Dishwashers have come a long way since this 1921 model, which was designed mainly to help minimize the drudgery of housework. But today's sleek models are also designed with water conservation in mind. Bettmann/Bettmann Archive/Getty Images hide caption
Dishwashers have come a long way since this 1921 model, which was designed mainly to help minimize the drudgery of housework. But today's sleek models are also designed with water conservation in mind.Bettmann/Bettmann Archive/Getty Images
When I was a kid, my mom always told me to rinse the dishes before putting them in the dishwasher. This was especially true for dishware with tacky residue. Peanut butter, cream cheese, frosting — these adversaries were simply too powerful for the dishwasher's meek cleanse. Today, still harboring a distrust of dishwashers, I tend to wash my dishes by hand.
But I often wonder about the consequences of my sponge-scrubbing ways — am I wasting water by avoiding the dishwasher, or saving it?
"I think it's generally recognized that washing by machine would involve less water," says Ed Osann, water efficiency project director for the Natural Resources Defense Council. "In part, it comes down to someone's washing technique."
According to Osann, when people wash by hand, they often use the same method. They fill one sink basin with sudsy water for soaking and run the faucet in the other basin for rinsing. That's an efficient way to do dishes from a time perspective, but not from a water perspective. The Department of Energy sets standards that a full-size dishwasher can use no more than five gallons of water per cycle, and a compact dishwasher no more than 3.5 gallons. Osann says that's probably less water than most people's dishwashing styles use. Because heating water requires energy, using less water also translates to being more energy efficient.
Dishwashers today are not my mother's dishwasher, according to Jennifer Amann, buildings program director for the American Council for an Energy-Efficient Economy. Dishwashers might have used eight to 10 gallons per cycle 15 years ago, making them, in Amann's words, "water hogs."
But newer dishwashers have adopted a number of design changes to up their grime game. Dishwasher designers are continually refining the arrangement of dish racks, to optimally expose plates and utensils to the internal spouts of water that fill the machine during a cycle. But even more importantly, dishwashers now have sensitive technology to detect how murky the water in the machine is. A cycle begins using just a little water. After washing, the machine detects how murky the water is as a measure of how much food and grime are coming off the dishes. If the water is still cloudy, the machine adds a little more water, washes some more, and then tests again, repeating the incremental water increase until the water is clear.
Today consumers can buy dishwashers that use even less water than the Department of Energy standards require. Energy Star, an independent evaluator that partners with the Environmental Protection Agency to certify products as energy efficient, sets even lower water use targets for dishwashers. Consumer Reports and the American Council for an Energy Efficient Economy also provide energy-conscious recommendations to consumers.
Today, both Osann and Amann say people should scrape plates clean, rather than rinsing them, before putting the plates in the dishwasher. For small households that tend not to fill the dishwasher quickly, Amann suggests the rinse cycle, which generally uses only half a gallon of water and still effectively cleans dishes that haven't been sitting in the dishwasher too long. (I tried this approach. My dishwasher's rinse cycle worked well on peanut butter, but remnants of Greek yogurt stubbornly stuck around.)
For those who can't break their manual scrubbing habits, Osann recommends filling up a large metal pot, rather than filling up the sink, to do washing in. Nonetheless, he makes a final plug for the dishwasher. "People could be more cognizant of their use of water while washing dishes by hand. Are people likely to do that when friends are over for Thanksgiving? Probably not."
In other words, in the spirit of the holidays, it might be appropriate to give the machine a little trust.
The restroom at my office has electric hand dryers with little plaques that read, "Thanks for helping us save trees." Is my company really doing the planet a favor by ditching paper towels? Generating electricity doesn't strike me as a clean endeavor.
Both hand dryers and paper towels carry an environmental cost, so the Lantern's peers typically advise folks to wipe their hands on their trousers. But if you fancy yourself too classy to walk around in damp pants, then hand dryers are, indeed, the greener option—not because they necessarily prevent deforestation, but because they actually use less energy once everything's taken into account.
