Gilliam County is in IECC Climate Zone 5B (Cool - Dry). Get accurate Manual J load calculations with official ASHRAE design temperatures for Gilliam County.
Gilliam County, Oregon is classified under IECC Climate Zone 5B (Cool - Dry), a heating-dominated region with dry moisture conditions. With 3 ZIP codes and 1 communities, every HVAC installation in Gilliam County must use the ASHRAE design temperatures of 19°F (99% winter heating) and 93°F (1% summer cooling) for accurate Manual J load calculations.
As a heating-dominated zone, Gilliam County requires robust insulation — a minimum of R-20 in walls, R-49 in ceilings, and R-30 in floors. Windows must meet a U-factor of 0.3 or lower. These requirements ensure homes maintain comfort during the coldest 19°F design conditions.
Minimum insulation R-values and window performance for Climate Zone 5B in Gilliam County, OR.
| Building Component | Minimum Requirement | Unit |
|---|---|---|
| Ceiling / Attic Insulation | R-49 | R-value |
| Wall Insulation | R-20 | R-value |
| Floor Insulation | R-30 | R-value |
| Window U-Factor | 0.3 | BTU/hr-ft²-°F |
| Window SHGC | 0.4 | Coefficient |
| Air Infiltration | 0.15 | ACH50 |
Climate Zone 5B requires precise load calculations. Upload your Gilliam County blueprint and get a professional Manual J report in 60 seconds— first report is FREE. Pre-loaded with Gilliam County's exact design temperatures (19°F winter / 93°F summer).
Enter your ZIP code to confirm it's in Gilliam County and get climate zone details.
Official ASHRAE design temperatures for Gilliam County, OR, used for accurate Manual J load calculations.
Minimum insulation and window requirements for Gilliam County per IECC 2021 energy code.
Climate Zone 5B: Cool - Dry - Heating-dominated with cold, dry winters and warm summers. High heating loads in winter, moderate cooling needs.
1 cities and communities in Gilliam County share Climate Zone 5B requirements.
Compare climate zones with other counties in Oregon. Different zones require different HVAC equipment sizing.
Upload your Gilliam County blueprint and get a professional Manual J load calculation using official Zone 5B design temperatures. First report is FREE.
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