Energy factor (EF),
Definition of Energy factor (EF):
Measure of the overall (and not relative) energy efficiency of an appliance or equipment. EF is computed differently for different types of devices on the basis of total energy consumed (in active, cycling, and standby modes) and is usually displayed prominently on the item. For a water heater, for example, it is based on three factors: (1) how efficiently the energy from the outlet is transferred to the water by the heating element, (2) what percentage of energy is lost during storage of hot water, and (3) how much energy is consumed in cycling between active mode and standby mode.
Meaning of Energy factor (EF) & Energy factor (EF) Definition