I don’t get it. How is cold, even freezing air turned into heat? How is it less energy consuming than other heating systems?
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The conceptual problem with understanding heat pumps is that what we think of as cold isn’t, physically speaking, all that cold. On the “true” temperature scale – where 0 is “the coldest anything can be” – water freezes at 273 Kelvin and human body temperature is 320 K, i.e. only 17% hotter (one degree Kelvin is the same temperature difference as one degree Celcius, they just have zero in a different place). Thus, there is still a lot of heat in air/water/earth/rock at freezing temperatures, some of which can be extracted (reducing the temperature to, say, 5 degrees below freezing) and dumped into the space you want to heat up. This heat is “cheap” – you haven’t had to make it all from burning something or running electricity through a resistor, you’ve just had to scoop it up and put it somewhere else. It does take some energy to move heat from a colder place to a hotter place, but not very much if the colder place isn’t all that much colder than the hotter place. And since, in the absolute scale, a frosty morning isn’t actually much colder than ideal room temperature (something like 10%), you can move something like 3 units of heat energy for every one unit of electrical energy you use up in moving it.
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