What are 'high-efficiency' dryers?

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So your old clothes dryer is on its last leg -- or its last load -- and you're looking to replace it. You'd really like a dryer that will save you a little money and energy, right? Maybe you've already begun to research dryers online or at your local appliance store. The high-efficiency washers and dryers probably caught your eye with their sleek lines, high-tech interfaces and special "eco" features. It seems like these appliances can do everything but fold up your laundry and put it away. And because these appliances are labeled as "high-efficiency," they promise the energy and money savings you're looking for.

But what does high-efficiency mean? How do you figure out which dryer is the most efficient? The efficiency of a dryer is based on how well it removes moisture from clothes using a given amount of energy, or how many pounds of clothing can be dried per kilowatt-hour (kWh) [source: Bansal, Flex Your Power]. Here are some of the things that can affect the efficiency of your dryer:

  • How much water is left in the clothes by your washing machine
  • Air temperature inside the dryer
  • Ambient humidity inside the dryer (which changes as the clothes dry)
  • Flow of air across the clothes

All dryers manufactured in the United States have to meet certain minimum efficiency requirements set by the Department of Energy [source: Eastment]. However, energy-efficient dryers have to exceed those standards. According to EnergyStar, the program that certifies energy-efficient appliances, a high-efficiency dryer should be at least 20 percent more efficient than a regular dryer [source: Taddonio].

Considering that of all the appliances in the American household, the dryer is the second largest consumer of energy after the refrigerator, it seems like a no-brainer to get one that's as energy-efficient as possible. But do these high-efficiency models actually exist? Find out on the next page.

 

Do high-efficiency dryers exist?

High-efficiency dryers don't actually exist yet, at least not in American appliance stores. The fact of the matter is that all dryers on the U.S. market today use about the same amount of energy. Energy Star doesn't even rate clothes dryers for this reason. And Energy Star won't even consider rating dryers until a cost-effective model that is at least 20 percent more efficient than standard models is available [source: Taddonio].

So what's with those alluring high-efficiency washer/dryer sets being sold by appliance companies like GE, Maytag, Kenmore and Whirlpool? If you look closely, you'll find that it's the washer that earns the high-efficiency rating. The dryer is just riding on the washer's coattails. The term "high-efficiency washer and dryer" is a marketing tactic that leads us to believe that both appliances are energy-efficient when, in fact, they aren't. Yes, the dryers have some energy-saving functions (more about these on the next page), but they are not using fewer kWh to dry the same amount of clothes.

There are, however, a number of new dryer models in development that aim to meet or exceed the Energy Star requirements. Some of these models, such as the heat pump dryer, are already being sold in Europe and are proving to be twice as efficient as standard dryers [source: Nipkow].

The reason that these dryers are not being sold in the U.S. may be that they cost quite a bit more (about $300 more) than regular dryers. Since energy is more expensive in Europe, it's easier for consumers there to justify spending the extra cash on an energy-efficient dryer. The European dryer will pay for itself with its energy savings faster than it would in the U.S. [Source: Taddonio]. Heat pump dryers currently on the market also take twice as long to dry a load of laundry, definitely a disadvantage over standard dryers. Though this longer drying time has been resolved in prototype models being tested for the U.S. market, a consumer survey found that U.S. consumers still wouldn't consider buying the high-efficiency dryers. The reason? They were too skeptical of the 50 to 60 percent increase in energy efficiency to justify spending the extra money [source: Lowe].

Nevertheless, heat pump dryers may be available in the U.S. soon. And research is currently being done into microwave technology that would dry your clothes the same way it heats your food, but they haven't ironed out all the wrinkles in that technology yet.

Energy Efficient Functions on Dryers

Currently, the only way for Americans to dry their clothes in an energy-efficient way is to string up a clothesline and use solar power. However, while line-drying saves energy, it adds some hassles, including extra time spent hanging clothes and waiting for them to dry. And of course, there's the unpredictability of the weather on laundry day to consider. Still, the "right-to-dry" movement, in which residents are fighting homeowners' associations for the right to hang clothes outside to dry, is gaining momentum across the country. Though you may not be willing to go that far, you can still save some energy when drying your clothes.

