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that is a ground-source heat pump as the heat energy is mostly from ambient solar. But yes very common and I used to have one in my home before I moved away. It cost practically nothing to keep the house at t-shirt temperature during -25c cold weather snaps.

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No it's not. The bore-hole is lined with a outer steel pipe until the drill hits bedrock, keeping it very much insulated from the ground. And the upper-most part of the energy-well that's lined is considered inactive, and is not counted in the "150 m deep energy well".

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