Joliet Climate Zone & Energy Code

Climate Zone: IECC Climate Zone 5A (cold-humid). Joliet and Will County share the Chicago area's cold-humid climate — -4°F heating design and 91°F/74°F cooling design. Hot, humid summers and cold winters with Great Lakes weather variability characterize this market.

Energy Code & Manual J Requirement: Illinois IECC 2024. ACCA Manual J required for residential HVAC permits in Will County and Joliet jurisdictions.

Local Electric Utility: ComEd (Commonwealth Edison / Exelon)

Building Department: City of Joliet Building Department

Local Trade Association: ACCA Illinois Chapter