SEER, Seasonal Energy Efficient Ration, is “The total heat removed from the conditioned space during the annual cooling season, expressed in BTUs, divided by the total electrical energy consumed by the air conditioner or heat pump during the same season, expressed in watt-hours,” according to the Air-Conditioning Heating and Refrigeration Institute. Basically, it’s the heat removed compared to the energy used in the warm months, a measure of the efficiency of a cooling system. The higher the SEER rating the better the system. By comparison, most window air condition units have SEER ratings of 10, while home systems have SEER ratings of 14 or better.