SEER stands for Seasonal Energy Efficiency Ratio. The cooling efficiency of your heat pump or air conditioning system is rated by a SEER number. The SEER is defined as a ratio of the average amount of cooling per unit of electricity used.
Efficiencies of some systems can be as high as SEER 17.0 or more. (Chances are that older homes have units with SEERs less than 10.) Note that it is important to understand that even though the SEER may be high, if the system is not in good condition (for example, leaky ductwork), you will not receive the full value of the efficiency as the air distribution system is not used to determine the SEER rating.
Units with the ENERGY STAR emblem are efficiently designed and offer savings on energy bills without sacrificing performance, features, and comfort.
To learn more about air conditioning efficiency, click here to download this pdf fact sheet from the University of Florida/IFAS.