It ' s just a bathtub . If I remember right , it ' s the bathtub , then you have to take it to reese ' s husband , cyrus . <| sep |> Heating and cooling anything is where a house like the ones in America will use the most energy . Heating water , heating and cooling the house , heating food in the oven , drying clothes . Practically everything else in a house can run on a lot less power lights , TV , computers , etc . Any heat these things create is considered waste . Incidentally , waste is simply whatever you ' re not trying to achieve , efficiency is whatever you are trying to achieve . ExampleOldfashioned incandescent light bulbs generate a lot of heat and use much more electricity than fluorescents or LEDs . So incandescents are considered wasteful , less efficient . BUT suppose you want to hatch chicken eggs in an incubator and keep the baby chicks warm . Incubators have generally used light bulbs for this purpose , for many decades . For this use , you WANT the ' waste ' heat , and putting an LED bulb in an incubator would be less efficient for that purpose indeed , an LED will generate so little ' waste ' heat that it ' s utterly useless for an incubator . This wasteefficiency principle applies to many things in life . If we say that one metric is highly efficient , some other metric must be less efficient . But often we don ' t care about the second metric , so that ' s the ' waste ' we want to eliminate . If a factory owner could get so much efficiency out of just one employee that ten thousand others could be permanently laid off , the factory owner could maximize profit by ' getting rid of the dead wood . ' Very efficient . But in the view of ten thousand jobless workers , a factory owner pocketing the equivalent of ten thousand salaries is , shall we say , not efficient for their purposes .