SEER2 explained: what AC efficiency ratings actually mean for your bill

SEER2 is the federal efficiency rating for cooling equipment — the honest version of the old SEER number, measured under realistic duct pressure since 2023. Understanding it takes two minutes and can save you thousands.

The two-minute version

• SEER2 = cooling delivered per unit of electricity across a season. Higher is better, roughly linearly: 16 SEER2 uses about 14% less energy than 14 SEER2 for the same cooling.
• Most homes still run 10–13 SEER (old scale) equipment. Today's baseline is ~14 SEER2; good equipment is 16+; premium variable-speed systems run higher still.
• Ratings are lab numbers for NEW equipment. Real units lose roughly 2–3% efficiency per year without meticulous maintenance — a 15-year-old '13 SEER' unit may effectively perform like 8–9.

When the upgrade pencils

Efficiency is worth the most where cooling hours and electric rates are high. A 3.5-ton system in California's Central Valley (roughly 1,400 full-load cooling hours at ~40¢/kWh) can waste well over $1,000 a year at old-unit efficiency versus a modern 16 SEER2 system. In Florida and Texas, 2,000+ cooling hours do the same damage at lower rates. In mild coastal climates, the payback is slower — which is exactly why the calculation should be run for your home, not a national average.

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