McLennan County is in IECC Climate Zone 2A (Hot - Humid). Get accurate Manual J load calculations with official ASHRAE design temperatures for McLennan County.
McLennan County, Texas is classified under IECC Climate Zone 2A (Hot - Humid), a cooling-dominated region with humid moisture conditions. With 33 ZIP codes and 1 communities, every HVAC installation in McLennan County must use the ASHRAE design temperatures of 27°F (99% winter heating) and 100°F (1% summer cooling) for accurate Manual J load calculations.
As a cooling-dominated zone, controlling solar heat gain is essential in McLennan County. Windows must have an SHGC of 0.25 or lower, along with R-13 wall and R-30 ceiling insulation. Proper sizing prevents oversized AC systems that short-cycle and waste energy.
Minimum insulation R-values and window performance for Climate Zone 2A in McLennan County, TX.
| Building Component | Minimum Requirement | Unit |
|---|---|---|
| Ceiling / Attic Insulation | R-30 | R-value |
| Wall Insulation | R-13 | R-value |
| Floor Insulation | R-13 | R-value |
| Window U-Factor | 0.4 | BTU/hr-ft²-°F |
| Window SHGC | 0.25 | Coefficient |
| Air Infiltration | 0.25 | ACH50 |
Climate Zone 2A requires precise load calculations. Upload your McLennan County blueprint and get a professional Manual J report in 60 seconds— first report is FREE. Pre-loaded with McLennan County's exact design temperatures (27°F winter / 100°F summer).
Enter your ZIP code to confirm it's in McLennan County and get climate zone details.
Official ASHRAE design temperatures for McLennan County, TX, used for accurate Manual J load calculations.
Minimum insulation and window requirements for McLennan County per IECC 2021 energy code.
Climate Zone 2A: Hot - Humid - Cooling-dominated with hot, humid summers and mild winters. Significant cooling loads with moderate heating needs.
1 cities and communities in McLennan County share Climate Zone 2A requirements.
Compare climate zones with other counties in Texas. Different zones require different HVAC equipment sizing.
Upload your McLennan County blueprint and get a professional Manual J load calculation using official Zone 2A design temperatures. First report is FREE.
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