If you have an older dryer, it probably uses timed settings to dry a load of laundry. If you set the timer for 40 minutes and your clothes actually dry in 30 minutes, then you've used an extra 10 minutes of energy. Not only that, but you've over-dried your clothes. This translates to extra wear-and-tear on the clothes and generates that pesky static electricity that makes your skirt ride up your legs when you walk. Newer dryers attempt to solve the problem of over-drying in two ways:

  • Temperature sensor: Uses the temperature of the dryer exhaust air to estimate when clothes are dry and automatically shuts off the dryer
  • Moisture sensor: Shuts the dryer off when the humidity of exhaust air indicates that the clothes are dry

Either of these technologies will save energy, but the moisture sensor is more accurate, with energy savings of about 15 percent, compared to 10 percent for the temperature sensor [source: Flex Your Power].

Another way to help your dryer work more efficiently is by using a faster or extended spin cycle on the washer. Most of the newer washers have either faster spin speeds or several spin settings. Spinning the clothes faster or longer removes more water so that the dryer doesn't have to work as hard to dry them.

The choice of gas or electric will most likely depend on what kind of hook-up you have in your laundry room. In any case, gas dryers cost more up front than electric dryers, but cost less to operate over the years, so in the long run they may cost you less [source: California Energy Commission]. This handy calculator can help you estimate whether it's worth it to replace your old dryer, and whether it would benefit you to make the move to a gas-powered appliance.

Check out the links on the next page for more tips on dryers, laundry and energy efficiency.

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More Great Links

Sources

  • American Council for an Energy-Efficient Economy (ACEEE). "Major Home Appliance Efficiency Gains to Deliver Huge National Energy and Water Savings and Help to Jump Start the Smart Grid." Aug. 3, 2010. (9/7/2010) http://www.aceee.org/press/2010/08/major-home-appliance-efficiency-gains-deliver-huge-natio
  • American Council for an Energy-Efficient Economy. "Laundry." June 2010. (9/7/2010) http://www.aceee.org/node/3072
  • Bansal, P.K., Braun, J.E., Groll, E.A. "Improving the energy efficiency of conventional tumbler clothes drying systems." International Journal of Energy Research. Vol. 25. 1315-1332. 2001.
  • Bansal, P., Islam, S., Sharma, K. "A novel design of a household clothes tumbler dryer." Applied Thermal Engineering. Vol. 30. 277-285. 2010.
  • California Energy Commission, Consumer Energy Center. 2010. (9/7/10) http://www.consumerenergycenter.org/home/appliances/dryers.html
  • Consumer Reports Home & Garden Blog. 6/21/2010. (9/7/2010) http://blogs.consumerreports.org/home/2010/06/review-of-clothers-dryers-save-energy-when-drying-clothes-clotheslines-moisture-sensor-best-dryers-.html
  • Eastment, M. and Hendron, R. "Method for Evaluating Energy Use of Dishwashers, Clothes Washers, and Clothes Dryers." National Renewable Energy Laboratory Conference Paper. August 2006.
  • Energy Star. "What About Clothes Dryers?" (9/7/2010) http://www.energystar.gov/index.cfm?c=clotheswash.pr_clothes_dryers
  • Federal Trade Commission. "Energy Guidance: Appliance Shopping With the EnergyGuide Label." April 2008. (9/17/2010) http://www.ftc.gov/bcp/edu/pubs/consumer/homes/rea14.shtm
  • Flex Your Power. "Clothes Dryers." 2010. (9/7/2010). http://www.fypower.org/res/tools/products_results.html?id=100144
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  • Ng, Ah Bing and Deng, Shiming. "A new termination control method for a clothes drying process in a clothes dryer." Applied Energy. Vol. 85. 818-829. 2008.
  • Nipkow, J and Bush, E. "Promotion of energy-efficient heat pump dryers." Energy Efficiency in Domestic Appliances and Lighting (EEDAL) Conference. 2006.
  • Taddonio, Kristen. Analyst/Manager of Energy Star Appliances. E-mail correspondence. 9/16/2010.
  • U.S. Department of Energy, Energy Efficiency and Renewable Energy. "Laundry." 1/22/2009. (9/7/2010) http://www1.eere.energy.gov/consumer/tips/laundry.html