SEER2 (Seasonal Energy Efficiency Ratio 2)
The current federal test metric for AC and heat pump cooling efficiency — seasonal cooling output divided by electricity used, measured under the stricter 2023 test procedure. Higher SEER2 costs more up front and less every summer.
The longer answer
SEER2 replaced SEER under the same 2023 federal test revision as HSPF2 — numbers read lower for the same hardware. A 16 SEER2 unit is roughly equivalent to an 18 SEER in old terms. Compare like to like when evaluating equipment.
In heat pump systems, SEER2 and HSPF2 are independent ratings on the same unit — cooling efficiency and heating efficiency can land at different tiers. For Seattle homeowners, HSPF2 usually matters more because the heating season runs longer, but both numbers belong on any equipment comparison.
The Seattle angle
Seattle's historically mild summers mean SEER2 tier matters less than HSPF2 for total annual savings — but warming summers and more AC adoption are changing that calculus.
Guides that use this term
Where this decision happens
Nearby in the glossary
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