They must be using a heat pump (from the ground source) for the pool, otherwise yes it would be way too cold.
I have often thought about the idea of using heat from refrigerators but I think that would be more trouble than it's worth for small domestic fridges. But definitely if they have this ground source system, they use that as a shared heat reservoir that the heat pumps air conditioning apartments in summer reject heat into and the heat pumps heating hot water draw from.
I have often thought about the idea of using heat from refrigerators but I think that would be more trouble than it's worth for small domestic fridges. But definitely if they have this ground source system, they use that as a shared heat reservoir that the heat pumps air conditioning apartments in summer reject heat into and the heat pumps heating hot water draw from.