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Dishwashers

The US Department of Energy's ENERGY STAR Program has measured energy efficiency for washing machines and other major appliances, TVs, VCRs, heating and cooling equipment, residential light fixtures, office equipment, windows, and newly built homes. These products were tested for energy efficiency and operational cost factors. See www.energystar.gov/products for Energy Star products, retail stores selling them, and other related information.

Most of the energy used by a dishwasher goes toward heating the water which accounts for approximately 80% of the total energy used. Models that use less water use less energy. There are also several other factors that affect the energy use of dishwashers:

  • Booster Heater: Some dishwashers automatically boost water temperature, while others use built-in heaters to boost water temperature. Each 10 degree reduction in the water heater temperature setting cuts energy consumption from water heating by 3-5%. Make sure that you check the dishwasher manufacturer's instructions for the minimum recommended water heater temperature setting (usually 120 degrees).
  • Energy-Saving Wash Cycles: Most dishwashers today have several different wash cycle selections. If your dishes are only slightly soiled, you can use a "light wash" cycle and save energy by using less water and operating for a shorter period of time.
  • Energy-Saving "No Heat" Drying: Generally, an electric heating element is used to dry dishes at the end of the final rinse cycle. Some new dishwashers offer an energy-saving no-heat drying feature. If you choose to use this feature, room air is circulated through the dishwasher by fans, rather than using an electric heating element to dry the dishes.

Buying a New Dishwasher

  • The rating that you will find on the EnergyGuide label is based on 322 cycles annually on the normal setting. If you plan to buy a model that features other settings that you might use more often, your energy use could vary substantially.
  • There are two dishwasher classifications: compact capacity and standard capacity. Compact models will use less energy, but they will also hold fewer dishes. If you have to use the dishwasher more frequently, you may use more energy.
  • Realize that the manufacturers are not required to test cleaning effectiveness on the same setting that they rate energy-efficiency. Claims about performance may be based on a heavy-duty cycle, while the energy ratings are based on the normal setting.

Installing A Dishwasher

When installing a dishwasher, try to locate it away from the refrigerator. Dishwashers produce heat during operation which, if placed too close to a refrigerator, will increase its energy consumption. If it is not possible to locate the dishwasher away from the refrigerator, you may be able to add extra insulation to the top, sides, and back when it is installed. This will both save energy and reduce noise levels.

Using a Dishwasher for Maximum Energy Savings

  • Try to use the energy-saving cycles whenever possible.
  • If your dishwasher has a booster heater, turn down your water heater thermostat.
  • Use the no-heat dry-air feature on your dishwasher if it is available to you. If it is not available, you can turn the dishwasher off after the final rinse cycle is completed and open the door to allow the dishes to air dry. This will increase drying time, and according to some in the industry increase spotting, but try this method sometime to see how well it works in your machine.
  • Do not pre-rinse dishes. Dishwashers today do a great job cleaning even heavily soiled dishes. Just scrape off food and empty liquids--the dishwasher will do the rest. If you must rinse the dishes first, use cold water.
  • Wash full loads only. You will be surprised to learn that you may save energy by putting dishes in the dishwasher throughout the day and turning it on only once in the evening, rather than washing dishes by hand throughout the day.
  • Load dishwasher according to manufacturer's instructions. Completely fill the racks to maximize energy and water use, while being careful to allow proper water circulation for adequate cleaning.