Calculating the impact of electric dryers is easy enough. A fair amount of energy goes into manufacturing metal goods with mechanical parts. But the fact that dryers last so long—typically between seven and 10 years—means that production accounts for a negligible part of the hardware's total energy consumption. The vast majority of a dryer's environmental toll stems from the electricity it requires; a typical warm-air dryer uses around 2,200 watts of power when switched on, plus about 2 watts while in standby mode. If you dry your hands for 30 seconds (as opposed to the 43 seconds required to get them fully water-free), then you're using about 0.018 kilowatt-hours of electricity. Do that three times a day for a year, and your insistence on dry-hand decorum has run you 19.71 kWh of electricity, which translates into roughly 26.61 pounds of carbon dioxide emissions.
There are several variables that can complicate the hand-dryer equation. The first is the emergence of a new generation of dryers, such as the XLerator and the Dyson Airblade, that claim to be at least 80 percent more efficient than their forerunners (due in part to much shorter drying times). You also need to consider how your local power grid generates its electricity—the more coal that is used, the more carbon a dryer will generate per kilowatt-hour. (As always, you can check out your grid's fuel mix by using the Environmental Protection Agency's Power Profiler tool.)
These complications, however, pale in comparison with those that bedevil the life-cycle assessment of paper towels. The main problem here is that there's so much variation in how rolls are produced, starting with how the trees are harvested. The vast majority of American paper towels begin life in well-managed commercial timberlands, where trees are replaced after harvest, so deforestation isn't a pressing issue. But one must account for the fossil fuels expended on machinery and log transport. Then there is the energy-intensiveness of the pulping process, which can result in the emission of harmful pollutants into nearby waterways. One must also consider the cost of trucking the towels from manufacturer to client, a data point that will vary widely according to the restroom's distance from the paper mill. (Yes, dryers must be transported in this manner, too, but far less frequently, given how long each one lasts.)
On top of these obvious costs, there are some that are less apparent to the average consumer. Facilities managers often complain that paper-towel dispensers result in increased maintenance work, as restroom users are regrettably messy when it comes to disposing of used towels. That means more cleaning chemicals must be manufactured and used, their plastic bottles disposed of. Paper towels also require frequent replacement of plastic trash-can liners, which must be carted off to the landfill when full.
Paper towels can be environmentally cleaner if composed of recycled material—the EPA claims that the production of recycled paper requires 40 percent less energy than making virgin paper. It should be noted, however, that paper towels are not themselves recycled and thus end up in the trash stream after a single use.
Given all the variables involved in calculating the environmental cost of paper-towel usage, the Lantern can't really toss out a simple carbon-emissions figure. When the Climate Conservancy analyzed this issue at the behest of Salon, it came up with a figure of about 0.123 pounds of greenhouse-gas emissions per paper-towel "session"—that is, the researchers assumed that a hand-washer uses two towels to dry off. The range for hand dryers, by contrast, was between 0.02 pounds and 0.088 pounds, depending on wattage and drying time. It's not clear, however, whether the towels in question contained recycled material.
Franklin Associates reached a similar conclusion in 2002, when it conducted a life-cycle assessment at the behest of Excel Dryer, the company behind the XLerator. The study, which took into account the energy used both to mine raw ores and to chop down trees, concluded that recycled towels result in an energy expenditure of 460 kilojoules per use, versus 222 kilojoules per use for a standard dryer. But like their colleagues at the Climate Conservancy, the authors assumed that each washroom user went through two towels. By halving your consumption to a single sheet, then, you can essentially erase any difference between towels and old-school dryers. (The newfangled dryers still come out way ahead.)
The bottom line is that hand dryers will be the greener choice in about 95 percent of circumstances. If the choice is between using a tiny corner of recycled towel versus a 2,400-watt dryer, then the Lantern can see how the towel will win. But dryers get the nod in most other scenarios, particularly if the dryer is rated at less than 1,600 watts. (Check the specs plate on the side if you're really curious.)
But, to paraphrase Darth Vader from Star Wars, don't be too proud of using those technological marvels we've created. Opting for a hand dryer over towels hardly earns you an environmental halo, as the net difference in long-term carbon emissions is minuscule at best. It's useful to think about everyday behaviors, but let's not lose focus on big-picture stuff.
Is there an environmental quandary that's been keeping you up at night? Send it to firstname.lastname@example.org, and check this space every Tuesday.