SEER vs. EER (and COP)

How do we measure the efficiency of an air conditioner? It all comes down to how much work is done for every watt of power consumed.

1. COP (Coefficient of Performance)

COP is the most direct measurement. It is the number of watts of heat removed divided by the number of watts needed to do the work. If a unit has a COP of 3.7, it means for every 1 watt of electricity, it kicks 3.7 watts of heat outside.

2. EER (Energy Efficiency Ratio)

EER is simply COP translated into BTUs. It is calculated at a specific, extreme condition: 95°F outside, 80°F inside. It tells you how efficient the unit is on the absolute hottest day of the year.

3. SEER (Seasonal Energy Efficiency Ratio)

While EER measures the system at its hardest, SEER measures it over an entire season. It takes into account how efficient the unit is at partial speeds (e.g., when it’s 77°F or 86°F outside).

Because most modern units use variable-speed compressors that excel at these lower speeds, their SEER values are often much higher than their EER values. For example, a unit with an EER of 12.6 might have a SEER of 28.8.

The Verdict

Arguably, SEER is the most important number for your wallet. It tells you how much you will actually spend over an entire summer, not just on the one hottest day of July.

Ready for some high-SEER cooling? Check out Airspool's specifications.