The lowest price is only half the cost
Comparing quotes by price is easy. But a heating and cooling system will run for fifteen years or more, and over that time what it costs to operate can outweigh what it cost to buy. The efficiency rating is how you compare that second cost.
The four ratings
| Rating | What it measures | Applies to | Minimum for new equipment in California |
|---|---|---|---|
| SEER2 | Cooling efficiency over a whole season | Air conditioners and heat pumps | 14.3 for most home-sized air conditioners and all split heat pumps |
| EER2 | Cooling efficiency at peak heat | Air conditioners | Required here; the level depends on system size and SEER2 |
| HSPF2 | Heating efficiency of a heat pump | Heat pumps | 7.5 |
| AFUE | Share of a furnace's fuel that becomes heat in your home | Gas furnaces | 80% today; 95% for furnaces made from December 2028 |
California sits in the federal "Southwest" region, which is why air conditioners here have to meet a hot-weather EER2 standard as well as a seasonal one.
Why the numbers have a "2"
Since January 2023, new equipment has been rated on SEER2, EER2 and HSPF2. The new test uses airflow conditions closer to those in real homes, so the same unit scores a little lower than it did under the old system: a 16 SEER air conditioner is roughly 15.2 SEER2. When you compare quotes, make sure every figure uses the same version.
Will higher efficiency pay you back?
The arithmetic is simple: the extra cost of the more efficient model, divided by what it saves you each year. What changes the answer is how hard your system works.
- Cooling. Inland, where air conditioners run long hours through summer, higher SEER2 and EER2 ratings tend to pay back faster. Near the coast, where cooling runs less, the case is weaker.
- Heating. Our mild winters mean furnaces and heat pumps run fewer hours than in colder states, so a top-efficiency heating rating usually takes longer to recover its cost.
- Comfort. Higher-efficiency systems are usually two-stage or variable-speed, which also makes them quieter and steadier. That has a value of its own.
- Incentives. Utility and state rebates can shorten the payback considerably, especially for heat pumps.
Ask for an estimate based on your own usage and rates, not a national average. After the payback point, the savings keep coming every year for the life of the system.
The rating belongs to the matched system
An air conditioner's or heat pump's rating applies to one specific combination of outdoor unit and indoor coil, tested together. Pair the outdoor unit with an old or different coil and the rating no longer applies. Ask your installer for the matched system's certificate from AHRI, the industry body that certifies these combinations.
Installation matters just as much. Refrigerant charge, airflow and duct leakage all affect real-world efficiency, which is why California requires many of them to be tested and verified after installation.
Savings beyond the equipment
- Seal and insulate leaky ducts, especially in a hot attic.
- Change or clean filters regularly; a clogged filter makes the whole system work harder.
- Use a programmable or smart thermostat to set back temperatures when you are asleep or away.
- Keep up seasonal maintenance; dirty coils and incorrect refrigerant levels quietly cut efficiency.
- Shade west-facing windows in summer, and use ceiling fans so you feel comfortable at a warmer setting.
Look for the ENERGY STAR label on the highest-efficiency models, and see energystar.gov for independent guidance.
Minimums per the U.S. Department of Energy 2023 standards; SEER to SEER2 conversion is approximate.