Boston Climate Zone & Energy Code

Climate Zone: IECC Climate Zone 5A (cold-humid). Boston's Atlantic coast location produces cold winters (9°F heating design), hot humid summers (91°F/72°F cooling design), and persistent maritime humidity that affects both cooling and building moisture management.

Energy Code & Manual J Requirement: Massachusetts Building Code (IECC 2021 Base Code, with Stretch Code available for municipalities). ACCA Manual J required for residential HVAC permits. Massachusetts has among the most progressive energy codes in the US, with the Stretch Code adding requirements beyond base IECC.

Local Electric Utility: Eversource Energy (formerly NSTAR)

Building Department: City of Boston Inspectional Services Department (ISD)

Local Trade Association: ACCA New England / ASHRAE New England Chapter / SMACNA New England