Robin Green

Your daily chores: Save money and electricity, avoid hand washing the dishes!

You might think doing the dishes by hand saves energy compared to using an ENERGY STAR dishwasher. But energy saving dishwashers use far less hot water than most people who wash dishes themselves. Use your dishwasher, and regain half a month of your life a year!

Efficient dishwashers can wash your dishes with less water and electricity than if you try to clean them by hand. That's what appliance manufacturers tell us. But is this really the truth?

I used to have my doubts. I can clean the dinner dishes by hand using barely a gallon of water, while energy efficient dishwashers use around 4 gallons per load, plus all that electricity to heat the water and slosh it around.

I would like to share my tips for cleaning dishes by hand with as little water and energy as possible. But don't forget that, for most of us, efficient dishwashers are a better choice than hand-cleaning, as long as you use the dishwasher properly.

If you observe a typical American wash dishes by hand, it's not hard to see why a dishwasher wins over hand washing almost every time. Some people let the water run continuously as they wash; some fill a sink with warm water and run cold water in the second sink for rinsing; some are continuously squeezing dish soap into a scrub brush. When you add up all the energy that is required for warming the water, manufacturing the dish soap, and even the energy for treating and pumping the water to your home, it can add up to considerably more than you think.

When people think about a dishwasher, they tend to think of the electricity used to pump water around inside. They might think that they'll save all that energy if they wash dishes by hand. It turns out that pumping the water uses less energy than heating the water - only 20% of the total, compared to 80% for heating when you consider the heating that takes place in your hot water tank and in the dishwasher proper.

You might think that hand-cleaning would at least save you the remaining 20% of the energy used by the dishwasher. But since people typically use much more water than energy saving dishwashers, the end result is more energy use in hand-cleaning than when using a good quality dishwasher. (Older dishwashers may use up to twice as much water as newer models, so it is possible to do better by hand than that old avocado-colored 1970's model!)

Energy efficient dishwashers are able to wash dishes with a very small volume of water by doing two things you cannot match when hand washing: Heating the water to 140F - too hot for your hands - because hot water does a better job of getting grease and food residue off dishes; and circulating the water at high pressure, which blows waste off plates and cutlery more effectively than you can do with a scrub brush, using a tiny amount of water to do so.

Where ENERGY STAR dishwashers are less efficient is where people sabotage the energy saving features of the dishwasher, by pre-rinsing, keeping their hot water tank temperature too high, using too heavy duty a cycle, using the rinse-and-hold or heated-dry features, running the unit half empty, and using too much dishwasher detergent.

It is possible to outperform a dishwasher in terms of energy efficiency. Whether it's worth your while is open to debate. Consider the fact that energy efficient dishwashers with an ENERGY STAR logo can do a full load of dishes for the energy equivalent of less than 1.55 kilowatt hours (kwh) of electricity (that includes both the energy for mechanical and heat). At an approximate cost of $0.10 per kilowatt hour, and assuming you clean the dishes by hand using cold water, the most you would save is about 15 cents per load.

And remember, we're talking a full dishwasher load - which can accommodate 6-8 place settings as well as 6 serving pieces. Assuming bread plate, dinner plate, bowl, cup and saucer, knife, fork and spoon, that's about 72 items cleaned, so you'll save around one fifth of a cent per item if you wash by hand and use no energy.

But let's suppose that you want to wash dishes by hand. I kind of like cleaning dishes; it's good contemplation time, plus it cleans my fingernails! How can you wash dishes by hand using as little energy as possible? Here are my pointers:

Never drain 'gray' water. After you've cleaned a load of dishes by hand, or rinsed vegetables, leave the water in the sink. Use this gray water to pre-rinse the dirtier dishes to remove most of the grease and other food residues. That way, when it comes time to clean, you won't need as much water.

Never let the tap run for extended periods. Turn it on for short bursts, only when you really need that extra water.

Use a faucet aerator. You can rinse dishes effectively while saving water using an aerator, which injects a stream of air into the water.

Use cold or just lukewarm water. Where I live in Costa Rica, no one washes dishes in hot water, but granted, the cold water comes out at a balmy 70F. This just goes to show that you can, at the very least, clean in lukewarm rather than hot water.

Start washing with a hand's depth of warm water in the sink. Wash dishes in that, and rinse in a second sink with cold water. Otherwise stack the dishes after cleaning, and then rinse them all in cold water after you finish the soap wash.

Just like your mom may have taught you, start by cleaning the cleanest dishes - glasses, cups, cutlery, plates, leaving the dirty pots and pans for last.

Using these tips I can clean dishes from a meal for four people in about three liters of fresh water. But why would I want to do this? And how many of us can really outperform the efficiency of a good, late model dishwasher?

If you think you can beat a new dishwasher, here's some research that modern efficient dishwashers not only clean dishes using less energy, water and detergent than people do, but also do a better job of getting the dishes clean.

A University of Bonn study asked over 100 subjects to clean 12 place settings of dirty dishes. Each subject was given the run of a kitchen and taped by camera; energy, water and dish soap use were measured. The dishes were then inspected for cleanliness according to a recognized dishwashing standard. The same dishwashing setup was tried with modern efficient dishwashers.

The ENERGY STAR dishwashers consumed 15 liters of water and 1-2 kwh of energy to clean 12 place settings, while only two of the over 100 subjects consumed less than 20 liters of hot water. (Forty of the hand-washers used more than 100 liters of water each!). However, 70 of the subjects did succeed in using no than 2 kwh of energy - and a quarter of the test subjects used 1 kwh or less.

From this study we can conclude that you can match the efficiency of energy efficient dishwashers, or even beat their performance slightly. But the energy saved is so small that it doesn't justify the extra effort. The human hand-washers took at least 40 minutes to do the load, while the energy efficient dishwashers needed only a quarter hour of human effort for loading and unloading. Considering that the US EPA/DOE rates dishwasher efficiency based on 215 loads of dishes per year, a typical hand washer would be adding about 89 hours of effort to their year. That's more than two weeks of 9-to-5 work used up!

You would do better to save that work and look at other things in your house you can do to conserve energy. Imagine how efficient your home would be if you devoted an extra 89 hours a year towards caulking, insulating, sealing air leaks, and changing light bulbs to more energy saving bulbs. Or how much more relaxed you'll be by using your dishwasher. You just gained two more weeks of time off!

Article Tags: Energy Efficient Dishwashers, Hand Washing, Efficient Dishwashers, Hand Using, Energy Efficient, Wash Dishes, Cold Water, Dish Soap, Energy Saving, Energy Star, Place Settings

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