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How does design affect a dryer's energy efficiency?

Does the type of dryer you have effect how efficient it'll be? See more green living pictures.

When you're shopping for a new clothes dryer, it pays to know how it actually works. It pays even more to know how much money you can save depending on the type of dryer you choose.

Simply put, a clothes dryer tumbles and heats wet clothes. The dryer pulls in air, passes it over heating elements, and then sends it into the dryer drum. The tumbling action of the drum separates wet surfaces, allowing warm air to circulate around clothes and convert moisture to steam. A fan blows steam out of the dryer through the vent. The tumbling motion and air injection fluff clothing up, similar to the way a hand mixer whips air into egg whites to fluff them into meringue. That's why clothes dried in a dryer are so much softer than clothes dried on a line.

But clothes dryers are energy hogs. A typical dryer uses nearly 1,000 kilowatts of energy annually and costs around $85 per year to operate. Clothes dryers are all so similar in energy usage that the U.S. Department of Energy doesn't even rate them for the Energy Star program -- and some rated appliances only have to be 10 percent more efficient than standard models to qualify for the Energy Star label.

Some dryer features can boost efficiency, however. A moisture sensor turns the machine off when moisture drops below a certain level, saving energy (and your clothes) from drying too much. A cool-down feature helps, too. Near a cycle end, the dryer continues to tumble clothes, but without injecting heat. It completes the drying process using residual heat, which eventually dissipates and leaves your clothes cool for immediate folding.

One manufacturer, Fisher Paykel, builds a top-loading dryer. This machine can reverse tumbling direction, which supposedly promotes faster drying by keeping your clothes from balling up.

Regardless of your dryer's design or special features, there are several things you can do to save energy:

  • Make sure your washer spins as much water as possible out of clothes before putting them into the dryer.
  • Don't overload the dryer. Clothes need room to tumble, and air doesn't circulate well in a packed dryer.
  • If your dryer has different heat settings, use them. While towels may need high heat, most loads dry efficiently with medium or low heat.
  • Separate clothes by weight or fabric type into loads that need similar heat and drying time.
  • Clean the lint screen after each use. This improves efficiency and safety.
  • If you use dryer sheets, scrub the lint screen with a toothbrush each month to remove accumulated film that prevents air from circulating.
  • Make sure the vent hose isn't crimped or clogged.
  • Remove clothes as soon as the drying cycle ends so you won't need to turn it back on to re-fluff or de-wrinkle heaped-up clothes.
  • Pre-dry larger and heavier items on a clothes line, and then use the dryer to fluff and soften.

The most efficient dryer design is actually the simplest -- the clothes line. It uses free energy from the sun and wind. Of course, there are certain drawbacks. You'll run the risk of collecting airborne items such as pollen and bird droppings on your clothes. And many home owners' associations frown on such displays of energy conservation. If you can't dry your clothes naturally outdoors, you can use collapsible racks and frames for indoor air-drying.