Codes of Record

International Energy Conservation Code, commercial

Illinois enforces the 2024 IECC commercial

The 2024 International Energy Conservation Code (IECC) for commercial buildings has been in force in Illinois since Nov 30, 2025. It applies statewide. Adopted by Capital Development Board. The legal citation is 71 Ill. Adm. Code 600.300; 20 ILCS 3125/15.

Record of adoption

Edition in force

2024 IECC

Illinois Energy Conservation Code (2024)

Verified

In force since
Legal citation
71 Ill. Adm. Code 600.300; 20 ILCS 3125/15
Adopted by
Capital Development Board
Second reading
Applies
Statewide
Also called
ILECC, 2024 ILECC, 71 Ill. Adm. Code 600

Appendix amendments reference ASHRAE 90.1-2022 within the 2024 IECC commercial path; Section 600.100 definitions still say 2021.

Exceptions

  • Chicago enforces its own Chicago Energy Transformation Code (based on the 2021 IECC, eff. Nov 1, 2022)

Coming next

  • Edition not knownPartial
    No date yetIn development20 ILCS 3125/55; P.A. 104-0315 (HB 3510)

    CDB page lists 2026 Stretch Energy Code proposals. HB 3510 (P.A. 104-0315, eff. Jan 1, 2026) moved the stretch-code adoption deadlines. This is an optional overlay, not the next base edition. No next base-code edition (2027 IECC) adoption found.

How Illinois adopts the IECC commercial

  • Agency rule
  • The legislature reviews the rules and can block them
  • A recent law changed the process

The Capital Development Board, in consultation with the Agency named in the Act, adopts the Illinois Energy Conservation Code by administrative rule (71 Ill. Adm. Code 600), incorporating a model IECC edition with Illinois amendments. Rules go through JCAR review, which can object or prohibit filing. The legislature set the Board as adopter and set deadlines for the optional Stretch Energy Code, most recently changed by P.A. 104-0315.

Cycle. Agency-initiated, roughly every three years following the IECC cycle (per a University of Illinois EnergySense page)

Laws, rulings, and other actions

  1. Legislation
    P.A. 104-0315 (HB 3510, 104th General Assembly)

    Amends the Energy Efficient Building Act’s Illinois Stretch Energy Code provisions, changing adoption dates for stretch-code targets.

    Enacted Aug 15, 2025, effective Jan 1, 2026

    ilga.gov (opens in a new tab)
  2. Legislation
    SB 2491 (104th General Assembly)

    Would change stretch-code adoption deadlines in the Energy Efficient Building Act.

    Pending; last action Jun 2, 2025, re-referred to Assignments (superseded in substance by HB 3510)

    my.ilga.gov (opens in a new tab)
  3. Other action
    Chicago Energy Transformation Code effective

    Chicago’s energy code, based on the 2021 IECC, took effect for city permits.

  4. Legislation
    P.A. 102-444, 102-662, 102-813 (102nd General Assembly)

    Listed in the source note of 20 ILCS 3125/15 as amending the Board’s energy-code adoption section.

    Enacted, effective Aug 20, 2021, Sep 15, 2021, and May 13, 2022

    ilga.gov (opens in a new tab)
  5. UndatedLegislation
    HB 4994 (104th General Assembly)

    Would let counties as well as municipalities adopt the Illinois Stretch Energy Code.

    Pending; shown as Introduced

    my.ilga.gov (opens in a new tab)

How it was checked

Verified

Two separate readings of the state’s own record agree, and the passage is on file word for word.

Read twice: a second, blind reading of the state’s record agreed with the first on .

The state’s record was last read on , from five source pages.

Evidence 4 sources

Sources for the record itself come first, the state’s own records ahead of others. A label marks a source about something else, such as an exception. A source marked secondary is not the state’s own record.

  • “The 2024 IECC, including published errata”

    “as applicable to privately funded commercial facilities”

    “(Source: Amended at 49 Ill. Reg. 15562, effective November 30, 2025)”

    Section 600.300 Illinois Energy Conservation Code (commercial)Illinois General Assembly, Joint Committee on Administrative Rulesilga.gov (opens in a new tab)Administrative codeRetrieved

  • “excluding published supplements that encompass ASHRAE 90.1-2022”

    Illinois Energy Conservation Code Amendments to the 2024 International Energy Conservation CodeIllinois General Assembly, Joint Committee on Administrative Rulesilga.gov (opens in a new tab)Administrative codeRetrieved

  • About a coming change

    Illinois Energy CodesIllinois Capital Development Boardcdb.illinois.gov (opens in a new tab)Agency pageRetrieved

  • Background

    Section 600.100 DefinitionsIllinois General Assembly, Joint Committee on Administrative Rulesilga.gov (opens in a new tab)Administrative codeRetrieved

Tracker cross-checks

Code adoption trackers are a cross-check. They are not Illinois’s own record.

  • About a tracker cross-check

    Illinois State Code StatusCross-checkUS Department of Energy, Building Energy Codes Programenergycodes.gov (opens in a new tab)Tracker, secondaryRetrieved

  • DOE’s energycodes.govCross-checkAgrees with the record

    Commercial: 2024 IECC and ASHRAE 90.1-2022; State Amendments: Yes; Effective Date: 11/30/2025; Mandatory Statewide

    energycodes.gov (opens in a new tab)Read

  • ICC’s code adoption mapCross-checkAgrees with the record

    24 (2024 IECC adopted); chart as of 2026-04

    mitek-us.com (opens in a new tab)Read

Related pages

Other codes in Illinois