Energy Efficiency Ratio (EER)
The cooling output of an air conditioner divided by its electrical input at a specific outdoor temperature (usually 95 degrees F). Higher EER means more efficient cooling. Being replaced by SEER2.
Why It Matters
EER measures peak-condition efficiency, while SEER2 measures seasonal average. Both matter: EER tells you performance on the hottest days when you need cooling most.
Related Tools
Related Terms
SEER2 (Seasonal Energy Efficiency Ratio 2)
The updated cooling efficiency metric for air conditioners and heat pumps, measured under 2023 DOE test procedures with higher external static pressure (more realistic conditions).
COP (Coefficient of Performance)
The ratio of heating or cooling output to electrical energy input for a heat pump. A COP of 3.0 means the system produces 3 kWh of heat for every 1 kWh of electricity consumed.