This is the standardized method used by the HVAC industry to rate the efficiency of residential air conditioners and heat pumps. The minimum efficiency rating of air conditioners and heat pumps manufactured in the United States must have an SEER of at least 13.

SEER ratings today range from 13 to 18.  The rating can be likened to the gas mileage of an automobile, the higher the SEER rating, the more energy efficient the equipment.

A SEER rating of 15 means that 15 BTU's of heat is removed for each watt of electricity used.