Glossary
SEER and SEER2
SEER (Seasonal Energy Efficiency Ratio) is the efficiency rating of an air conditioner: how much cooling it delivers over a season for each kWh of electricity it uses. Higher SEER means less consumption for the same cooling. SEER2 is the updated version of the metric, with a test procedure closer to a real installation; SEER2 numbers run somewhat lower than their SEER equivalents.
What SEER is
An air conditioner turns electricity into cooling. SEER is the ratio between the total cooling delivered over a season (in BTU) and the electricity consumed (in watt-hours). It is the equivalent of a car’s miles per gallon: a higher-SEER unit uses fewer kWh to cool the same space.
SEER2 came from an update to the Department of Energy’s test procedure, which now simulates more duct pressure, as in a real home. That is why a unit carries a lower SEER2 number than its old SEER without being less efficient. When comparing units, compare SEER2 to SEER2.
Why it matters in Florida
In Florida, air conditioning is the biggest consumer in the house for much of the year, so every efficiency point turns into real kWh. The southern region of the country also has a higher minimum efficiency requirement for new units than the rest. An old low-SEER unit can be using considerably more than a current one for the same cooling.
But SEER is a lab value. An excellent unit installed with leaky ducts, an incorrect refrigerant charge, or oversized performs far below its label.
Common mistake
Buying the highest SEER you can afford without fixing everything else. Jumping from a very old unit to a modern one justifies the cost; jumping between two modern units a few points apart rarely does, and that money goes further in insulation or duct sealing. We go deeper in what SEER is and why it matters.
Full guide: What SEER means on your air conditioner and why it matters in Florida (2026) →
Updated