We are told that, during the winter months, letting the house cool down at night saves energy. But, and I may be wrong here, letting the house cool down for a couple of hours while I am out running errands, then heating it back up strikes me as actually using more energy than if I had just held the temp steady. Does anyone have any thoughts on this?
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Favorite Answer
Think it this way. Change in temperature does not cost money. Because you will anyways heat house to comfortable level, we can look instead energy consumption the amount of energy lost in every moment. Every time you drop house temperature the amount of heat/energy lost through walls will decrease because, well there is less heat to leak.
If you decide to freeze your house(don't do it) and after that heat it fast consumption of heating will be really huge momentarily but total energy consumed will be always lower than if house were heated all of the time.
Only obvious exception is if you open window to cool house down.