Section 600.110  Adoption and Modification of the Illinois Energy Codes

a)         The purpose of the Illinois Energy Conservation Code is to implement Section 15 of the Energy Efficient Building Act [20 ILCS 3125] that requires CDB to officially adopt, as a minimum requirement for commercial structures and as a minimum and maximum requirement for residential buildings, the 2021 International Energy Conservation Code, including all published errata but excluding any published supplements, to apply that Illinois Energy Conservation Code to all commercial and residential structures in Illinois, and to assist local code officials with enforcing the requirements of the Illinois Energy Conservation Code. The 2021 Illinois Energy Conservation Code will become effective on January 1, 2024.

b)         The purpose of the Illinois Stretch Energy Code as described in Subparts B, C, and D (State facilities, privately-funded commercial facilities and residential buildings) is to implement Section 55 of the Energy Efficient Building Act [20 ILCS 3125] that requires CDB to officially adopt, as a minimum requirement for State facilities, commercial structures and residential buildings in municipalities that have adopted the Illinois Stretch Energy Code, an energy code that meets the site energy indexes as outlined in Section 55 of the Energy Efficient Building Act.

c)         The Illinois Energy Conservation Code as described in Subpart C (privately-funded commercial facilities) is effective April 8, 2007. The Illinois Energy Conservation Code as described in Subpart D (residential buildings) is effective January 29, 2010.  The Illinois Stretch Energy Code as described in Subparts B, C and D (State facilities, privately-funded commercial facilities and residential buildings) is effective January 1, 2025.

d)         Application of the Codes

1)         State Facilities.  The Illinois Commercial Stretch Energy Code as described in Subpart B of this Part applies to all projects to which an energy conservation code is applicable that are authorized or funded in any part by the Board after July 1, 2024.  [20 ILCS 3125/55]

2)         Privately Funded Commercial Facilities and Residential Buildings.  The Illinois Energy Conservation Code or the Illinois Stretch Energy Code if adopted by the local municipality as described in Subparts C and D of this Part applies to any new building or structure in this State for which a building permit application is received by a municipality or county.  [20 ILCS 3125/20] 

A)        Additions, alterations, renovations, or repairs to an existing building, building system or portion thereof shall conform to the provisions of the Code as they relate to new construction without requiring the unaltered portion of the existing building or building system to comply with the Code.  [20 ILCS 3125/20(c)]

B)        All exceptions listed in the Code related to additions, alterations, renovations, or repairs to an existing building are acceptable provided the energy use of the building is not increased.

e)         This Code, together with the standards incorporated by reference in this Part, has the force of a building code and is administrative law applicable in the State of Illinois.

(Source:  Amended at 48 Ill. Reg. 14276, effective January 1, 2025)