Dryers work by heating and aerating clothes.
The efficiency of a clothes dryer is measured by a term called the energy
factor. It is somewhat 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 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.