Naperville Climate Zone & Energy Code

Climate Zone: IECC Climate Zone 5A (cold-humid). Naperville shares Chicago's cold-humid climate — -4°F heating design and 91°F/74°F cooling design. Hot, humid summers with significant latent cooling loads and cold winters requiring robust heating make this a demanding four-season climate.

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

Local Electric Utility: ComEd (Commonwealth Edison / Exelon)

Building Department: City of Naperville Building Division

Local Trade Association: ACCA Illinois Chapter