Last updated: October 27, 2026. Prices, delivery rates and efficiency rules checked October 27, 2026. EIA’s 2026 monthly figures are preliminary.
Air conditioning is why a Texas power bill swells between spring and August. Its cost comes down to three numbers: the unit’s size, its efficiency, and how many hours it runs. You’ll find the first two on the outdoor unit’s label. The third depends on the weather and on you.
My family and I moved to Fort Bend County, in CenterPoint’s territory, in 2025, so CenterPoint’s delivery rates are the ones that apply to my own home. Below is the math, using today’s prices and efficiency figures from DOE and ENERGY STAR.
Quick answer
- A 3-ton central AC at the Southern minimum efficiency (14.3 SEER2) draws about 2.52 kW while running. That’s about 40¢ an hour at the Texas average of 15.91¢/kWh (August 2026, preliminary, EIA).
- Run it 12 hours a day and you pay about $4.81 a day, or $144.19 a month.
- In CenterPoint’s area, each kWh carries 6.5333¢ of delivery plus your plan’s energy charge: about 31¢ an hour with an example 5.93¢ energy charge.
- Federal minimum for new split ACs in Texas: 14.3 SEER2 under 45,000 Btu/h (3.75 tons), 13.8 SEER2 at or above (10 CFR 430.32).
- DOE on thermostats: “You can save as much as 10% a year on heating and cooling by simply turning your thermostat back 7°-10°F for 8 hours a day from its normal setting.” (DOE)
The formula: tons, SEER2 and kilowatts
AC capacity is sold in “tons.” One nominal ton is 12,000 Btu per hour (DOE Building America), so a 3-ton unit removes 36,000 Btu an hour.
SEER2 is the efficiency rating. ENERGY STAR defines it as the total heat removed during the cooling season, in Btu, divided by the total electricity used in the same season, in watt-hours (ENERGY STAR). So Btu per hour divided by SEER2 gives watts:
kW while running ≈ (tons × 12,000) ÷ SEER2 ÷ 1,000
Multiply by hours of runtime to get kWh, then by your price to get dollars. Keep in mind it’s a seasonal average. On a 100°F afternoon the unit draws more, and on a mild evening it draws less.
| Size | 13.4 SEER2 | 14.3 SEER2 | 15.2 SEER2 | 17 SEER2 | 20 SEER2 |
|---|---|---|---|---|---|
| 2 tons (24,000 Btu/h) | 1.79 kW | 1.68 kW | 1.58 kW | 1.41 kW | 1.20 kW |
| 2.5 tons (30,000 Btu/h) | 2.24 kW | 2.10 kW | 1.97 kW | 1.76 kW | 1.50 kW |
| 3 tons (36,000 Btu/h) | 2.69 kW | 2.52 kW | 2.37 kW | 2.12 kW | 1.80 kW |
| 3.5 tons (42,000 Btu/h) | 3.13 kW | 2.94 kW | 2.76 kW | 2.47 kW | 2.10 kW |
| 4 tons (48,000 Btu/h) | 3.58 kW | 3.36 kW | 3.16 kW | 2.82 kW | 2.40 kW |
| 5 tons (60,000 Btu/h) | 4.48 kW | 4.20 kW | 3.95 kW | 3.53 kW | 3.00 kW |
Twice the size means twice the power for every hour it runs. Efficiency matters less than size, but it still counts: going from 14.3 to 20 SEER2 cuts the draw by more than a quarter.
If your unit is older, its label may show SEER, not SEER2. The two come from different federal test procedures (appendix M and M1) (ENERGY STAR), so compare SEER2 with SEER2.
How many hours does a Texas AC actually run?
Runtime depends on your house. Still, two public numbers give a realistic range.
- The annual total. Texas homes that use air conditioning used an average of 3,979 kWh a year for it in EIA’s latest Residential Energy Consumption Survey (2020), plus 708 kWh for the indoor blower in cooling mode (RECS table CE5.3.ST). For a 3-ton, 14.3 SEER2 unit, 3,979 kWh works out to about 1,581 hours at full output over a year (GridPenny calculation).
- The summer jump. The average Texas home used about 1,670 kWh in August 2026 against 821 kWh in March 2026 (EIA, preliminary). Pin the whole increase on cooling (848 kWh using EIA’s unrounded figures) and you get roughly 27 kWh a day, or about 11 hours a day of full-output running for a 3-ton, 14.3 SEER2 unit. That’s rough, since other summer loads count too.
