SEER2 is the number on the EnergyGuide label and the line on every replacement quote that customers ask about. It is a federal rating with a federal test behind it, and the minimum you're allowed to install depends on where the job is. Here's what it measures, what changed in 2023 and what the current numbers are.
SEER2 in plain English
SEER2 is miles per gallon for air conditioning. It tells you how many BTUs of heat the system removes from the house for each watt-hour of electricity it uses, averaged over a typical cooling season. ENERGY STAR's specification defines it as the total heat removed during the annual cooling season, in BTU, divided by the total electrical energy consumed in the same season, in watt-hours1.
A 16 SEER2 system uses less electricity than a 14 SEER2 system to deliver the same cooling. It doesn't cool the house any faster; that's capacity, measured in tons.
Formula
Why did SEER become SEER2?
DOE's energy conservation standards switched from SEER and HSPF to SEER2 and HSPF2 for central air conditioners and heat pumps manufactured on or after January 1, 20232. The ratings come from a new test, Appendix M1, which now incorporates AHRI 210/240-20243.
The biggest change for ducted equipment is the air side. New York State's Clean Heat program summarizes the shift4:
| SEER (Appendix M) | SEER2 (Appendix M1) | |
|---|---|---|
| Applies to | Manufactured before Jan. 1, 2023 | Manufactured on or after Jan. 1, 2023 |
| External static pressure in the test | 0.1 to 0.2 in. w.c. | 0.5 in. w.c. |
| Default fan power, coil-only units | 365 W per 1,000 CFM | 441 W per 1,000 CFM |
| Peak metric | EER | EER2 |
| Typical result for the same equipment | Higher number | Lower number |
Source: NYS Clean Heat, Efficiency Ratings Explained: DOE Appendix M1
The 0.5 in. w.c. test condition is closer to real ductwork (see static pressure), so ratings drop. NYS Clean Heat notes the lower values don't mean the equipment got less efficient, and that there's no single correlation: ducted systems are affected more than ductless ones because they're more sensitive to static pressure4.
What are the SEER2 minimums?
Federal minimums for products manufactured on or after January 1, 2023, from 10 CFR 430.32(c)(5) and (c)(6)2:
| Product class | North | Southeast | Southwest |
|---|---|---|---|
| Split AC, under 45,000 BTU/h | 13.4 SEER2 | 14.3 SEER2 | 14.3 SEER2, plus EER2 11.7 (or 9.8 if SEER2 is 15.2 or higher) |
| Split AC, 45,000 BTU/h and up | 13.4 SEER2 | 13.8 SEER2 | 13.8 SEER2, plus EER2 11.2 (or 9.8 if SEER2 is 15.2 or higher) |
| Split heat pump | 14.3 SEER2, 7.5 HSPF2 | Same | Same |
| Single-package AC | 13.4 SEER2 | 13.4 SEER2 | 13.4 SEER2, plus EER2 10.6 |
| Single-package heat pump | 13.4 SEER2, 6.7 HSPF2 | Same | Same |
Southeast is Alabama, Arkansas, Delaware, Florida, Georgia, Hawaii, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, Puerto Rico, South Carolina, Tennessee, Texas, Virginia, the District of Columbia and the U.S. territories. Southwest is Arizona, California, Nevada and New Mexico. Everything else is North2.
What is a good SEER2 rating?
ENERGY STAR's Version 6.2 specification for central air conditioners and heat pumps (revised March 2025) sets these levels1:
ENERGY STAR also requires that the SEER2 and HSPF2 used for certification be identical to what was reported to DOE and shown on the FTC EnergyGuide label1. Utility rebates often set their own higher bars, so check the program's current list.
How much does higher SEER2 save?
The math is simple; the inputs are local. Seasonal electricity use is the season's cooling divided by SEER2.
Seasonal cooling energy
Worked example (example inputs)
A 3-ton system (36,000 BTU/h) running the equivalent of 1,500 full-load hours a season, with electricity at $0.17 per kWh. All three inputs are examples; use local figures.
| SEER2 | Seasonal kWh | Seasonal cost |
|---|---|---|
| 13.4 | 36,000 × 1,500 ÷ 13.4 ÷ 1,000 ≈ 4,030 | about $685 |
| 16.0 | 36,000 × 1,500 ÷ 16.0 ÷ 1,000 = 3,375 | about $574 |
| Difference | about 655 kWh | about $111 a year |
Show it to customers as an estimate. Real savings depend on the house, the ductwork and how the system is installed and charged.
SEER2 vs EER2 vs HSPF2
- SEER2: seasonal cooling efficiency.
- EER2: cooling efficiency at a single 95°F outdoor condition2. The Southwest has EER2 minimums because peak heat matters there.
- HSPF2: seasonal heating efficiency for heat pumps. See HSPF2.
DOE has already adopted a further test, Appendix M2, built on new metrics called SCORE and SHORE. It applies once DOE sets amended standards based on those metrics; until then, Appendix M1 and SEER2 remain the basis for compliance3.
How SEER2 shows up in TradesWork
In TradesWork, replacement options go out as a good-better-best proposal. Each option can carry rebates shown as an after-rebate price, proof photos, brochures and an estimated yearly energy savings figure that is labelled as an estimate. Rebates have end dates and drop off when they expire, so an old template can't quote last season's program.
Footnotes
-
ENERGY STAR Program Requirements for Central Air Conditioners and Heat Pumps, Version 6.2, Rev. March 2025, definitions and Tables 1 and 2. https://www.energystar.gov/sites/default/files/2025-04/ENERGY%20STAR%20Version%206.2%20Heat%20Pump%20Specification%20Rev.%20March%202025.pdf ↩ ↩2 ↩3
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10 CFR 430.32(c), Energy conservation standards for central air conditioners and heat pumps, paragraphs (c)(5) and (c)(6). https://www.ecfr.gov/current/title-10/chapter-II/subchapter-D/part-430/subpart-C/section-430.32 ↩ ↩2 ↩3 ↩4 ↩5
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10 CFR Part 430, Subpart B, Appendix M1, Uniform Test Method for Measuring the Energy Consumption of Central Air Conditioners and Heat Pumps, including the introductory note on Appendix M2. https://www.ecfr.gov/current/title-10/chapter-II/subchapter-D/part-430/subpart-B/appendix-Appendix%20M1%20to%20Subpart%20B%20of%20Part%20430 ↩ ↩2
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NYS Clean Heat (New York State), "Efficiency Ratings Explained: DOE Appendix M1," fact sheet CHC-CON-ashpM1-fs-1-v2, January 2024. https://cleanheatconnect.ny.gov/assets/pdf/CHC-CON-ashpM1-fs-1-v2.pdf ↩ ↩2
