alt Hacker NewsDoesn't AC mean air? Air conditioning? There's no air involved here - it's basically antifreeze pumped through the floors/ceilings. The heat exchanger is an enclosed chamber where warm molecules exchange across into a cool chamber, in summer it's warm molecules from the brine that was in our floors/ceilings and the cool air is the 11c brine that runs through pipes in the ground. across a fin/radiator. It's all completely enclosed. The only "AC" is in the enclosed heat exchanger where warm and cold air molecules move between chambers.
Oh I should mention though, there is a compressor that compresses a volatile gas that is the carrier of the heat from the warm to the cold chambers. But it's so efficient that it's pretty much free to cool kostenlos/free cooling) using ground temp (11c here). Heating in winter does cost something because we like to be warmer than 11c.