(20 ILCS 3125/20)
    Sec. 20. Applicability.
    (a) The Board shall review and adopt the Code within one year after its publication. The Code shall take effect within 6 months after it is adopted by the Board, except that, beginning January 1, 2012, the Code adopted in 2012 shall take effect on January 1, 2013. Except as otherwise provided in this Act, the Code shall apply to (i) any new building or structure in this State for which a building permit application is received by a municipality or county and (ii) beginning on the effective date of this amendatory Act of the 100th General Assembly, each State facility specified in Section 4.01 of the Capital Development Board Act. In the case of any addition, alteration, renovation, or repair to an existing residential or commercial structure, the Code adopted under this Act applies only to the portions of that structure that are being added, altered, renovated, or repaired. The changes made to this Section by this amendatory Act of the 97th General Assembly shall in no way invalidate or otherwise affect contracts entered into on or before the effective date of this amendatory Act of the 97th General Assembly.
    (b) The following buildings shall be exempt from the Code:
        (1) Buildings otherwise exempt from the provisions of
a locally adopted building code and buildings that do not contain a conditioned space.
        (2) Buildings that do not use either electricity or
fossil fuel for comfort conditioning. For purposes of determining whether this exemption applies, a building will be presumed to be heated by electricity, even in the absence of equipment used for electric comfort heating, whenever the building is provided with electrical service in excess of 100 amps, unless the code enforcement official determines that this electrical service is necessary for purposes other than providing electric comfort heating.
        (3) Historic buildings. This exemption shall apply
to those buildings that are listed on the National Register of Historic Places or the Illinois Register of Historic Places, and to those buildings that have been designated as historically significant by a local governing body that is authorized to make such designations.
        (4) (Blank).
        (5) Other buildings specified as exempt by the
International Energy Conservation Code.
    (c) 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. The following need not comply with the Code, provided that the energy use of the building is not increased: (i) storm windows installed over existing fenestration, (ii) glass-only replacements in an existing sash and frame, (iii) existing ceiling, wall, or floor cavities exposed during construction, provided that these cavities are filled with insulation, and (iv) construction where the existing roof, wall, or floor is not exposed.
    (d) A unit of local government that does not regulate energy efficient building standards is not required to adopt, enforce, or administer the Code; however, any energy efficient building standards adopted by a unit of local government must comply with this Act. If a unit of local government does not regulate energy efficient building standards, any construction, renovation, or addition to buildings or structures is subject to the provisions contained in this Act.
(Source: P.A. 102-662, eff. 9-15-21.)