20 ILCS 3125. Administrative rules for the Illinois Energy Conservation Code are found at 71 IAC 600.

Oversight – The building codes, including the energy code, are overseen by the Capital Development Board, and more specifically by the CDB's Division of Building Codes & Regulations. The Illinois Energy Code Advisory Council meets regularly to evaluate energy code issues and provide advice to the board.

Code change process Regulatory and Legislative.  The Capital Development Board reviews and adopts the latest model code within a year of its release. The rule adopting the new code must then be approved by the General Assembly's Joint Committee on Administrative Rules (JCAR).

Code change cycle - Every 3 years, concurrent with updates to the model energy code.


Enforcement - The Capital Development Board, along with the Department of Commerce and Economic Opportunity are responsible for defining compliance procedures. Code enforcement is the duty of the local jurisdiction, who must meet minimum compliance documentation requirements.

Implementation/Compliance Studies – The Illinois Department of Commerce and Economic Opportunity conducted a residential and commercial building energy code baseline compliance study in 2014. Click here for a full report.


The Illinois Energy Codes Compliance Collaborative first met in 2017 and has reconvened starting in May 2018. Click here to learn more about the collaborative or visit the Illinois Energy Codes Compliance Collaborative Website for more details. 

Primary Contacts

Illinois EPA Office of Energy

Illinois Capital Development Board

Illinois Association of Code Enforcement

Illinois Council of Code Administrators

Smart Energy Design Assistance Center (SEDAC)