What is SEER2, and how is it different from SEER?
SEER2 is the seasonal cooling efficiency rating the Department of Energy has required since January 1, 2023. It measures the same thing as SEER but under a new test that adds more duct resistance, so a unit's SEER2 number reads lower than its old SEER number. Compare SEER2 only with SEER2. Minnesota's minimum for split central AC is 13.4 SEER2.
Key points
- SEER2 and SEER both measure cooling delivered per unit of electricity over a season. SEER2 uses DOE's newer test, in effect since January 1, 2023.
- The new test raises external static pressure by up to five times, per AHRI, so SEER2 numbers come out lower for the same unit. There is no official conversion factor.
- Minnesota is in DOE's North region: 13.4 SEER2 minimum for split central AC, 14.3 SEER2 and 7.5 HSPF2 for split heat pumps.
- EER2 is the hot-afternoon efficiency at 95°F. It carries weight in the desert Southwest, much less here.
- A short cooling season means high SEER2 pays back slowly in Minnesota. Buy staging for comfort, and size it with a Manual J.
SEER2 is the seasonal cooling efficiency rating on every central air conditioner and heat pump made since January 1, 2023. It measures the same thing SEER did, but the Department of Energy changed the test to add more duct resistance, so the same unit gets a lower number under SEER2 than it did under SEER, and the two can't be compared directly.
That's the whole reason a quote today might say 15.2 where an older brochure said 16. The equipment didn't get worse. The test got more realistic.
What do SEER and SEER2 measure?
DOE defines the seasonal energy efficiency ratio as the total heat an air conditioner removes from your house over a cooling season, divided by the electricity it uses over that season. Higher is better: a higher rating means fewer kilowatt-hours for the same cooling. SEER2 is that same ratio, measured under DOE's newer test procedure (Appendix M1). The companion ratings changed the same way:
| Rating | What it tells you | Old name |
|---|---|---|
| SEER2 | Cooling efficiency averaged over a season | SEER |
| EER2 | Cooling efficiency on a hot afternoon at 95°F | EER |
| HSPF2 | Heat pump heating efficiency averaged over a season | HSPF |
DOE says it created the new metrics because the test procedure changed, and the new procedure is meant to better reflect real-world installation and use.
Why does a SEER2 rating read lower than SEER?
The old test ran equipment against very little airflow resistance, much less than a real duct system with a filter, a coil and a few turns of ductwork puts on the blower. AHRI, the industry group that certifies these ratings, says the Appendix M1 test increases the external static pressure used in testing by up to five times. ENERGY STAR's specification lists conventional ducted systems as tested at a minimum of 0.50 inches of water column.
More resistance means the blower works harder and the system moves a little less heat per watt, so the number drops. AHRI says the new metrics have lower numerical values than the old ones, and that the 2023 minimums rose only about 1 SEER from pre-2023 levels once the test change is accounted for.
There is no official conversion factor. DOE's own guidance says the new ratings are similar to the old ones but not directly comparable, and that compliance is judged only on the measured SEER2, EER2 or HSPF2. You'll find rules of thumb online; don't use them to compare two quotes. Compare SEER2 to SEER2, for the exact matched system.
Minnesota's minimums
DOE splits the country into regions for central air conditioners. States with 5,000 or more heating degree days are in the North region, and Minnesota is one of them. Here are the minimums from DOE's 2023 standards guidance:
| Equipment | Minimum in the North region |
|---|---|
| Split-system central AC | 13.4 SEER2 (no EER2 requirement) |
| Split-system heat pump | 14.3 SEER2 and 7.5 HSPF2 (national) |
| Single-package AC | 13.4 SEER2 |
| Single-package heat pump | 13.4 SEER2 and 6.7 HSPF2 (national) |
In the North, the rule follows the date the unit was manufactured, not the date it's installed. DOE says units manufactured before January 1, 2023 to the older standard may still be installed here. The Southeast and Southwest have higher minimums and an install-date rule, and the Southwest adds an EER2 requirement because hot, dry afternoons are where EER matters most.
ENERGY STAR is the other marker you'll see. Its earlier bar for split central AC was 15.2 SEER2 and 12.0 EER2, but ENERGY STAR ended the central air conditioner portion of its specification on February 2, 2026. Heat pumps are still certified, at 15.2 SEER2, 11.0 EER2 and 7.8 HSPF2 for split systems.
