It’s an acronym for Seasonal Energy Efficiency Ratio, and expressed as a number that typically ranges between 10 and 20; which is a ratio of the cooling output during a typical cooling-season divided by the electric energy input during the same period. Because it is a ratio, there is no unit of measure after the number; however, it could also be termed as BTU’s per watt/hour. 

   It is comparable to the miles-per-gallon rating for a car and, essentially, a higher SEER rating means better energy efficiency. A yellow sticker on the condenser (outside part of a/c system) is affixed at the factory stating the SEER rating of the unit. Starting in 2006, the federal government required that new residential air conditioning systems have a minimum SEER of 13. Pre-2006 systems had SEER ratings mostly between 8 and 12, with the older units being the least efficient. The current minimum SEER is 14.

    A minimum SEER of 14.5 is required to garner an “ENERGY STAR” rating, and possibly qualify for a tax credit or rebate from your local utility. Window a/c units, at the other end of the spectrum, are exempt from the mandate, so their efficiency still hovers around 10. 

    Also see our blog post How can I find out the SEER of my air conditioner?  For advice on when to replace an older system, see our blog post Is it cost-effective to replace an older, low-efficiency air conditioner system with a new high-SEER system?

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  To learn more about heating and air conditioning systems, see these other blog posts:

• How can I find out the SEER of my air conditioner? 

• What is the difference between SEER and SEER2?

• My air conditioner won't turn on. What's wrong? 

• How can I find out the size of my air conditioner? 

• How can I tell whether the condenser (outdoor unit) is an air conditioner or heat pump? 

• Where is the air filter for my central air conditioner and furnace? I can’t find it? 

• Does an old air conditioner use more electricity as it ages? 

• How did homes stay cool in Florida before air conditioning? 

• What is wrong with an air conditioner when the air flow out of the vents is low?

• Why has the thermostat screen gone blank? 

• Why does it take so long to cool a house when an air conditioner has been off for a while? 

• Why is my air conditioner not cooling enough? 

• What are the most common problems with wall/window air conditioners?  

• Will closing doors reduce my heating and cooling costs? 

   Visit our HEATING AND AIR CONDITIONING page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.