Explainers
Seven short reads on what the heat pump ratings mean, each built on the full ENERGY STAR list certified as of October 27, 2026. Every number in them is calculated from the same data as the rest of the site.
- Cold-climate heat pumps at 5°F
1,966 of 2,613 rated products carry the EPA cold-climate designation; 533 list at least as much heat at 5°F as at 47°F.
- SEER2, EER2 and HSPF2 explained
SEER2 and HSPF2 ranks agree only loosely: 0.64 among split systems and 0.50 among mini-splits.
- Variable-speed, two-stage and single-stage
Variable-speed split systems keep a median 83% of their 47°F capacity at 5°F; one- and two-stage units 52%–55%.
- R-454B, R-32 and R-410A
R-454B is now the most common refrigerant: 1,150 of 2,613 rated products.
- One outdoor unit, many ratings
For split systems the same outdoor unit's SEER2 typically varies by 1 across its certified matches, and by up to 13.1.
- Size classes: efficiency and 5°F output
The 6,000 Btu/h mini-split class has the highest median HSPF2 (14.6); among split systems the 2-ton class keeps the most heat at 5°F.
- Same ratings under different brand names
58% of rated products are listed under more than one brand name; one outdoor unit appears under 54.