Washing Machines, Loads, and Temperature Settings
Horizontal-axis (H-axis) washing machines, also called front loaders, are far more energy-efficient than conventional top-loading, vertical-axis machines. Some soaps and detergents perform well at lower water temperatures and should be used where appropriate. Temperatures should be checked with an accurate thermometer, and equipment should be adjusted as needed to provide the lowest acceptable temperature. Using equipment efficiently means ensuring that washing machines and dryers are operated with full, rather than partial, loads. To reduce energy use by clothes washers, hot water heaters or boilers should be operating efficiently.
Heat Recovery Opportunities for Heating Water
One cost-effective option for reducing energy costs associated with heating water is to implement heat recovery efficiency measures. Energy that would be otherwise lost can be recovered and used for other purposes, such as heating outdoor air used for ventilation, space heating, and water heating. When the recovered heat is of a sufficiently high temperature, it can be effectively used to heat water.
A good source for recovered heat is a water-cooled refrigeration system. Water goes through a heat exchanger and transfers heat directly to where it can be used (i.e. the laundry) or to a hot water tank. The recovered heat preheats fresh water before it enters the domestic hot water tank, lowering the amount of energy needed to heat the water to the necessary temperature. This process works well for laundries and dishwashers. Also, hot drain heat exchangers or heat pumps can be installed to recover heat from drain water.
Laundry Dryer Efficiency
Unlike most other types of appliances, energy consumption does not vary significantly among comparable models of dryers. A dryer with a moisture sensor will automatically shut off when clothes are dry. Not only will this save energy, it will reduce the wear and tear on laundry from over-drying. The most efficient dryers have moisture sensors in the drum for sensing dryness, while most only infer dryness by sensing the temperature of the exhaust air. Compared to timed drying, hotels can save about 10 percent with a temperature-sensing control and 15 percent with a moisture-sensing control.
Dryers with a cool-down period in their drying cycle, sometimes known as a "perma-press" cycle, also save energy. In the last few minutes of the cycle, cool air, rather than heated air, is blown through the unit to complete the drying process.
Building Toolbox - Laundry Equipment. U.S. Department of Energy, Energy Efficiency and Renewable Energy. www.eere.energy.gov
Energy Star. Building Improvement. www.energystar.gov