AC is close to universal here: 95% of Texas homes used air conditioning in 2020, and 83% had central AC (EIA RECS). I’d plan on 8 to 12 hours of compressor time a day in a normal Texas summer, and more in a heat wave. Treat those as examples, not measurements.
What it costs per hour, day and month
Two prices matter here. The first is EIA’s Texas average residential price, 15.91¢/kWh in August 2026 (preliminary; released October 23, 2026). It’s an all-in average with delivery included.
The second is what an extra kWh costs in CenterPoint’s area. CenterPoint charges $2.11 a month plus $2.79 for metering and 6.5333¢ per kWh, effective October 1, 2026 (rates report, matching the PUCT TDU page). The $4.90 doesn’t move with AC use. The 6.5333¢ lands on every kWh.
For the energy part, I’ve used 5.93¢/kWh as an example. That’s the charge that would produce the median price of today’s 12-month plain fixed-rate CenterPoint plans (12.95¢ at 1,000 kWh, 34 plans on Power to Choose) with no base charge. Add delivery and each AC kWh costs about 12.46¢. Your own energy charge is on your EFL.
| Unit (at Texas minimum) | kW | Per hour (EIA avg.) | Per month (EIA avg.) | Per hour (CenterPoint example) | Per month (CenterPoint example) |
|---|---|---|---|---|---|
| 2 tons, 14.3 SEER2 | 1.68 | 27¢ | $96.13 | 21¢ | $75.28 |
| 2.5 tons, 14.3 SEER2 | 2.10 | 33¢ | $120.16 | 26¢ | $94.10 |
| 3 tons, 14.3 SEER2 | 2.52 | 40¢ | $144.19 | 31¢ | $112.92 |
| 3.5 tons, 14.3 SEER2 | 2.94 | 47¢ | $168.22 | 37¢ | $131.74 |
| 4 tons, 13.8 SEER2 | 3.48 | 55¢ | $199.22 | 43¢ | $156.02 |
| 5 tons, 13.8 SEER2 | 4.35 | 69¢ | $249.03 | 54¢ | $195.03 |
Runtime matters as much as size. Here’s the same 3-ton unit across a range of summer days:
| Runtime per day | kWh per day | Per day (EIA avg.) | Per 30 days (EIA avg.) | Per 30 days (CenterPoint example) |
|---|---|---|---|---|
| 6 hours | 15.1 | $2.40 | $72.10 | $56.46 |
| 8 hours | 20.1 | $3.20 | $96.13 | $75.28 |
| 12 hours | 30.2 | $4.81 | $144.19 | $112.92 |
| 16 hours | 40.3 | $6.41 | $192.26 | $150.57 |
A typical summer month for one 3-ton system runs roughly $96.13 to $144.19 at the state average price, which lines up with the spring-to-August jump in the average Texas electric bill. In Houston, a big slice of each AC kWh is CenterPoint’s delivery charge, which no plan can shop away.
Thermostat settings: what DOE actually says
DOE’s exact words, from its home upgrades guide: “You can save as much as 10% a year on heating and cooling by simply turning your thermostat back 7°-10°F for 8 hours a day from its normal setting.”
Read it closely. It says “as much as,” it covers heating and cooling together, and it assumes a 7 to 10 degree setback for eight hours. In summer that means letting the house warm up while you’re out or asleep.
As an upper bound, 10% of the Texas average of 3,979 kWh of AC use is about 398 kWh a year, or roughly $63.31 at 15.91¢.
The same DOE page notes that programmable thermostats “have generally not been recommended for heat pump systems,” though some newer models are designed for them. ENERGY STAR adds that homes with high heating and cooling bills, or that sit empty much of the day, “can save approximately $100 a year” with an ENERGY STAR certified smart thermostat (ENERGY STAR).
The federal minimum SEER2 in Texas
DOE sets national efficiency standards, with stricter levels in the Southeast, which includes Texas. For units installed on or after January 1, 2023, the rule reads (10 CFR 430.32(c), eCFR, up to date as of October 23, 2026):
| Equipment | Minimum in Texas | Notes |
|---|---|---|
| Split-system central AC, under 45,000 Btu/h (under 3.75 tons) | 14.3 SEER2 | Southeast regional standard |
| Split-system central AC, 45,000 Btu/h and up | 13.8 SEER2 | Southeast regional standard |
| Single-package central AC | 13.4 SEER2 | National standard; no extra Southeast SEER2 level |
| Split-system heat pump | 14.3 SEER2 (7.5 HSPF2) | National standard |
ENERGY STAR used to be the shortcut for “better than minimum.” Not anymore. EPA sunset the ENERGY STAR specification for central air conditioners on February 1, 2026 (ENERGY STAR). Heat pumps are still covered: a certified split-system heat pump needs at least 15.2 SEER2, 11.0 EER2 and 7.8 HSPF2 (ENERGY STAR). If you’re replacing a central AC, look at the SEER2 number itself rather than for the label.
