SEER and air conditioner efficiency
Cooling efficiency for air conditioners is indicated by a SEER (Seasonal Energy Efficiency Ratio) rating, which tells you how efficiently the unit uses electricity.   The rule for saving is simple—the higher the SEER rating, the less energy you use and the more you save.
The minimum efficiency standard for units installed in new homes is currently 13 SEER.  Most air conditioners manufactured before 1992 had SEER ratings below 7. Air conditioners manufactured today have SEER ratings that range from 13 to as high as 26 in some units.