The ENERGY STAR criteria for clothes washers was changed on February 1, 2013. The new ENERGY STAR criteria require products that meet the definition of Residential Clothes Washer to have a Modified Energy Factor (MEF) of 2.0 or greater and a Water Factor (WF) of 6.0 or lower. Products that meet the definition of Commercial Clothes Washer must meet the ENERGY STAR criteria of a MEF of 2.2 or greater and a WF of 4.5 or lower.
|Product Type||Current Criteria Levels (as of February 1, 2013)|
|ENERGY STAR Residential Clothes Washer||MEF ≥ 2.0
WF ≤ 6.0
|ENERGY STAR Commercial Clothes Washer||MEF ≥ 2.2
WF ≤ 4.5
|Federal Standard||MEF ≥ 1.26
WF ≤ 9.5
1MEF = modified energy factor
2WF = water factor (gallons per cycle per cubic foot)
Only front and top loading clothes washers with capacities greater than 1.6 ft3 and less than 6.0 ft3; and are not defined as Combination All-In One Washer-Dryers or Residential Clothes Washers with an Optional Dry Cycle are eligible for ENERGY STAR Qualification.
Energy Factor (EF) is the previous energy performance metric for clothes washers. It is the quotient of the capacity of the clothes container, C, divided by the sum of the machine electrical energy for the mechanical action of a cycle, M, and the water heating energy required for a cycle, E. The equation is shown here:
|M + E|
The water heating energy may be from a gas or electric water heater. The units are cubic feet per kWh per cycle, ft3/kWh/cycle. The higher the value, the more efficient the clothes washer is.
Modified Energy Factor, MEF, is the energy performance metric for ENERGY STAR qualified clothes washers and all clothes washers as of February 1, 2013.
This metric has the same units as the energy factor (EF): ft3/kWh/cycle. MEF is the quotient of the capacity of the clothes container, C, divided by the total clothes washer energy consumption per cycle, with such energy consumption expressed as the sum of the machine electrical energy consumption, M, the hot water energy consumption, E, and the energy required for removal of the remaining moisture in the wash load, D. The higher the value, the more efficient the clothes washer is. The equation is shown below:
|M + E + D|
Water Factor, WF, is the present water performance metric that allows the comparison of clothes washer water consumption independent of clothes washer capacity. Manufacturers must submit their water consumption factors with their ENERGY STAR qualified clothes washers.
WF is the quotient of the total weighted per-cycle water consumption, Q, divided by the capacity of the clothes washer, C. The lower the value, the more water efficient the clothes washer is. The equation is shown below:
The federal EnergyGuide label on clothes washers shows annual energy consumption and cost. These figures use the energy factor, average cycles per year, and the average cost of energy to make the energy and cost estimates. The Energy Factor, Modified Energy Factor, or Water Factor may not appear on the EnergyGuide label.