SEER2, EER2 and HSPF2: what each rating measures and how they line up
SEER2 rates seasonal cooling, EER2 cooling at a single hot test condition and HSPF2 seasonal heating, all in Btu per watt-hour. A high cooling rating is only a loose guide to heating: among the 936 rated split systems the ranks of SEER2 and HSPF2 correlate at 0.64, and among the 1,604 mini- and multi-splits at 0.50.
Three numbers, three questions
Each certified match in the ENERGY STAR list carries all three ratings. SEER2 answers how much cooling a system delivers per watt-hour over a typical cooling season. EER2 answers the same question at one demanding test condition rather than across a season, so it is usually the lowest of the cooling figures. HSPF2 answers the heating question: heat delivered per watt-hour over a heating season. Higher is better for all three, and none of them has a fixed maximum.
The figures on this site are the best values among each product's certified matches. A product page shows where the lowest match lands, and the side-by-side view gives both ends of the range.
Typical values by product type
Mini- and multi-splits list higher numbers than split systems on every rating. Their median SEER2 is 22 against 17.1, and their median HSPF2 10 against 8.9. Single-package units, with the outdoor and indoor sections in one cabinet, list the lowest medians of the three types.
| EPA category | Median SEER2 | Median EER2 | Median HSPF2 | Top SEER2 | Top HSPF2 |
|---|---|---|---|---|---|
| Split systems | 17.1 | 11.7 | 8.9 | 29.7 | 12.2 |
| Mini- and multi-splits | 22 | 12.5 | 10 | 35.1 | 16.2 |
| Single-package | 15.5 | 11.5 | 7.7 | 19 | 9.85 |
The tops are far from the medians. The highest SEER2 among split systems belongs to the Toshiba Carrier MCY-MUB0368HS2P-UL at 29.7, and among mini- and multi-splits to the Carrier 37MPRAQ06AA3 at 35.1.
How closely the ratings move together
A rank correlation measures whether products that rank high on one rating also rank high on another, on a scale from minus one to one. Among split systems, SEER2 and EER2 agree at only 0.23: a high seasonal cooling figure says little about the single-condition one. SEER2 and HSPF2 agree at 0.64: the same direction, with plenty of exceptions. Among mini- and multi-splits the link between cooling and heating ratings is weaker still, at 0.50.
The top of the table shows the same thing in plain counts. Of the 93 split systems with the highest SEER2, 25 are also among the 93 with the highest HSPF2. The remaining 68 reach the top on cooling only.
EER2 against SEER2
EER2 never exceeds SEER2 in the cleaned list, and the gap between them differs by type. The median split system lists an EER2 at 65% of its SEER2, the median mini- or multi-split at 58%, and the median single-package unit at 75%.
How many reach the round numbers
Round thresholds are common in product descriptions, so it helps to know how rare they are in the list. An HSPF2 of 10 or more is listed by 172 of the 936 split systems and by 1,019 of the 1,604 mini- and multi-splits; no single-package unit reaches it. A SEER2 of 20 or more is listed by 94 split systems and by 1,346 mini- and multi-splits. On HSPF2 alone, a split system at 10 already sits in the top fifth of its type.
Heating efficiency and cold-weather output
HSPF2 is a seasonal average, and it does not tell directly how much heat a unit lists at 5°F. The data show the two are related, more for split systems than for mini-splits: HSPF2 and the share of 47°F capacity kept at 5°F correlate at 0.77 among split systems and at 0.46 among mini- and multi-splits. A mini-split with a middling HSPF2 can still keep all of its heat at 5°F, and the reverse also occurs. That is why this site shows the 5°F figures next to HSPF2 rather than folding them into one score.
Using the ratings on this site
Every product page places a unit in its size class on all six measures: share kept at 5°F, output at 5°F, COP at 5°F, HSPF2, SEER2 and EER2. Size matters here: small mini-splits list the highest seasonal ratings of all, so ranks are only given within a class of similar certified cooling capacity. The side-by-side view lines up three units on all of them and marks the highest value of each row as a plain fact.
None of the ratings is a cost figure, and this site does not turn them into one. They describe certified matched systems under test conditions, certified as of October 27, 2026.
Sources
- U.S. EPA, ENERGY STAR Certified Heat Pumps (data.energystar.gov, dataset 83eb-xbyy), certified as of 2026-10-27.
- Rating families, ratios, medians, ranks and class bands computed by heatpumpratings.online; see How the ratings are read.