West Virginia spans 2 IECC climate zones. Find your exact zone, design temperatures, and get free Manual J load calculations for any West Virginia location.
West Virginia spans 2 IECC climate zones (Zone 4A, Zone 5A), which means insulation requirements, design temperatures, and equipment specs vary significantly depending on location. The primary zone, Zone 4A (Mixed - Humid), is a mixed climate, with winter design temperatures as low as 13°F and summer highs reaching 91°F. HVAC contractors working across West Virginia need to verify the exact climate zone for each job site — using the wrong zone data leads to oversized or undersized equipment, failed inspections, and unhappy homeowners.
Minimum insulation R-values and window specifications required by the 2021 International Energy Conservation Code for West Virginia.
| Component | Zone 4A | Zone 5A |
|---|---|---|
| Ceiling / Attic | R-49 | R-49 |
| Walls | R-20 | R-20 |
| Floor | R-19 | R-30 |
| Window U-Factor | 0.32 | 0.3 |
| Window SHGC | 0.4 | 0.4 |
Source: IECC 2021 Table R402.1.2. Requirements shown are for residential construction. West Virginia contractors must use the zone that corresponds to the job site location.
These ASHRAE design temperatures determine how Manual J load calculations size heating and cooling equipment for West Virginia homes. The winter 99% value represents the coldest temperature expected, while the summer 1% value represents the hottest.
Mixed - Humid
Cool - Humid
Based on Climate Zone 4A (Mixed - Humid), here are typical HVAC equipment specifications for West Virginia installations.
Annual Fuel Utilization Efficiency for West Virginia furnaces
Seasonal Energy Efficiency Ratio for West Virginia AC systems
West Virginia's climate zone data ensures proper equipment sizing. No more callbacks from oversized or undersized systems.
West Virginia building departments require IECC-compliant Manual J calculations. Our tool uses official West Virginia climate data.
Right-sized systems based on West Virginia climate data reduce energy costs for homeowners and improve your reputation.
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