Why does a high-SEER2 AC pay back slowly in Minnesota?
Cooling electricity scales roughly with 1 divided by the rating. Going from 13.4 SEER2 to 16 SEER2 cuts cooling electricity by about 16%. Going to 20 SEER2 cuts it by about a third. Those are real percentages, but they apply to your cooling kilowatt-hours, and a Minnesota cooling season is short. Pull a year of electric bills, estimate how much of July and August is air conditioning, and apply the percentage. That's your yearly savings. Our post on high-efficiency AC cost versus savings walks through the math.
What you feel every day is humidity. Our summer design condition is about 88°F with a lot of moisture in the air (Minnesota's energy code tables list 88°F dry bulb and 72°F wet bulb for Minneapolis and Saint Paul). A single-stage unit sized for the hottest afternoon hits the setpoint quickly and shuts off before it pulls much water out. Two-stage and variable-speed units run longer on low and leave the house drier, and they usually carry higher SEER2 ratings too. Our two-stage vs variable-speed guide covers how each one feels.
How do you make sure you get the SEER2 rating you paid for?
A SEER2 rating belongs to a certified combination: the outdoor unit, the indoor coil and the furnace or air handler. Ask for the AHRI certificate for your exact match, or look it up in the AHRI directory. A high-rated condenser on a mismatched coil doesn't earn its number.
Then the install decides the rest. The new test assumes real duct resistance, and many older Twin Cities houses have more than that: one small return for a whole floor, crushed flex duct, or a thick filter crammed into a slot sized for a thin one. Airflow that's too low costs efficiency and comfort. Our posts on duct sealing and AC sizing cover the fixes, and every replacement we do is sized with a Manual J load calculation, not the old nameplate.
What you can check yourself
- Your current unit's rating. The data plate or yellow EnergyGuide label may list SEER (pre-2023) or SEER2. Don't compare an old SEER with a new SEER2 as if they were the same scale.
- Every quote. Each should list SEER2 for the matched system, the outdoor and indoor model numbers, and the staging (single, two-stage or variable).
- Rebates. Xcel Energy's Minnesota cooling rebates are tied to quality-installation requirements, and some need a participating contractor, so ask before you count on one.
Cost and next steps
Central AC replacement with us runs $5,200–$9,800 installed; staging, tonnage and the matched coil move the price more than a point of SEER2 does. If a heat pump is on your list, it cools the same way and adds spring and fall heating; our heat pump page explains the ratings that matter in winter. For local pricing context, see our Minneapolis AC installation page or Saint Paul AC installation page.
For a written quote that lists single-stage, two-stage and variable-speed options side by side with SEER2 for each matched system, start from our AC installation page or call 612-429-3465. We're open 7 days, 7am–9pm.
Questions
Is 16 SEER2 the same as 16 SEER?
No. A unit rated 16 SEER2 would have tested higher on the old SEER procedure, because the new test adds more airflow resistance. DOE says the new and old ratings are similar but not directly comparable, and it doesn't publish a conversion factor. When you compare quotes, make sure every number on the page is SEER2, and look up the exact outdoor unit, coil and furnace combination.
What is the minimum SEER2 in Minnesota?
Minnesota is in DOE's North region, where a split-system central air conditioner must be at least 13.4 SEER2, with no separate EER2 requirement. Split-system heat pumps must be at least 14.3 SEER2 and 7.5 HSPF2 nationwide. In the North, the rule is based on when the unit was manufactured, so equipment built before 2023 to the older standard could still be installed.
Can I still buy an ENERGY STAR central air conditioner?
ENERGY STAR ended the central air conditioner portion of its specification on February 2, 2026; heat pumps are still certified. Its earlier bar for split central AC was 15.2 SEER2 and 12.0 EER2, which is still a reasonable marker for a mid-efficiency unit. For utility rebates, check the program's own current requirements rather than the label.
What SEER2 should I buy for a Minnesota house?
For most homes, the staging matters more than the number. A two-stage or variable-speed unit runs longer on low, which pulls more humidity out of a muggy July house, and those units tend to carry higher SEER2 ratings anyway. A top-of-the-line rating alone pays back slowly on our short cooling season, so run the math on your own electric bills.
Sources
- AHRI directory ahridirectory.org
- ENERGY STAR energystar.gov
- U.S. Department of Energy energy.gov