When replacing your AC pays off
ENERGY STAR says it may be time to call a contractor if your heat pump or air conditioner is more than 10 years old, if it needs frequent repairs while bills climb, or if some rooms stay too hot (ENERGY STAR). It also warns that improper installation “can reduce system efficiency by up to 30 percent,” and to fix big air leaks and ducts first (ENERGY STAR).
My view is that a high-efficiency unit pays off best when the old one is dying anyway. Then you only pay the price difference between a minimum unit and a better one. Energy use falls in proportion to the SEER2 ratio, so going from 14.3 to 17 SEER2 cuts AC kWh by about 16%:
| Yearly AC use now | SEER2 change | kWh saved per year | Saved at EIA avg. | Saved at CenterPoint example |
|---|---|---|---|---|
| 3,000 kWh | 14.3 → 17 | 476 kWh | $75.81 | $59.37 |
| 3,979 kWh | 14.3 → 17 | 632 kWh | $100.54 | $78.74 |
| 6,000 kWh | 14.3 → 17 | 953 kWh | $151.61 | $118.74 |
For a payback period, divide the extra cost of the efficient unit, from real quotes, by the yearly savings. If that takes more than 10 years, call it a comfort purchase, not a money-saver. I don’t list equipment prices here because they depend so much on the house and the contractor.
DOE goes further: “Switching to high-efficiency air conditioners and taking other actions to keep your home cool could reduce energy use for air conditioning by up to 50%” (DOE).
Maintenance that keeps the cost down
| Task | How often | Why it matters (ENERGY STAR) |
|---|---|---|
| Check the air filter | Every month in summer; change at least every 3 months | A dirty filter slows airflow and makes the system work harder |
| Professional tune-up | Yearly; book the cooling check in spring | Improves efficiency and comfort, and contractors get busy once summer starts |
| Clean coils, check refrigerant charge | At the tune-up | Dirty coils and a wrong charge both lower efficiency |
| Clean and adjust blower parts | At the tune-up | Airflow problems can cut efficiency by up to 15% |
| Seal and insulate ducts in the attic or garage | Once, then check | Can improve efficiency by as much as 20% |
You can check the filter today. For ducts, ENERGY STAR says to start with the ones in the attic, crawlspace or garage.
FAQ
What SEER2 rating do I need in Texas?
For a new split-system central AC, at least 14.3 SEER2 under 45,000 Btu/h and 13.8 SEER2 at or above it. A lower-rated combination can’t be installed in Texas.
How much can a thermostat setback save?
DOE says as much as 10% a year on heating and cooling, with a 7 to 10°F setback for eight hours a day.
Does a free-nights plan help with AC costs?
Only if a big share of your use falls in the free hours, and the hottest part of the day usually isn’t one of them. Check your own split first. Our look at free nights and weekends plans in Texas shows how to do the break-even math.
If summer bills have you shopping for a new plan, start with our Power to Choose guide and learn how to read an Electricity Facts Label before you sign. Curious how Texas prices stack up nationally? See electricity prices by state. Just moved? Here’s how to set up electricity in a new Texas home.
Sources
- U.S. EIA, Electric Power Monthly, Table 5.6.A (data for August 2026, released Oct 23, 2026; preliminary) and retail sales data (Texas residential sales and customers by month). Checked Oct 27, 2026.
- U.S. EIA, 2020 Residential Energy Consumption Survey, state data: Table CE5.3.ST and Highlights for air conditioning by state. Checked Oct 27, 2026.
- CenterPoint Energy Houston Electric Rates Report, 10/1/2026 and the PUCT TDU delivery charges page. Checked Oct 27, 2026.
- Power to Choose offer export, downloaded Oct 27, 2026: English-language CenterPoint listings, 12-month plain fixed-rate plans.
- U.S. DOE: 10 CFR 430.32, energy conservation standards (eCFR, up to date as of Oct 23, 2026); Home Upgrades; Building America Strategy Guideline: Accurate Heating and Cooling Load Calculations. Checked Oct 27, 2026.
- ENERGY STAR: Heat Pump Equipment Key Product Criteria, Central Air Conditioners Sunset, Heat & Cool Efficiently, Maintenance Checklist and When is it time to replace?. Checked Oct 27, 2026.