2015 IECC with Amendments - Residential Building code (Illinois)

Last updated: 25 February 2019
Projects shall comply with one of the following:
1. Sections R401 through R404.
2. Section R405 and the provisions of Sections R401 through R404 labelled "Mandatory."
3. An energy rating index (ERI) approach in Section R406.
Building Thermal Envelope
The building thermal envelope shall meet the requirements of Sections R402.1.1 through R402.1.5.
Specific Insulation Requirements (Prescriptive)
In addition to the requirements of Section R402.1, insulation shall meet the specific requirements of Sections R402.2.1 through R402.2.13.
Fenestration (Prescriptive)
In addition to the requirements of Section R402, fenestration shall comply with Sections R402.3.1 through R402.3.5.
Air Leakage (Mandatory)
The building thermal envelope shall be constructed to limit air leakage in accordance with the requirements of Sections R402.4.1 through R402.4.4.
Windows, skylights and sliding glass doors shall have an air infiltration rate of no more than 0.3 cfm per square foot (1.5 L/s/m2), and swinging doors no more than 0.5 cfm per square foot (2.6 L/s/m2), when tested according to NFRC 400 or AAMA/WDMA/CSA 101/I.S.2/A440 by an accredited, independent laboratory and listed and labeled by the manufacturer.
Service Hot Water Systems
Energy conservation measures for service hot water systems shall be in accordance with Sections R403.5.1 through R403.5.4.
Lighting Equipment (Mandatory)
Not less than 75 percent of the lamps in permanently installed lighting fixtures shall be high-efficacy lamps or not less than 75 percent of the permanently installed lighting fixtures shall contain only high-efficacy lamps.
Energy Rating Index
The Energy Rating Index (ERI) shall be a numerical integer value that is based on a linear scale constructed such that the ERI reference design has an Index value of 100 and a residential building that uses no net purchased energy has an Index value of 0. Each integer value on the scale shall represent a 1-percent change in the total energy use of the rated design relative to the total energy use of the ERI reference design. The ERI shall consider all energy used in the residential building.
Existing Buildings
Additions, alterations, or repairs to an existing building, building system or portion thereof shall comply with Section R502, R503 or R504. Unaltered portions of the existing building or building supply system shall not be required to comply with this code.
Except as specified in this chapter, this code shall not be used to require the removal, alteration or abandonment of, nor prevent the continued use and maintenance of, an existing building or building system lawfully in existence at the time of adoption of this code.
Amendements below include but not limited to:
Tables R402.1.2 Insulation/Fenestration and R402.1.4
Amended as follows –
Climate Zone 4: SHGC not required, 2015 IECC requires 0.40
Climate Zone 5: Basement Wall Insulation 10/13, 2015 IECC requires 15/19
Basement Wall Total U-factor 0.059, 2015 IECC requires 0.050
R402.2.9 Basement walls. Walls associated with conditioned basements shall be insulated from the top of the basement wall down to 10 feet (3048 mm) below grade or to within six-inches (152 mm) of the basement floor, whichever is less. Walls associated with unconditioned basements shall meet this requirement unless the floor overhead is insulated in accordance with Sections R402.1.2 and R402.2.8.

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