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
Washington and Oregon fall in the DOE's North region, where a new split air conditioner must reach 13.4 SEER2 and a split heat pump 14.3 SEER2. Cooling seasons in SW Washington are shorter than in the South, but by rating arithmetic a 17 SEER2 heat pump still uses about 16% less electricity than a 14.3 SEER2 one for the same cooling (1 − 14.3/17), which counts more as heat-wave days increase.
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 heating does most of the work here.
How SEER2 options compare
| SEER2 rating | Where it sits | Electricity vs. 13.4 SEER2 AC minimum (1 − 13.4/x) | Electricity vs. 14.3 SEER2 heat pump minimum (1 − 14.3/x) |
|---|---|---|---|
| 13.4 | Federal minimum, split air conditioners (WA/OR) | Baseline (0%) | Below the heat pump minimum |
| 14.3 | Federal minimum, split heat pumps (nationwide) | About 6% less | Baseline (0%) |
| 16 | Mid-efficiency tier | About 16% less | About 11% less |
| 17 | Higher-efficiency tier | About 21% less | About 16% less |
| 18+ | High-efficiency tier, often variable-speed | About 26% less at 18; more above 18 | About 21% less at 18; more above 18 |
What is the minimum SEER2 for a new AC in Washington or Oregon?
Washington and Oregon are outside the DOE's Southeast and Southwest regions, so the national (North) minimums apply. Since January 1, 2023, a new split-system air conditioner must be rated at least 13.4 SEER2 at any capacity, and a split-system heat pump at least 14.3 SEER2. Packaged units have their own minimums.
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 the 13.4 SEER2 air conditioner minimum, that is about 16% less at 16 and about 21% less at 17; against the 14.3 SEER2 heat pump minimum, about 11% less at 16 and about 16% less at 17. These are ratios of ratings, not bill estimates.
Does SEER2 matter much in the Pacific Northwest's short cooling season?
Less than in the South, because a SW Washington home runs its cooling for far fewer hours. It matters more if you choose a heat pump, which also needs to perform in winter, or if your home overheats during heat waves like the June 2021 event that broke Portland's all-time high on back-to-back days. For heat pumps, HSPF2 usually deserves equal or greater weight.
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.
Where do I find a system's real SEER2 rating?
Look up the exact outdoor and indoor model numbers together in the AHRI Directory of Certified Product Performance. The certified rating applies to that matched combination, so a high-rated outdoor unit paired with a mismatched coil or air handler may not deliver its headline number. Ask for the AHRI reference number on your quote.
About this definition
Written by the Home Energy Group team — a family-owned HVAC company celebrating 25 years of comfort & care across SW Washington and the Portland metro, licensed in Washington (WA LIC# HOMEEGI003J7) and Oregon (OR CCB# 184255). Definitions inform; an on-site diagnosis decides.
