Washer Modified Energy Factor and Water Factor

For washer Water Factor (WF), Integrated Water Factor (iWF), and/or Modified Energy Factor (MEF/IMEF) ratings by model number:

Energy Star models: http://www.energystar.gov/productfinder/product/certified-clothes-washers/results

Energy Star and non-Energy Star models:  http://www.regulations.doe.gov/certification-data/CCMS-79223002113.html

DEFINITIONS (From the EnergyStar.gov web site)

Water Factor (WF or iWF) is the number of gallons per cycle per cubic foot that the washer uses. The lower the water factor, the more efficient the washer is.

  • If a clothes washer uses 30 gallons per cycle and has a tub volume of 3.0 cubic feet, then the water factor is 10.0.
  • WF is the quotient of the total weighted per-cycle water consumption, Q, divided by the capacity of the clothes washer, C. If a clothes washer uses 30 gallons per cycle and has a tub volume of 3.0 cubic feet, then the water factor is 10.0.

Modified Energy Factor (MEF) is an equation that takes into account the amount of dryer energy used to remove the remaining moisture content in washed items, in addition to the unit's energy used and water heating energy of the washer.

  • MEF is the energy performance metric for ENERGY STAR qualified clothes washers. The higher the MEF, the more efficient the clothes washer is.
  • 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.