SEER2 and SEER: how the 2023 cooling efficiency rating differs
SEER and SEER2 both measure a heat pump's cooling efficiency over a season. SEER2 is the rating for equipment made from January 1, 2023.
Two ratings, one quantity
Both ratings divide the heat a heat pump removes over a modeled cooling season, in Btu, by the electricity it uses, in watt-hours. Higher uses less electricity.
SEER comes from the Department of Energy test procedure in Appendix M. SEER2 comes from Appendix M1. Every rating made on or after January 1, 2023 must use Appendix M1.
What changed on January 1, 2023?
The test airflow changed. External static pressure is the resistance the indoor blower pushes air against, standing in for the ducts in a house. For a ducted system with its own indoor blower, Appendix M set the test minimum at 0.10 to 0.20 inches of water, by size. Appendix M1 sets it at 0.50 for most equipment. Ductless indoor units are tested at zero in both.
A heat pump's SEER and SEER2 come from different tests, and the test procedure gives no formula that converts one into the other.
Test airflow: DOE Appendix M, Table 4 and DOE Appendix M1, Table 4.
The federal minimums, before and after
The federal efficiency standards changed on the same date, and the new ones are written in SEER2. Each column uses its own test.
| Product class | SEER, made 2015 to 2022 | SEER2, made from 2023 |
|---|---|---|
| Split-system heat pumps | 14 | 14.3 |
| Single-package heat pumps | 14 | 13.4 |
Air conditioners have their own minimums. The higher regional minimums for the Southeast and Southwest apply to air conditioners, not heat pumps.
Federal minimums: 10 CFR 430.32(c)(1), (c)(5), and (c)(6).
SEER2 and EER2
EER2 is one test: cooling output divided by electrical input at 95°F outdoors, at full load. SEER2 is modeled over a whole cooling season. The certified data has no cooling figure at any other outdoor temperature. The methodology lists the cooling fields in the certified data.
SEER2 across certified heat pumps
Each model counts once, by the median of its own pairings. The median SEER2 is 21.35 for mini-split models and 16.0 for central models. The highest model median is 35.1.
| Type | Models | 10th percentile | Median | 90th percentile | Highest |
|---|---|---|---|---|---|
| Mini-split | 5,616 | 19.0 | 21.35 | 24.6 | 35.1 |
| Central | 2,804 | 15.2 | 16.0 | 18.6 | 25.0 |
| All | 8,420 | 15.5 | 20.0 | 24.0 | 35.1 |
What to compare on a quote
A SEER2 belongs to one outdoor unit paired with one indoor unit, and another indoor unit can change it. Compare the SEER2 of the exact pairing on each quote. The quote check shows the certified figures for that pairing.
Where to go next
Browse mini-split heat pumps or central heat pumps, compare 12,000 Btu heat pumps or 36,000 Btu heat pumps, or read how HSPF2 differs from HSPF.