Manual J calculator · TX
Manual J load calculation for Texas.
Reference data for Manual J load calculations in Texas: ASHRAE design temperatures for 5 top metros, energy code status, and TDLR licensing. The calculator does not load this page's data. It asks for your project location and looks up outdoor design conditions in its own dataset, by IECC 2021 climate zone for a ZIP code or by weather station for the 10 major metros in its city list.
Reference metro
Houston, TX (Harris County) · IECC 2015 zone 2A · winter 99% DB 34°F · summer 0.4% DB 97°F · MCWB 77°F.
0.4% DB: ASHRAE 2021 station value · Manual J 8 loads use the 1% DB
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01 · ASHRAE design conditions
Top 5 metros in Texas - ASHRAE design temperatures.
These are the ASHRAE 99% heating and 0.4% cooling design temperatures, not the absolute extremes. Outdoor temperatures go past the 0.4% cooling value about 35 hours per year and below the 99% heating value about 88 hours per year.
Manual J 8th edition load calculations use the 1% cooling and 99% heating design temperatures. For ENERGY STAR new homes, the EPA recommends "the ACCA Manual J, 8th edition, 1% cooling season design temperature and 99% heating season design temperature for the weather station that's geographically closest to the home" ( ENERGY STAR, Design Temperature Limits). For the same station the 1% cooling value is exceeded about 88 hours a year, against about 35 for the 0.4% value, so it is the lower of the two, and the table's cooling column is not the Manual J design temperature.
| Metro | County | Zone (IECC 2015) | Winter 99% DB | Summer 0.4% DB | MCWB |
|---|---|---|---|---|---|
| Houston | Harris County | 2A | 34°F | 97°F | 77°F |
| Dallas-Fort Worth | Dallas / Tarrant County | 3A | 27°F | 101°F | 75°F |
| San Antonio | Bexar County | 2A | 33°F | 99°F | 74°F |
| Austin | Travis County | 2A | 30°F | 100°F | 74°F |
| El Paso | El Paso County | 3B | 29°F | 101°F | 64°F |
Design temperatures are single station values from the ASHRAE 2021 Climatic Design Conditions (99% heating, 0.4% cooling), one airport station per metro, in whole °F within 1°F. DB = dry-bulb. MCWB = mean coincident wet-bulb at the 0.4% cooling design hour.
Zones in this table are from the IECC 2015 county map (PNNL county data). For a ZIP code, BuildSolver's calculator assigns zones by the IECC 2021 county map, where Dallas-Fort Worth is 2A (not 3A). A ZIP code near a zone line can get the neighboring zone.
02 · Energy code
Energy code baseline in Texas is IECC 2015.
In effect since 2016. Manual J load-calc documentation requirements flow from the state energy code; verify your specific AHJ's submittal rules before relying on the baseline.
- Texas SECO has not adopted IECC 2018 or 2021 statewide - IECC 2015 remains the baseline for residential construction outside home-rule jurisdictions.
- Home-rule cities (Austin, Dallas, Houston, San Antonio) may amend up to a newer IECC edition; verify with local AHJ before relying on this baseline.
Code status from SECO - State Energy Code adoption (Texas), verified December 15, 2024.
03 · Texas HVAC labor data
BLS wages and employment for HVAC mechanics in Texas.
These are state-level wages for occupation code 49-9021 - Heating, Air Conditioning, and Refrigeration Mechanics and Installers - from the most recent BLS Occupational Employment and Wage Statistics release.
- Median hourly wage
- $27.77
- Mean annual wage
- $59,130
- Employment estimate
- 34,730
Wage figures from BLS OEWS May 2025, SOC 49-9021 (state-level), released May 15, 2026.
04 · License & permit
HVAC licensing in Texas runs through TDLR.
State-level HVAC contractor licensing is administered by the Texas Department of Licensing and Regulation. Licenses renew annually, with 8 hours of continuing education per cycle.
License types
- Class A Air Conditioning & Refrigeration Contractor (unlimited tonnage)
- Class B Air Conditioning & Refrigeration Contractor (≤25 tons cooling, ≤1.5M BTU heating)
- Technician Registration
Permits
Most Texas AHJs require a mechanical permit for new HVAC installations, system replacements that change capacity, and ductwork modifications. Permits are issued by city building departments.
A replacement install typically requires a permit as well.
Texas has no single statewide permit portal - check the city or county building department for the specific job site.
05 · FAQ
Common Manual J questions for Texas contractors.
+Can I use BuildSolver for a Manual J in Texas without a TDLR license?
Yes - BuildSolver is a sizing aid for contractors and homeowners alike. Its output is a preliminary estimate for quotes and is not ACCA-approved for permit submission. Most Texas jurisdictions require a TDLR-licensed contractor to pull the permit; the load calc itself can be performed by anyone competent to apply ACCA Manual J.
+Which ASHRAE climate zones cover Texas?
Texas runs from zone 1A in the lower Rio Grande Valley (Cameron, Hidalgo, and Willacy counties on the IECC 2021 county map) to 4B on the Panhandle high plains, with 2A, 2B, 3A, and 3B in between. Some counties changed zones between IECC editions, so confirm your county's zone in the edition your AHJ enforces before applying default infiltration or window U-factor assumptions.
+Does Texas require IECC 2021 yet?
No. The State Energy Conservation Office (SECO) has kept IECC 2015 as the residential baseline. Home-rule cities such as Austin or Dallas may have adopted newer editions with local amendments - verify with the city's energy code amendment list before assuming the statewide baseline applies.
+What do HVAC technicians earn in Texas?
BLS OEWS May 2025 (released May 15, 2026) reports a median wage of $27.77/hr for HVAC mechanics and installers in Texas, with an annual mean of $59,130. The national median is $29.33/hr. TDLR-licensed Class A/B ACR contractors must complete 8 hours of continuing education each year, including 1 hour of Texas law and rules, per 16 TAC §75.25.
+How does Houston's design temp affect Manual J sizing?
Houston's ASHRAE 0.4% summer DB is 97°F with a 77°F mean coincident wet-bulb - high latent load. Sensible-only sizing typically under-equips dehumidification capacity by 15-20% in zone 2A. BuildSolver runs both sensible and latent at the ACCA Manual J 8th-edition split (§6 and §8) so the latent share shows in the output. Manual J 8th edition load calculations use the 1% cooling dry-bulb, which for the same station is at or below the 0.4% value.
+Can BuildSolver replace a permit-grade Manual J on a Texas permit?
No. BuildSolver is not ACCA-approved for permit submission. Use it for sales-phase sizing and client quotes, and produce the permit submittal in ACCA-approved software such as Wrightsoft Right-J8 or Cool Calc Manual J.
Try a Texas load calculation now.
The chat will ask follow-up questions like an experienced engineer - square footage, construction type, window count, insulation level - and run the Manual J on your inputs. Outdoor design conditions come from its own dataset (by IECC 2021 climate zone for a ZIP code, by weather station for the 10 major metros in its city list), not from the metro table on this page.
Start Texas calculationRelated · same climate zone
Other states with similar ASHRAE climate zones.
Climate-driven Manual J inputs such as infiltration, latent share, and design temperatures behave similarly across states that share a climate zone. Each page below gives that state's own design temperatures and licensing context. Zones combine the IECC 2015 and IECC 2021 county maps.
Data last reviewed October 16, 2026 · underlying sources as of May 15, 2026