The heat is probably stored in water by using a simple counter flow heat exchanger. So at night they are using the ‘cool’ ground water for cooling and during the day, they are using the ‘warm’ ground water for heating, probably involving a heat pump.
The heat is probably stored in water by using a simple counter flow heat exchanger. So at night they are using the ‘cool’ ground water for cooling and during the day, they are using the ‘warm’ ground water for heating, probably involving a heat pump.