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.

Links to referenced codes can be found here.

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 2021 IECC became effective on 11/1/2022.

Q: When will the updated Illinois Energy Code based on the 2021 IECC become effective? 
A: The Illinois Energy Code based on the 2021 IECC with Illinois Amendments is expected to become effective in 2023.

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 on or after 11/1/2022 must comply with the 2021 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 to demonstrate 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 (for example 90.1 for HVAC and IECC for lighting would not be permitted). Either code must be used in its entirety with applicable Illinois Amendments to demonstrate compliance. Projects may choose to go beyond minimum code compliance, but 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 above grade (4 or less in the City of 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 the City of Chicago) are considered commercial buildings, and residential portions of these larger buildings do not need to meet separate residential provisions unless referenced in the commercial 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 undergoes a change of use and/or is conditioned 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: We are working on a 45,000 square foot unoccupied tenant space in IL, to be turned over as a "cold dark shell" ready for tenant build-out. As part of the work, we are installing a new 230 square foot loading dock. Is the new loading dock required to be insulated?
A: [C402.1.1, C402.5.6] The loading dock may qualify as a low-energy building (or portion thereof) (see C402.1.1), which would exempt it from needing to be insulated. The loading dock would need to be thermally separated from the remainder of the building unless the whole building qualifies as a low-energy building. This may impact future use or make build out more expensive if a future client desires heat. It would then no longer qualify as a low-energy building and require insulation.  If the loading dock does not qualify as a low-energy building (or portion thereof), it is required to follow C402 of the 2015 IECC including C402.5.6 (Loading dock weatherseals).

Q: Where do I find design conditions for my project?
A: [C403.1.1] ASHRAE has a Climatic Design Conditions Tool which may be found here. Select the most recent data at the top of the page and the nearest site to your project location for the most accurate data, including heating and cooling design conditions.

Q: Are you permitted to install occupancy sensors in a stairway or public corridor? 
A: Maybe. This question is not addressed in the 2018 IECC; instead, please check the safety requirements of other local and national codes that have jurisdiction over the project. Some relevant safety codes include the Chicago Building Code, the 2018 IBC, and the Life Safety Code (NFPA 101). We reviewed these codes and found that generally you can have energy saving motion sensors for lighting in designated egress zones, as long as they meet certain safety requirements. For instance, you are not required to illuminate paths of egress in normally unoccupied areas of the building or service support areas. Therefore, support areas may be great places to take advantage of motion sensitive lighting controls. Your local AHJ or planning office may have additional guidance.

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: I am renovating a commercial building. Do I need to bring my building's envelope up to full compliance with the 2018 IECC? 
A: [C502, C503 & C505.1]. If a space changes occupancy or use that would increase the demand for fossil fuel or electrical energy, the space must meet the 2018 IECC envelope requirements. For example, if a warehouse storage area is converted into an office space or a warehouse is converted into residential lofts, these spaces must be insulated to the current energy code. If part of a building is altered or new construction is added to the building, the altered or added parts of the building must comply with envelope requirements. The code requirements do not apply to the unaltered parts of the building.

Q: When I'm doing roof work, when do I need to add insulation?
A: [C503.3.1, C504]. There are several kinds of roof work. Some of them trigger compliance with the IECC envelope requirements, some do not.

• Roof replacement is defined as the process of "removing the existing roof covering, repairing any damaged substrate and installing a new roof covering." During roof replacements, section C503.3.1 requires the roof deck to be brought into compliance with the IECC thermal envelope requirements if "the existing roof assembly is part of the building thermal envelope and contains insulation entirely above the roof deck." Roof replacement presents a unique opportunity to add insulation. We strongly recommend that you meet or exceed the minimum insulation requirements, if feasible. Most roof membrane replacements will fall into this category due to the practice of repairing damaged substrate or insulation. Projects should plan to insulate the amount feasible as discussed below. Given the passivity of insulation, exceeding the minimum level will provide additional value for years to come. See below if there is not adequate room to provide the insulation called for.
• Roof membrane peel and replacement is defined as removing the existing membrane and installing a new membrane, but not replacing any roof decking or insulation. This type of roof work is currently exempt from the envelope requirements (see Illinois Amendments).
• Roof recover is defined as "the process of installing an additional roof covering over a prepared existing roof covering without removing the existing roof covering." Section C503.1 indicates that roof recovers are not required to meet the IECC insulation and envelope requirements.
• Roof repairs are defined as "reconstruction or renewal of any part of an existing roof for the purposes of its maintenance." These are also exempt from meeting the IECC insulation and envelope requirements (C504).

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.

Q: Can you provide clarification on recirculating pumps for lavatories on a small commercial project? Do you need to install them if the bathrooms in the facility are not being replaced? I also saw that a thermostatic mixing valve needs to be within a short distance of the faucet. Does this pertain if there is a recirculation pump?
A: [C503.5] C503.5 explains that new service hot water systems that are part of the alteration must comply with C404 (Service water heating). C404.5.1 identifies the maximum allowable piping length from the nearest source of heated water. The objective is to allow heated water to be available in a reasonable period of time and avoid running the water while waiting for heated water, particularly as efficient fixtures become the norm. New lavatory faucets with 0.5 gpm flow rates are only flowing about 1 ounce per second.  Meeting the maximum piping length may be achieved in several different ways, such as through a circulated loop or a point-of-use heater. If a circulated loop is used, C404.6 would come into play for the heated water circulating or temperature maintenance system. Additional information on circulating systems may be found in this Smart Tip.

Residential Questions

Q: Where do I find design conditions for my project?
A: [R403.7] ASHRAE has a Climatic Design Conditions Tool which may be found here. Selecting the most recent data at the top of the page and the nearest site to your project location will provide the most accurate data including heating and cooling design conditions.

Q: What are the air sealing/air barrier requirements for rim joists?
A: [Table R402.4.1.1]. Rim joists should include an 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 of 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. Low-rise multi-family buildings have an alternative testing method in the Illinois Amendments.

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 an exterior wall, what do I do if there isn't enough depth to insulate to current code? 
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: I am renovating a house but not changing space conditioning requirements; what envelope requirements must I meet?
A: [R503.1.1]. If your renovation is not changing occupancy or increasing the energy use of the space, you are often not required to bring the existing portions of the building into compliance with the 2018 IECC envelope requirements in section R402. When a floor, wall or ceiling cavity is opened in the process of a renovation that portion of the envelope is not required to be brought up to the new construction insulation level as long as the cavity is filled with insulation, and the renovation is not changing space conditioning requirements. If the cavity is not filled with insulation, the 2018 IECC requires that you add it.

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.

Q: Does a basement with interior blanket insulation still meet the requirements for continuous insulation if the electrical panel penetrates the insulation to mount to the wall or the blanket is interrupted for intersecting walls?
A: For insulation to qualify as continuous, it must be a layer of insulation uninterrupted by framing members or penetrations except for service openings and fasteners. The electrical panel or intersecting walls does not qualify as a service opening, and this would require insulation behind it for the insulation to qualify as continuous.