Indiana is in IECC Climate Zone 5A (Cool - Humid). Get accurate Manual J load calculations with official design temperatures and IECC requirements.
Indiana falls entirely within IECC Climate Zone 5A (Cool - Humid), making it a heating-dominated state where furnace capacity and insulation R-values are the primary sizing concerns. With a winter 99% design temperature of 0°F and a summer 1% design temperature of 91°F, Indiana HVAC contractors must size systems for a 91°F temperature swing between extreme winter and summer conditions. Proper Manual J load calculations using these design temperatures are essential for code-compliant, right-sized installations that avoid callbacks and comfort complaints.
Minimum insulation R-values and window specifications required by the 2021 International Energy Conservation Code for Indiana.
| Component | Zone 5A |
|---|---|
| Ceiling / Attic | R-49 |
| Walls | R-20 |
| Floor | R-30 |
| Window U-Factor | 0.3 |
| Window SHGC | 0.4 |
Source: IECC 2021 Table R402.1.2. Requirements shown are for residential construction.
These ASHRAE design temperatures determine how Manual J load calculations size heating and cooling equipment for Indiana homes. The winter 99% value represents the coldest temperature expected, while the summer 1% value represents the hottest.
Cool - Humid
Based on Climate Zone 5A (Cool - Humid), here are typical HVAC equipment specifications for Indiana installations.
Annual Fuel Utilization Efficiency for Indiana furnaces
Seasonal Energy Efficiency Ratio for Indiana AC systems
Indiana's climate zone data ensures proper equipment sizing. No more callbacks from oversized or undersized systems.
Indiana building departments require IECC-compliant Manual J calculations. Our tool uses official Indiana climate data.
Right-sized systems based on Indiana climate data reduce energy costs for homeowners and improve your reputation.
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