Residential clothes washers include both front-loading and top-loading machines. Most clothes washers are classified as “standard” size, which means that they have capacities of 1.6 cubic feet or greater. “Compact” clothes washers have capacities of less than 1.6 cubic feet.
DOE finalized standards for residential clothes washers in 2012, and they took effect in 2015. A second tier of standards for top-loading washers took effect in 2018. The standards, which were based on a consensus agreement between manufacturers and efficiency advocates, specify minimum energy and water efficiency levels. The metric for energy efficiency is integrated modified energy factor (IMEF), which is expressed in terms of cubic feet of washer capacity per kWh of energy consumed per cycle. IMEF incorporates machine electrical energy consumption, hot water energy consumption, the energy required to remove the remaining moisture in the clothes, and any standby or off mode energy consumption. The metric for water efficiency is integrated water factor (IWF), which is expressed in terms of gallons of water consumed per cubic foot of washer capacity. A higher IMEF indicates better energy efficiency, while a lower IWF indicates better water efficiency. The current standards specify minimum IMEF levels of 1.57 and 1.84 for top-loading and front-loading washers, respectively, and maximum IWF levels of 6.5 and 4.7.
Clothes washer efficiency improvements can be achieved through advances in mechanical technology (efficient motors); reductions in the amount of water consumed to clean a given volume of laundry; and higher spin speeds to remove more moisture from the clothes at the end of the cycle, which reduces clothes dryer energy consumption.