SEER2 (Seasonal Energy Efficiency Ratio 2) is the federal metric for residential air conditioning and heat pump cooling efficiency, in effect since January 1, 2023. It replaced the older SEER metric with stricter test conditions — most notably testing at higher external static pressure that better reflects real-world duct restrictions.
The number expresses BTU of cooling output per watt-hour of electricity over a simulated cooling season. Higher = more efficient. The federal minimum for the southern region (which includes SC) is currently SEER2 14.3 for split systems.
For Lowcountry homes where cooling runs 6-7 months per year, every SEER2 point delivers meaningful operating-cost savings. SEER2 16-18 is the typical sweet spot for value. SEER2 20+ exists but has diminishing returns.
SEER2 ratings translate roughly to the older SEER scale by multiplying by 1.05 (so SEER2 15 ≈ old SEER 15.75).
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