Frequently Asked Questions

Note: The responses to the questions below are based on the Illinois Energy Conservation Code. SEDAC is the Energy Code Training Provider for Illinois EPA and is not the code official nor the authority having jurisdiction. As such, the opinions expressed below are advisory and not a legal interpretation. 

"The Code" or "the Energy Code" refers to the current Illinois Energy Conservation Code, which is based on the 2018 IECC with Illinois Amendments. Section numbers are from the 2018 IECC. 

Administration/Legal Questions

Q: When did the updated Illinois Energy Code based on the 2018 IECC become effective? 
A: The Illinois Energy Code based on the 2018 IECC with Illinois Amendments became effective 7/1/2019. For the City of Chicago, the updated Energy Code based on the 2018 IECC became effective on 6/1/2019. 

Q: How do I know which version of the Illinois Energy Code my project is required to follow?
A: 
The code version is generally determined by the date of the permit application. For permits in Illinois, all permits submitted after 7/1/2019 must comply with the 2018 IECC version. For permits in Chicago, all permits submitted after 6/1/2019 must comply with the 2018 IECC version. Ultimately, the Authority Having Jurisdiction has the final say on which version to use, so check with your local Authority Having Jurisdiction to verify the version for your project. 

Q: Can I use both ASHRAE 90.1 and IECC for Energy Code compliance? 
A:
Projects must choose one compliance path for minimum Energy Code Compliance. Designers are not permitted to "cherry-pick" a customized path to compliance by combining provisions of both ASHRAE Standard 90.1 and IECC 2018. Either code must be used in its entirety with applicable Illinois Amendments. Projects may choose to go beyond minimum code compliance, but minimum code compliance must be demonstrated using a single compliance path. 

Q: I am working on an elementary school. Who is the Authority Having Jurisdiction for code enforcement?
A:
According to Title 23 of the Illinois Administrative Code Part 180 Health/Life Safety Code for Public Schools, the Authority Having Jurisdiction is the Regional Superintendent. 

Q: I have a mixed-use building. How do I determine which provisions (residential or commercial) apply?  
A: [C101.4.1, R101.4.1] For mixed residential and commercial buildings 3 stories or less (4 or less in Chicago), each portion must separately consider and meet the applicable commercial or residential provisions. Mixed residential and commercial buildings larger than three stories (four in Chicago) are considered commercial buildings, and residential portions of these larger buildings do not need to meet separate residential provisions.  

Commercial Questions

Q: How might the Energy Code apply to a proposed building without heating and cooling? 
A: [600.310]
If the building does not "contain conditioned space," it does not need to comply with the Illinois Energy Conservation Code. Be aware that if the building is changed in the future and no longer qualifies as a low-energy building, it may require substantial work to bring the envelope into compliance (See Title 71 Section 600.310 of the IL Administrative Code).  

Q: Is daylight harvesting and daylight zone control required by the Energy Code? 
A: [C405.2.3] Yes, if there are more than 150 watts of general lighting in the sidelit or toplit zone. There are some exceptions provided for certain applications. For instance, areas are exempt from meeting the daylight zone control requirements if the area weighted lighting power density is less than 40% of normal LPD for the space type (Exemption #4, see also C406.3).

Q: For a low slope roof replacement, what should be done if there is not enough room to provide the full R-30 insulation and install flashings properly? 
A: [C503.1, C402.1]
Complying with requirements for alterations does not "require unaltered portions of the existing building to comply with the code" or "create unsafe or hazardous conditions or overload existing building systems." This suggests that the amount of insulation should be brought as close to the level required by the Code, while accounting for restrictions of existing conditions (parapet walls, equipment curbs, fenestration, etc.) and manufacturer's flashing installation directions. The level of insulation after the roof replacement may not be less than what it was before the roof replacement.
In addition, there is an Illinois Amendment which covers "roof membrane peel and replacement." When the membrane is removed and replaced with no insulation work or roof deck work done, this would not require the roof insulation to be increased. However, not inspecting the roof deck may not follow the recommended practices of the National Roofing Contractors Association. It is recommended that the feasible additional insulation be planned in the project rather than rebidding if insulation or roof deck repairs are needed.
 

Residential Questions

Q: What is a "low-energy" building per the Energy Code?
A: [R402.1].
A low-energy building is a building that has a peak design rate of energy usage less than 3.4 Btu/h ft2 or 1.0 W/sf of floor area for space-conditioning purpose. A building that does not contain conditioned space is a low-energy building. 

Q: What are the air sealing/air barrier requirements for rim joists?
A: [Table R402.4.1.1]. 
Rim joists should include the air barrier and insulation, and the air barrier should be continuous per Table R402.4.1.1. Air-permeable insulation, such as fiberglass, should not be used as a sealing material. Components fo the building envelope should be installed according to the manufacturer's instruction.

Q: What is the maximum air leakage rate allowed per Code?
A: [R402.4.1.2] 
Per Illinois Amendments, the Code requires buildings to be tested and verified as having an air leakage rate not exceeding 4 air changes per hour (ACH). The building should be provided with a whole-house mechanical ventilation system as designed in accordance with Section R403.6. Air leakage testing should be conducted in accordance with ASTM E779 or ASTM E1827 and reported at a pressure of 50 pascals. 

Q: Is diagnostic testing required for assessing compliance with the Energy Code? 
A: [R402.4.1.2] 
Yes. The air leakage testing called for in Section R402.4.1.2 will require diagnostic testing equipment such as a blower door to be used for compliance verification. This is a mandatory provision of the code and therefore is required regardless of the compliance path chosen. 

Q: Are permits required for window replacements? 
A: Permit requirements vary by jurisdiction. Check with your local jurisdiction to determine their permit requirements. 

Q: If I open a wall, do I need to add the required amount of insulation if there isn't enough space?
A: [R503.1.1] Building envelope assemblies that are part of the alteration are required to follow certain envelope requirements, including insulation requirements, but there are a number of exceptions. Exception 2 would likely apply to this situation: "Existing ceiling wall or floor cavities exposed during construction" do not need to comply with these requirements "provided that the energy use of the building is not increased" and "provided that these cavities are filled with insulation." Thus, the wall would not need to be expanded to add R-20 insulation, but it would require insulation to fill the cavity. R-13 or R-15 insulation would likely be sufficient for a 2X4 wall. 

Note that for masonry walls, an air gap should be left between the masonry and the wall/insulation because masonry absorbs water and needs to be able to dry or it will degrade. Leaving no air gap would violate the requirement that "alterations shall not create an unsafe or hazardous condition or overload existing building systems" (R503.1). 

Q: For a low slope roof replacement, what should be done if there is not enough room to provide the full R-30 insulation and install flashings properly? 
A: [R503.1]
Code compliance for alterations does not "require unaltered portions of the existing building to comply with the code" or "create unsafe or hazardous conditions or overload existing building systems." This suggests that the amount of insulation should be brought as close to the level required by the Code, while accounting for restrictions of existing conditions (parapet walls, equipment curbs, fenestration, etc.) and manufacturer's flashing installation directions. The level of insulation after the roof replacement may not be less than what it was before the roof replacement. 

In addition, there is an Illinois Amendment which covers "roof membrane peel and replacement." When the membrane is removed and replaced with no insulation work or roof deck work done, this would not require the roof insulation to be increased. However, not inspecting the roof deck may not follow the recommended practices of the National Roofing Contractors Association. It is recommended that the feasible additional insulation be planned in the project rather than rebidding if insulation or roof deck repairs are needed.