The U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy requires the industry to thoroughly test and report the energy usage of all appliances. Clothes washer energy consumption is measured in two ways.

• MEF (Modified Energy Factor) measures the energy used during the washing process, including washing machine energy consumption per cycle, hot water energy consumption, and dryer energy required for the removal of the remaining moisture in the wash load—the higher the MEF, the more energy efficient the clothes washer. At the time of this writing, ENERGY STAR® qualified models manufactured after January 2007 must meet the current minimum MEF standard of 1.72.

• WF (Water Factor) measures the gallons of water used per cycle per cubic foot (for example, a 3.0 cubic foot washer using 27 gallons per cycle has a water factor of 9.0). The lower the WF, the less water the machine uses. By January 1, 2011, ENERGY STAR® qualified washing machines will be 59% more efficient than mandated energy standards and will have a maximum WF of 6.0 (U.S. Department of Energy, March 2008).

The yellow EnergyGuide labels that appear on all new washing machines include information on the energy usage of the product, energy usage comparisons with similar models, and estimated annual operating costs. The EnergyGuide label was updated in 2007 to feature estimated annual operating costs more prominently (Federal Trade Commission, August 2007). When comparing EnergyGuide labels, be sure to look at the tub capacity printed on the label. Choose a washer with the tub capacity that meets your needs—standard sizes for residential use typically range anywhere from 2-3.5 cubic feet.

Source: Wendell A. Porter, Hyun-Jeong Lee, and Kathleen C. Ruppert, Energy Efficient Homes: Laundry Area UF/IFAS FCS3260, 2008

Additional Resources

UF IFAS Energy Efficient Homes: Laundry Area - http://edis.ifas.ufl.edu/FY1030

ENERGY STAR®. (n.d.-a) Save Money, Energy and Water—Choose ENERGY STAR Qualified Clothes Washers. Retrieved May 7, 2008 from:  http://energystar.gov/index.cfm?c=clotheswash.clothes_washers_save_money.

ENERGY STAR®. (n.d.-b) Save Time and Your Clothes with an ENERGY STAR Clothes Washer. Retrieved May 16, 2008 from:  http://energystar.gov/index.cfm?c=clotheswash.clothes_washers_save_more.