Air conditioners ranked on certified efficiency, and the federal data that went missing

What can you use if you are shopping for central AC?

Two honest routes remain, and neither is a ranking of cooling-only central equipment.

The first is that the market has largely moved: The only central cooling data ENERGY STAR currently publishes is the cooling side of certified heat pumps — 8,465 deduplicated families carrying SEER2 and EER2 measured under exactly the same DOE Appendix M1 procedure a cooling-only unit would be.

A heat pump is an air conditioner that can also run in reverse; in 2026 it is increasingly what is actually installed as central cooling equipment.

Those ratings are ranked by capacity band on our heat pump page, where the median certified family rates 21.0 SEER2 and 12.25 EER2.

The second is the rule that decides what you may legally have installed, which is a different question from which unit is most efficient and is frequently the one that actually binds.

The federal minimum for a split-system air conditioner is not national — three regional regimes apply, and installation, sale and manufacture are three separate prohibitions with different dates. That is covered in full, with the regulation quoted, at one country, three efficiency standards. It is not repeated here.

Are all certified room air conditioners variable-speed?

Yes, and all use R-32. HyreHVAC calculation: of the 230 distinct certified rating profiles in the federal room air conditioner file, 230 are variable-speed and 230 use R-32. Not most.

All of them. There is no single-speed compressor and no R-410A anywhere in the ENERGY STAR certified room air conditioner market as of September 5, 2026.

Both of those were live variables in this category a few years ago, and both are now settled at the certified end of the market.

HyreHVAC analysis: the plausible reading is that the two moved together — R-32 has a global warming potential of 675 against R-410A’s 2,088, and the variable-speed compressor is a large part of how a window unit clears the ENERGY STAR CEER thresholds at all.

We cannot demonstrate the causal link from this file, and we do not claim it.

What the file does establish is that the transition in this category is complete rather than in progress, which is not what the shopping advice on this subject currently says.

The practical consequence is that "look for variable speed" is no longer a way to choose between certified room air conditioners — it only separates certified units from uncertified ones.

Within the certified set the useful discriminator is CEER against the class median, and the class matters, because the federal standard sets a different floor for each.

Why are the tables split by federal product class?

The DOE product class is written into every record — capacity range, whether the unit has louvered sides, and whether it can run in reverse to heat.

It is not our segmentation and it is not a marketing category: it is the class the federal minimum standard is set against, so two units in the same class are held to the same legal floor and are genuinely comparable.

ENERGY STAR sets its own CEER thresholds on the same structure, and states that certified units are 19–36% more efficient than the federal minimums.

HyreHVAC calculation: the median across all 230 certified profiles is 15.0 CEER, but the class medians run from 13.3 to 15.0.

Ranking across classes would put every reverse-cycle and small louvered unit at the top and tell a reader nothing about the unit that fits their window.

The largest class — class 3, without reverse cycle, with louvered sides, and 8,000 to 13,999 btu/h — holds 116 of the 230 profiles on its own.

One further note on reading the tables. 22 of the 230 certified profiles can also heat, and 68 meet ENERGY STAR’s separate Most Efficient criteria. The "below federal minimum by" column is EPA’s own certified figure for each model, not our arithmetic.