Hawaii County is in IECC Climate Zone 1A (Very Hot - Humid). Get accurate Manual J load calculations with official ASHRAE design temperatures for Hawaii County.
Hawaii County, Hawaii is classified under IECC Climate Zone 1A (Very Hot - Humid), a cooling-dominated region with humid moisture conditions. With 32 ZIP codes and 1 communities, every HVAC installation in Hawaii County must use the ASHRAE design temperatures of 31°F (99% winter heating) and 87°F (1% summer cooling) for accurate Manual J load calculations.
As a cooling-dominated zone, controlling solar heat gain is essential in Hawaii County. Windows must have an SHGC of 0.25 or lower, along with R-13 wall and R-30 ceiling insulation. Proper sizing prevents oversized AC systems that short-cycle and waste energy.
Minimum insulation R-values and window performance for Climate Zone 1A in Hawaii County, HI.
| Building Component | Minimum Requirement | Unit |
|---|---|---|
| Ceiling / Attic Insulation | R-30 | R-value |
| Wall Insulation | R-13 | R-value |
| Floor Insulation | R-13 | R-value |
| Window U-Factor | 0.4 | BTU/hr-ft²-°F |
| Window SHGC | 0.25 | Coefficient |
| Air Infiltration | 0.25 | ACH50 |
Climate Zone 1A requires precise load calculations. Upload your Hawaii County blueprint and get a professional Manual J report in 60 seconds— first report is FREE. Pre-loaded with Hawaii County's exact design temperatures (31°F winter / 87°F summer).
Enter your ZIP code to confirm it's in Hawaii County and get climate zone details.
Official ASHRAE design temperatures for Hawaii County, HI, used for accurate Manual J load calculations.
Minimum insulation and window requirements for Hawaii County per IECC 2021 energy code.
Climate Zone 1A: Very Hot - Humid - Cooling-dominated climate with extreme heat and high humidity year-round. Minimal heating requirements.
1 cities and communities in Hawaii County share Climate Zone 1A requirements.
Compare climate zones with other counties in Hawaii. Different zones require different HVAC equipment sizing.
Upload your Hawaii County blueprint and get a professional Manual J load calculation using official Zone 1A design temperatures. First report is FREE.
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