IECC Climate Zone Lookup by County
Find the IECC 2021 / 2024 climate zone for any US county, with the prescriptive envelope U-factors and window limits that zone requires.
- Climate zone and moisture regime for all 3,143 US counties
- Find the county from your current location
- Commercial and residential prescriptive U-factors, SHGC and window area limits
- IECC 2021 and 2024 editions
How to use
- Pick the state and county, or press Use my location.
- Read the climate zone (for example 5A: cool, humid) and the heating or cooling degree-day range that defines it.
- Switch between commercial and residential, and between the 2021 and 2024 IECC, to see the prescriptive maximum U-factors for roofs, walls and windows in that zone.
- The county you pick becomes the project location for the Envelope U-Factor and Sun Angle tools.
- Zones follow PNNL’s county guide for IECC 2021, which IECC 2024 keeps. Check for local amendments with the authority having jurisdiction.
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