SEER2 (Seasonal Energy Efficiency Ratio 2) is the efficiency rating that replaced SEER for air conditioners and heat pumps starting January 1, 2023. If you’re shopping for new equipment, all new residential AC and heat pump units are rated in SEER2.
What the number means
SEER2 measures how efficiently a cooling system converts electricity into cooling over a typical season. Higher is more efficient. A 16 SEER2 unit uses less electricity to produce the same amount of cooling as a 14 SEER2 unit.
The “2” signals a new test method. The old SEER test ran at low external static pressure (0.1 in. w.c.), which was more favorable to equipment than real installations. SEER2 tests at 0.5 in. w.c. — closer to actual duct system resistance. Same equipment, more realistic number.
SEER vs. SEER2: how to compare
A SEER rating doesn’t directly equal a SEER2 rating. A 16 SEER unit roughly equals 15.2 SEER2, depending on the unit. You can use an approximate multiplier of 0.95 to convert, but for exact comparisons, use the manufacturer’s spec sheet.
If you’re comparing a unit you already own (SEER) to a new unit (SEER2), the new unit is likely more efficient than the numbers suggest at first glance.
2023 minimum requirements
The DOE set new minimums effective January 1, 2023:
- South and Southwest regions: 14.3 SEER2 (single-phase AC)
- North region: 13.4 SEER2 (single-phase AC)
- Heat pumps: 14.3 SEER2 (South), 13.4 SEER2 (North)
Equipment manufactured before 2023 can still be sold and installed until existing inventory runs out.
Both SEER2 and the older SEER rating come from the same underlying test standard, AHRI 210/240 — SEER2 uses the DOE’s updated 10 CFR Appendix M1 test procedure, not a different certifying body. Major manufacturers publishing SEER2 ratings on their spec sheets include Carrier, Trane, Lennox, Goodman, Rheem, and York.
What’s a good SEER2 rating?
| SEER2 rating | Tier | Notes |
|---|---|---|
| 14.3 | Minimum in most regions | Meets the 2023 standard, nothing more |
| 16–18 | Mid-tier efficiency | Meaningful improvement over minimum |
| 20+ | High efficiency | Best operating cost over time; highest purchase price |
| 25+ | Premium variable-speed | Full inverter-driven systems |
A higher SEER2 number costs more up front, and the payback period is entirely about how many cooling hours you actually run — Phoenix and Miami recoup a high-efficiency upgrade far faster than a mild-climate home that only runs AC a few weeks a year. Get the SEER2 rating in writing on any quote; a verbal “it’s a high-efficiency unit” isn’t the same as a spec-sheet number.
The right SEER2 depends on your climate and how much you run AC. In a hot climate where the AC runs 2,000+ hours per year, a higher SEER2 pays back faster. In a mild climate with light use, the payback period may be very long.
Thermostat’s role in efficiency
Your thermostat doesn’t change the unit’s SEER2 rating, but it directly affects actual operating efficiency:
- Smart setbacks (setting higher when away) reduce runtime significantly
- Fan mode: running the fan continuously (“On”) at low speed uses energy without adding cooling
- Optimal scheduling prevents the system from calling for cool after a setback by ramping up at the right time
—
FAQ
Is my existing AC rated in SEER or SEER2? If your AC was installed before 2023, it’s rated in SEER. The nameplate or manual will say “SEER XX.” Post-2023 equipment uses SEER2.
Can I compare SEER and SEER2 directly? Not directly. A 16 SEER unit is roughly equivalent to a 15.2 SEER2 unit. For rough comparison, multiply the SEER rating by 0.95.
Will a higher SEER2 lower my electric bill? Yes, relative to a lower-rated unit operating under the same conditions. The savings depend on how much you run your AC, your local electricity rate, and the climate.
Does SEER2 apply to heat pumps? Yes. Heat pumps have both a SEER2 rating (cooling efficiency) and an HSPF2 rating (heating efficiency). For heat pump heating performance specifically, see What Is HSPF2?.
