The Energy Efficiency Ratio (EER) of an HVAC cooling device is the ratio of output cooling energy (in BTU) to input electrical energy (in watts) at a given operating point. EER is normally calculated with a 95 °F outside temperature and an inside (return air) temperature of 80 °F and 50% relative humidity.
Similarly, The Seasonal Energy Efficiency Ratio (SEER) rating of a unit looks at an air conditioner a bit more granularly—calculating the cooling capacity during a typical cooling-season (rather than all-time) divided by the total electric input during the same period.
