Texas HVAC Load Calculation Guide
Texas is the largest HVAC market in the US by housing units, spanning four climate zones from humid Gulf Coast to arid West Texas — with a deregulated energy market and unique grid considerations.
Try the Texas HVAC Load Calculator
Get a preliminary estimate using Texas-specific design temperatures. Our heating load calculator uses ASHRAE methodology with the local climate inputs below.
Design Temperatures
| Parameter | Value | Source |
|---|---|---|
| Winter Design Temperature (99%) | 20°F | ASHRAE Handbook 2021 |
| Summer Design Temperature (1%) | 101°F | ASHRAE Handbook 2021 |
| IECC Climate Zone(s) | 2A (Hot - Humid), 2B (Hot - Dry), 3A (Warm - Humid), 3B (Warm - Dry) | ASHRAE 169-2021 |
| HVAC Load Type | Cooling-Dominated | — |
Texas Building Codes & Energy Requirements
| Requirement | Detail |
|---|---|
| Energy Code | 2015 IECC with Texas amendments |
| Minimum SEER | 14.0 SEER (federal minimum) |
| HVAC License Required | Yes — Texas Department of Licensing and Regulation (TDLR) — Air Conditioning and Refrigeration Contractor license required |
| Average Electricity Rate | $14.89/kWh (US average: $0.1701/kWh) |
Major Cities — Design Temperature Reference
| City | Summer Design (1% DB) | Winter Design (99% DB) | Load Type |
|---|---|---|---|
| Houston | 95°F | 20°F | Cooling |
| San Antonio | 98°F | 20°F | Cooling |
| Dallas | 100°F | 20°F | Cooling |
| Austin | 97°F | 20°F | Cooling |
| Fort Worth | 99°F | 20°F | Cooling |
| El Paso | 101°F | 20°F | Cooling |
Quick Facts
- State: Texas (TX)
- Climate Zone(s): 2A, 2B, 3A, 3B
- Winter Design: 20°F
- Summer Design: 101°F
- Energy Code: 2015 IECC with Texas amendments...
- Avg. Electric Rate: $14.89/kWh
- License Required: Yes
Texas HVAC Challenges
- Extreme summer heat across the state
- High humidity in eastern Texas (Houston area)
- Drought conditions affecting evaporative cooling viability
- Severe weather including hail and tornadoes
- ERCOT grid reliability concerns for HVAC planning
- Wide climate diversity from humid east to arid west
Local Utilities & Resources
- CenterPoint Energy (utility)
- Oncor Electric Delivery (utility)
- Texas-New Mexico Power (utility)
Texas HVAC FAQ
The ASHRAE winter design temperature for Texas is 20°F and the summer design temperature is 101°F. These values are used for heating and cooling load calculations per ACCA Manual J methodology.
Texas spans 2A, 2B, 3A, 3B per ASHRAE Standard 169-2021. This classification determines minimum insulation requirements, energy code compliance path, and HVAC equipment sizing parameters.
The required HVAC size depends on home square footage, insulation levels, window area, and orientation. For a typical 2,000 sq ft home in Texas, use our heating load calculator with the local design temperature of 20°F (winter) or 101°F (summer) for a preliminary estimate.
Texas Department of Licensing and Regulation (TDLR) — Air Conditioning and Refrigeration Contractor license required
Texas follows the 2015 IECC with Texas amendments. This code sets minimum requirements for HVAC equipment efficiency, duct insulation, envelope insulation, and ventilation.
Design Guides & Standards for Texas
Explore related resources for accurate HVAC sizing.