In a heat pump tumble dryer, the heat pump is used to extract moisture from the laundry and then release it outside the dryer, allowing the clothes to dry. Heat pump tumble dryers are more energy-efficient than traditional tumble dryers because they use less electricity to operate the heat pump, rather than generating heat directly with heating elements. They also tend to be gentler on clothes because they operate at lower temperatures, which can help to reduce shrinking and damage to delicate fabrics.