Method Of Dishwashing Determines Energy Use

Q. Which is more energy efficient, washing dishes by hand or using a dishwasher? B.H., Cheney

A. It depends on the dishwasher, how you use it, and the way you hand-wash the dishes. Keep in mind that the second largest use of energy in home is for heating water.

According to a study conducted by Ohio State University, an average dishwasher uses about 10 gallons of water, where it takes about 16 gallons of water for the same amount of dishes washed by hand. But if the dishes are hand-washed using the sink or a dish pan for washing and rinsing, then it requires less water than the dishwasher. Newer, efficient dishwashers use as little as 5 gallons per cycle which means they consume less energy to heat the water.

Water heating accounts for about 80 percent of the energy used by dishwasher. Since a 140-degree temperature is recommended for better dishwashing performance, most dishwashers now have an internal water heater called a booster heater, which raises the water temperature to 140 degrees when the dishwasher is in use. This allows you to set the household water heater temperature to 120 degrees to increase the efficiency of the heater.

Here are a few tips to save energy and water on dishwashing:

Dishwasher: Wash only full loads. Avoid pre-rinsing. Load items properly. Use the “no heat” dry cycle, or open the door to air dry the dishes. Use the energy-saving cycle whenever possible.

Handwashing: Use the sink or dish pan for washing and rinsing dishes. Install a low-flow kitchen sink aerator on the faucet.

For a free factsheet - “Using Appliances Efficiently” - call our Energy Hotline at (800) 962-9731 or 324-7980 in Spokane.

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