Illinois is the latest jurisdiction to release a stretch energy code that provides standards for communities to mandate more efficient building construction. St. Louis, Mo., and a few states, including California, Colorado, and Massachusetts, currently have stretch codes in place.
Illinois' new Stretch Energy Code can be adopted by municipalities on June 30. For residential buildings of all sizes, the code provides tiered benchmarks for energy efficiency levels based on a site energy index relative to the 2006 International Energy Conservation Code (IECC).
For instance, by the end of 2025, sector-specific buildings must achieve a site energy index no greater than 40% of the 2006 IECC.
Efficiency requirements in the 2006 IECC are far lower than the 2021 version. Policymakers opted for the less stringent code, figuring that more communities would adopt a stretch code if it was easier to meet than the current IECC.