5.6: Clothes Dryers

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A clothes dryer dries wet clothes in a rotating drum through which hot air is circulated.

The hot air removes the residual moisture from the clothes.
The humid air from the dryer is vented out of the house.
The drum is rotated with the help of a motor at relatively slow speeds to create a tumbling effect.

Clothes dryers can be of two types: electric and gas.

In an electric dryer, electrical energy is used for both the motor to rotate the drum and heating the air.
In a gas dryer, the motor requires electrical energy but the air is heated by natural gas.

Energy Efficiency of Dryers

Dryers work by heating and aerating clothes. The efficiency of clothes dryer is measured by a term called the Energy Factor. It is similar to the miles per gallon for a car, but in this case the measure is pounds of clothing per kilowatt-hour of electricity.

The minimum Energy Factor rating for a standard capacity electric dryer is 3.01. For gas dryers the minimum energy factor is 2.67. The rating for gas dryers is provided in kilowatt-hours though the primary source of fuel is natural gas.

Unlike most other types of appliances, energy consumption does not vary significantly among comparable models of clothes dryers. Clothes dryers are NOT required to display EnergyGuide labels.

Here are some things you can do to minimize the environmental impact of your clothes dryer.

Locate your dryer in a heated space. Putting it in a cold or damp basement will make the dryer work harder and less efficiently.
Make sure your dryer is vented properly. If you vent the exhaust outside, use the straightest and shortest metal duct available. Flexible vinyl duct isn't recommended because it restricts the airflow, can be crushed, and may not withstand high temperatures from the dryer.
Check the outside dryer exhaust vent periodically. If it doesn't close tightly, replace it with one that does in order to keep the outside air from leaking in. This will reduce heating and cooling bills.
Clean the lint filter in the dryer after every load in order to improve air circulation and reduce risk of fire. Regularly clean the lint from vent hoods.
Dry only full loads, as small loads are less economical; but do not overload the dryer.
When drying, separate your clothes and dry similar types of clothes together. Lightweight synthetics, for example, dry much more quickly than bath towels and natural fiber clothes.
Dry two or more loads in a row, taking advantage of the dryer's retained heat.
Use the cool-down cycle (permanent press cycle) to allow the clothes to finish drying with the residual heat in the dryer.
In good weather, hang clothes dry outside. This is the ultimate energy saver for clothes drying.