Illinois implemented a custom energy code for buildings based on the 2021 International Energy Conservation Code this year. The state joins 13 others that have adopted minimum energy codes based on the IECC 2021 or its equivalent, as well as the US Department of Energy, which has established similar requirements for new construction and retrofit owned buildings of the federal government.
The 2021 IECC increases insulation requirements, refines requirements for mechanical systems, and adds new provisions related to power and lighting, compared to the 2018 model code. An analysis by the Department of Energy found that buildings complying with the 2021 version would have an average energy saving of 9.38% of the site.
Illinois’ previous code was based on the 2018 IECC, but with amendments that made it less stringent, says Robert Coslow, administrator of professional services for the Illinois Capital Development Board (CDB). Its new code, which went into effect this year, is only 0.5 percent less stringent than the 2021 model code, and that’s only because the state chose to use the IECC’s insulation requirements of 2024, which were pushed back slightly from the 2021 model.
For the average new homeowner, the updated code means savings of nearly 10 percent on utility bills, CDB Executive Director TJ Edwards said in a statement.
“Illinois is committed to reducing energy consumption and greenhouse gas emissions,” Edwards said.
With this update, Illinois opted to have its code published by the International Code Council (ICC) for the first time. In the past, they used the IECC and then published state amendments.
“So if … you wanted to see what the Illinois code was, you had to take the model code and then you had to take our amendments and overlay them,” Coslow says. “It was a bit cumbersome.”
CDB made copies of the new Illinois energy code available to all municipalities in the state. Coslow says they wanted to make sure local officials were aware of the changes and that the newly released version is easier to use, enforce and reach users on the ground.
Illinois is also in the process of adopting a comprehensive energy code for communities looking to adopt more stringent requirements. Although still subject to public review, the proposed code is based on the IECC 2021 for residential buildings and the 2024 model for commercial. It includes electrical readiness provisions, such as having the ability to convert gas-to-electric appliances and connect rooftop solar systems, and promoting the use of efficient heat pumps.
Coslow says the proposed extension code has gone through CDB review and is halfway through the codification legislative process. Expect it to be available to the public by the end of October.
ICC CEO Dominic Simms praised Illinois for using building codes to improve energy efficiency, saying in a statement that the state “has become a leader on the national stage because of its commitment with the conservation of energy”.
