A measure of the overall efficiency of a water heater, based on its recovery efficiency, standby loss and energy input as set out in standardized Department of Energy test procedures.

Overall efficiency of a water heater or other appliance. The amount of hot water produced per unit of gas or electricity purchased. The higher the energy factor number, the more efficient the water heater.

The energy factor is the measure of the overall efficiency of a water heater based on the modelâ€™s recovery efficiency, standby losses, and energy input. It is determined by U.S. Department of Energy test procedures and can be used in conjunction with local fuel costs to estimate the annual cost of operation.

Energy Factor is a relative number that is a standard measure for storage of water heating products. It is determined by the Department of Enegry. The number is displayed in a decial equivalent. It is not meant to be a percentage. It represents the efficiency of the water heater. The higher the number, the more efficient it is. It is meant to aid consumers in making comparison shopping easier.

A measure of water heater overall efficiency.

The measure of overall efficiency for a variety of appliances. For water heaters, the energy factor is based on three factors: 1) the recovery efficiency, or how efficiently the heat from the energy source is transferred to the water; 2) standby losses, or the percentage of heat lost per hour from the stored water compared to the content of the water: and 3) cycling losses. For dishwashers, the energy factor is defined as the number of cycles per kWh of input power. For clothes washers, the energy factor is defined as the cubic foot capacity per kWh of input power per cycle. For clothes dryers, the energy factor is defined as the number of pounds of clothes dried per kWh of power consumed.

Overall efficiency of a water heater calculated by testing tank draw efficiency, recovery efficiency and standby efficiency using the DOE protocol.

(EF) The number of complete cycles that a dishwasher or clothes washer operates while using one kilowatt-hour of electricity. For water heaters, it measures the overall efficiency of the heater.