How do heat pumps work and why are the energy efficient?
Edit: the question is sufficiently answered. Thanks guys!
In: 50
Think lf heat as how much energy there is in one place. Even if it’s cold outside there is still energy in the air, only less than inside. So the idea is to take some of that less dense energy, make it more energy dense than inside air(by increasing the pressure) and letting the now more energy dense air increase the temperature inside. If the energy spent to increase the pressure leads to more heat being produced than just burning gas, the efficiency can be said to be over 100%.
Non ELI-5:
There are fundamental physical problems with creating an efficient heat pump if the difference in temperature is too high (look up Carnot Heat Pump), therefore in cold climates(mostly scandinavia afaik) what is called a geothermal heat pump is often used. Instead of using outside air a hole is drilled into the ground. Once you get into bedrock/deep enough the temperature doesn’t fluctuate much (often assumed 10c/50f) so the temperature difference is qyite small and they retain high efficiencies regardless of outside temperatures. Also fun fact, a refrigerator/freezer is essentially a heat pump run in reverse.
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