Island, Washington HVAC Climate Zone

Island is located in IECC Climate Zone 4C (Mixed - Marine). Get accurate Manual J load calculations with official design temperatures for Island.

Climate Zone
4C
Winter Design
29°F
Summer Design
85°F
ZIP Codes
6

Island HVAC Contractors: Get Your Free Manual J Report

Climate Zone 4C requires precise load calculations. Upload your Island blueprint and get a professional Manual J report in 60 seconds— first report is FREE. Pre-loaded with Island's exact design temperatures (29°F winter / 85°F summer).

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Verify Your Island ZIP Code

Enter your ZIP code to confirm it's in Island and get climate zone details.

Island covers 6 ZIP codes: 98236, 98239, 98249, 98253, 98260, 98277

Island Design Temperatures

Official ASHRAE design temperatures for Island, used for accurate Manual J load calculations.

Winter 99% Design Temp
29°F
Summer 1% Design Temp
85°F
Summer Wet Bulb
67°F

IECC Requirements for Zone 4C

Minimum insulation and window requirements for Island per IECC 2021.

Wall Insulation:R-20
Roof/Ceiling:R-49
Floor Insulation:R-19
Window U-Factor:0.32
Window SHGC:0.4

Energy Code: 2021 IECC

Recommended HVAC Equipment for Island

Heating Systems

Gas furnace
Heat pump
Typical AFUE
92-95%

Cooling Systems

AC (optional)
Heat pump
Typical SEER
14 SEER

Get Free Manual J Calculations for Island

Upload your Island blueprint and get a professional Manual J load calculation using official Zone 4C design temperatures. First report is FREE.

Island design temps
Zone 4C compliant
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