Like its dishwashing relative, most of the energy used by a clothes washer comes from heating water, typically over 90%. And just like the dishwasher, if you reduce the water temperature and the amount of water used, you will save the most energy. Unlike the dishwasher, the clothes washer does not heat its own water, so your water heating strategy is where you will realize a large amount of your savings (see water heating section).
If you are making a new purchase, consider a front-loading washer as this design uses less water. The reason is a top-loading washer tub must be filled for the clothes to be kept wet. To clean the clothes, an agitator then tumbles the clothes in the water. A front-loading washer needs less water and the tub rotates to tumble the clothes in the water eliminating the agitator.
Washing Machine Efficiency
Before making a purchase, check the Energy Guide labels. These labels will give you some idea of how much energy is used by that model washer. Keep in mind smaller models tend to show less energy use but they may not be large enough to meet your needs or cause you to have more loads to run and end up using more energy in the long run.
When shopping for a new washer, look for one that offers a wide number of wash, rinse, and spin options. These options will allow you to tailor your wash to match the type of laundry, specifying water temperature, number of cycles, amount of dryness and so forth.
With pre-soaking and cold- or warm- water detergents, most clothes will be cleaned sufficiently, and cold-water washing can be used in many cases. Badly stained clothes may need pre-spotting as well as a hot water wash cycle to get them clean. Depending on your personal experiences, you may have to try different combinations of detergents and cycles until you are pleased with the results. If your settings permit, always use cold-water rinses as they do the job adequately.
If your washer has a load size control, be sure to use it as the energy use varies directly with the amount of heated water used. Some later models do this automatically. The Department of Energy (DOE) estimates clothes washers use 35 to 40 gallons of water for a complete load.
Washing with full loads in the machine uses less energy per pound of laundry. Your washer's instruction book will indicate the machine's design capacity. Try weighing a few loads until you have the feel for what is a full load. Even with controls that sense the load size, more energy will be used per pound for undersized loads than with a full load.