IECC Climate Zone 1 — Very Hot-Humid

Updated Mar 26, 2026

Warmest US climate zone including Hawaii, south Florida, south Texas, Puerto Rico, and US Virgin Islands. Cooling-dominated. Code focus: window SHGC limits, cool roofs, duct sealing, and vapor retarder placement (exterior side).

TAGS

IECC hot-humid cooling Florida Hawaii

DETAILS

hdd range

<2,000

iecc zone

cooling focus

Primary

example cities

Miami, Honolulu, Key West, San Juan

roof insulation

R-30 to R-49

wall insulation

R-13 or R-20ci

RELATED KNOWLEDGE

📋 Code

IBC Section 1107 — Accessible Unit and Dwelling Unit Elements

Requires accessible common use elements within individual residential units.

📋 Code

IECC Section 603 — Energy Cost Budget Method

Provides performance-based alternative to prescriptive energy code requirements.

🌡️ Climate Zone

IECC Climate Zone 4A — Mixed-Humid (New York City, Philadelphia, Washington DC)

Mixed-humid climate with hot summers and cold winters. Heating degree days 3500-5500. Requires balanced envelope strategy: good insulation + solar heat gain management. Seismic Design Category B-C.

🌡️ Climate Zone

IECC Climate Zone 3B — Warm-Dry (Los Angeles, Las Vegas, Phoenix)

Warm-dry climate with mild winters and hot dry summers. Minimal heating needs. Primary concern is cooling load and solar heat gain. Seismic Design Category D-E in California. Wildfire risk zones.

📋 Code

NFPA 99 — Health Care Facilities Code

Comprehensive code for safety systems in hospitals and medical facilities.

🌿 certification

Fire Protection Engineer (FPE) Certification

Advanced certification for engineers specializing in fire safety systems.

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