How can the capacity output of an airconditioner be greater than the power input?
For airconditioners, the measure of energy efficiency is the Energy Efficiency Ratio (EER) for cooling and the Coefficient of Performance (COP) for heating. The EER and COP are defined as the capacity output divided by the power input. Typically, the EER and COP are in the range 2.0 to 3.5 (meaning that the cooling or heating output is 2 to 3.5 times as great as the power input, or an efficiency of 200% to 350%). This is achieved by the use of a refrigeration heat pump which collects internal heat and moves it outside when in cooling mode, or collects ambient heat from outside and moves it inside when in heating mode. The apparent efficiency of heat pumps is high as they can move much more low grade energy in the form of heat than they require as electrical power input into the compressor.
