Definition
SEER2 (Seasonal Energy Efficiency Ratio 2) is the U.S. Department of Energy rating for how much cooling an air conditioner or heat pump delivers per watt-hour of electricity over a typical cooling season. It replaced SEER in 2023 under a tougher test procedure. Higher numbers mean less electricity for the same cooling.
Also called: Seasonal Energy Efficiency Ratio 2, SEER
Why it matters to you.
Kentucky sits in the DOE's Southeast region, so a split air conditioner installed here must reach 14.3 SEER2 below 45,000 BTU/h (13.8 SEER2 at or above), and a split heat pump 14.3 SEER2. Central Kentucky's long, humid summers keep cooling running for months, and by rating arithmetic a 17 SEER2 system uses about 16% less electricity than a 14.3 SEER2 one for the same cooling (1 − 14.3/17).
Practical guidance.
Ask for the outdoor and indoor model numbers on every quote and look up that exact matched pair in the AHRI Directory, because the SEER2 rating belongs to the combination, not the outdoor unit alone. On a heat pump quote, weigh SEER2 together with HSPF2, since the same equipment also heats the house all winter.
How SEER2 options compare.
| SEER2 rating | Where it sits | Electricity vs. 14.3 SEER2 minimum (1 − 14.3/x) | Electricity vs. 13.8 SEER2 large-AC minimum (1 − 13.8/x) |
|---|---|---|---|
| 13.8 | Kentucky minimum, split ACs at 45,000 BTU/h and above | Below the 14.3 minimum | Baseline (0%) |
| 14.3 | Kentucky minimum, split ACs below 45,000 BTU/h and all split heat pumps | Baseline (0%) | About 3% less |
| 16 | Mid-efficiency tier | About 11% less | About 14% less |
| 17 | Higher-efficiency tier | About 16% less | About 19% less |
| 18+ | High-efficiency tier, often variable-speed | About 21% less at 18; more above 18 | About 23% less at 18; more above 18 |
What is the minimum SEER2 for a new AC in Kentucky?
Kentucky is in the DOE's Southeast region. A split-system air conditioner installed on or after January 1, 2023 must be rated at least 14.3 SEER2 if its certified cooling capacity is below 45,000 BTU/h, or 13.8 SEER2 at 45,000 BTU/h and above. Split heat pumps must reach 14.3 SEER2 nationwide. Federal EER2 minimums apply only in the Southwest, not in Kentucky.
How much less electricity does a higher SEER2 system use?
The rating arithmetic is 1 − (lower SEER2 ÷ higher SEER2) for the same cooling load. Against Kentucky's 14.3 SEER2 minimum, that is about 11% less at 16, about 16% less at 17 and about 21% less at 18. Against the 13.8 SEER2 minimum for larger split ACs, it is about 14% less at 16. These are ratios of ratings, not bill estimates.
Can an older, lower-rated air conditioner still be installed in Kentucky?
Not as a new split air conditioner. Kentucky's Southeast minimums apply by installation date, and federal rules say any outdoor unit model with a certified combination rated below a region's standard cannot be installed in that region. That is why a quote should show the AHRI listing for the matched system, confirming it meets 14.3 or 13.8 SEER2 for its size.
Is SEER2 the same as the old SEER number?
No. SEER2 uses the DOE's M1 test procedure, which assumes higher external static pressure to better reflect real ductwork, so the same equipment scores lower in SEER2 than it did in SEER. Older brochures quoting SEER cannot be compared directly with SEER2 figures. Compare SEER2 only with SEER2.
Does a higher SEER2 rating help with Kentucky humidity?
Not by itself. SEER2 measures electricity used per unit of cooling, not how much moisture the system removes. Humidity control depends more on correct sizing and on how long the system runs; high-SEER2 equipment is often variable-speed, and its long, low-speed runs tend to dehumidify well. Ask about sizing and staging, not just the rating.
About this definition
Written by the Feistritzer Heating & Air Conditioning team — family owned and operated in Danville since 1976, Kentucky HVAC license M02584. Definitions inform; a whole-system diagnosis in your home decides.