The Illinois Stretch Energy Code allows municipalities and projects funded by the Capital Development Board to achieve greater energy efficiency levels than those prescribed by the base Illinois Energy Conservation Code, without needing to develop their own code text. In particular, the Illinois Stretch Code is based on a refined version of the 2024 IECC standards.

The Illinois Energy Transition Act, passed in September 2021, addresses energy efficiency issues and includes provisions to create stretch energy codes for adoption. CEJA has since been renamed to the Illinois Energy Transition Act (IETA).