No matter where you live, you can use the stable temperatures of the earth to condition building spaces. In winter, the ground is warmer than the air, so it can be used to heat a house. In summer that relationship flips and the cool ground can act like A/C.
A heat pump works somewhat counterintuitively, by extracting heat from a cool space (the earth) and dumping it in a warm space (your house), much like a refrigerator draws heat out of its cool interior and emits it into your kitchen. The pump transfers heat using a nontoxic fluid with a low boiling point.
This fluid runs through an underground pipe system, absorbing warmth from the earth and reaching a boil rapidly.
Evaporated gas (equivalent of steam) is then compressed ; the high pressure causes the gas to condense, releasing its heat to warm the house and heating water for domestic use and the outdoor pool.
The low-pressure fluid is then returned underground to pick up more heat, carry it into the house, and deliver it again.
The process can be run in reverse in the summer, absorbing indoor heat into the fluid and depositing it underground.
Solar panels provide supplementary energy to heat the boiler and pool.
A heat pump actually delivers more thermal energy than it uses. Conventional heaters can’t provide more energy than what’s contained in the fuel that’s burned. But heat pumps use a small amount of electricity to move a large amount of thermal energy around. Most of the heat comes from the earth, and the only input required is the electricity to run the compressor.
While conventional heaters have efficiencies of around 80 percent, heat pumps can have efficiencies greater than 100 percent, typically around 300 to 400 percent.