Why do economy programs or options take much longer?

People are often very puzzled by how using an eco wash program, or selecting economy options on their washing machine, dishwasher or tumble dryer causes it to take a lot longer to complete the cycle. It seems completely counter intuitive. I’ve been asked the following question many times -

Q: “How is it that the ‘Economy’ cycles take twice as long as the regular wash? How is that economical? I would have thought that would use more electricity.

Here’s the answer: Heating up the water in a washing machine or dishwasher, or the air in a tumble dryer is what really costs money. When the heater is turned off they hardly use any electricity. For example, a washing machine running with the heater on for just 15 minutes would use considerably more electricity than just washing the clothes with the heater off for hours.

The economy wash programs need to use less electricity to save money, so they use lower temperatures, or in the case of some dryers they use a heat pump to recirculate some of the warm air. And because that isn’t as efficient they have to compensate by physically washing or tumble drying for longer. So although the economy washes and settings take longer, they use less electricity.