What does an air conditioner's SEER rating mean?

An air conditioner's SEER rating refers to the ratio between the amount of cooling it can produce and the amount of electricity it consumes in terms of wattage. A higher SEER rating indicates that an air conditioner has a greater energy efficiency.

Air conditioners produced and sold in the United States after 2005 must have a minimum SEER rating value of 13. As of 2015, this regulation does not include window-mounted units, which typically still have a SEER rating of 10. An air conditioner with a higher SEER rating reduces overall power consumption, with the difference between a SEER 13 and a SEER 9 unit saving up to $300 in annual utility costs.