Wilmington Climate Zone & Energy Code

Climate Zone: IECC Climate Zone 4A (mixed-humid). Wilmington has a Mid-Atlantic climate with hot, humid summers (91°F/74°F cooling design) and cold winters (14°F heating design). Both sensible cooling, latent moisture removal, and heating loads drive equipment sizing.

Energy Code & Manual J Requirement: Delaware Residential Energy Code (IECC 2018). ACCA Manual J required for residential HVAC permits across all Delaware jurisdictions. The Delaware Division of Professional Regulation and local building departments administer enforcement.

Local Electric Utility: Delmarva Power (Pepco Holdings)

Building Department: City of Wilmington Building Permits Division

Local Trade Association: ACCA Mid-Atlantic Chapter / ASHRAE Delaware Valley Chapter