I recently considered the post-dinner party mess in my kitchen and wondered if tossing that mountain of food-glooped dishes in the trash might not be more energy-efficient than actually washing them. Of course, that was the lazy princess in me, not the green warrior hostess that I really am. But I wondered: How does one tackle this scenario in the most eco-friendly manner? Hand wash or dishwasher? Rinse or just scrape? Overload or stack neatly?
Fortunately, before the holiday parade of parties started, I came across a book entitled Consumer Guide to Home Energy Savings (New Society Publishers, 2007), which promises to save me money while I am saving the earth. Hurray! Here is the book’s authoritative and accessible advice for “Using a Dishwasher for Maximum Energy Savings.”
Dishwashing Vs. Hand-Washing
Which method uses less energy? Well, it depends on how old your dishwasher is, what settings you use, and how you would wash the dishes by hand. Studies are showing more and more that, when used to maximize energy-saving features, modern dishwashers can outperform all but the most frugal hand washer.
If you currently wash dishes by hand and fill sinks or plastic tubs with water, it’s pretty easy to figure out whether you would use less water with a dishwasher. Simply measure how much water it takes to fill the wash and rinse containers. If you wash dishes by hand two or three times a day, you might be surprised to find out how much water you’re currently using. Newer dishwashers use only 3 to 10 gallons per cycle.
Scrape, Don’t Rinse
Studies show that most people pre-rinse dishes before loading them into the dishwasher. Modern dishwashers—certainly those purchased within the last 5 to 10 years—do a superb job of cleaning even heavily soiled dishes. Don’t be tempted to pre-rinse dishes before loading; simply scrape off any food and empty liquids and let the dishwasher do the rest. This will save you time as well as water and energy. If you find you must rinse dishes first, get in the habit of using cold water.
When Filling the Dishwasher
Load dishes according to manufacturer’s instructions. Completely fill the racks to optimize water and energy use, but allow proper water circulation for adequate cleaning.
Wash only full loads.
The dishwasher uses the same amount of water whether it’s half-full or completely full. Putting dishes in the dishwasher throughout the day and running it once in the evening will use less water and energy than washing dishes by hand throughout the day. If you find that it takes a day or two to get a full load, use the rinse and hold feature common on most newer models. This will prevent build up of dried-on food while saving time and water compared to pre-rinsing each item. The rinse feature typically uses only 1 to 2 gallons of water.
Use Energy-Saving Options
Pay attention to the cycle options on your dishwasher and select the cycle that requires the least amount of energy for the job. Use the no-heat air-dry feature on your dishwasher if it has one. If you have an older dishwasher that doesn’t include this feature, you can turn off the dishwasher after the final rinse cycle is completed and open the door to allow drying. Using the no-heat dry feature or opening and air-drying dishes will increase the drying time, and it could lead to increased spotting, according to some in the industry. But try this method some time to see how well it works for your machine.
Turn Down the Water Heater Temperature
Since the early 1990s, most dishwashers in the U.S. have been sold with built-in heaters to boost water temperature to 140-145 degrees Fahrenheit, the temperature recommended by manufacturers for optimum dishwashing performance. The advantage to the booster heater is that you can turn down your water heater thermostat, significantly reducing water-heating costs. Resetting your water heater to 120 degrees Fahrenheit (typically halfway between the “medium” and “low” settings) will provide adequate hot water for your household needs.