Since 2023, new US equipment carries SEER2, EER2, and HSPF2 ratings under tougher test procedures. SEER2 numbers run lower than old SEER for the same hardware. ENERGY STAR requires SEER2 15.2+ for split AC and HSPF2 7.8+ for heat pumps in most configurations.
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SEER2 Efficiency Guide
SEER2, EER2, HSPF2, and what upgrades actually pay back.