El Cajon Climate Zone & Energy Code

Climate Zone: CEC Climate Zone 10 (east San Diego County inland valley). IECC Climate Zone 3B. El Cajon's inland valley position produces hot summers — 96°F cooling design — unlike coastal San Diego (79°F). Winter remains mild (32°F heating design), reflecting San Diego County's generally benign winter climate.

Energy Code & Manual J Requirement: California Title 24 Part 6 (2025 edition, effective January 1, 2026). ACCA Manual J required for residential HVAC sizing. All El Cajon and San Diego County jurisdictions enforce Title 24.

Local Electric Utility: San Diego Gas & Electric (SDG&E)

Building Department: City of El Cajon Building Division

Local Trade Association: ACCA California / ASHRAE San Diego Chapter