To effectively use solar heat and underground heat to adjust residence room temperature.

A concrete tank 24 is embedded into the ground, and a heat exchange pipe 26 is arranged within the concrete tank 24. Inside of the concrete tank 24 is filled with rain water, underground water or running water. In summer, by using storage water 27 within the concrete tank 24 cooled by underground heat, air supply from a total heat exchange type ventilation fan 5 is made to flow via the heat exchange pipe 26 within the concrete tank 24 to send weak cold air to each room, so as to achieve efficient weak cold air operation. In winter, since low temperature hot water within the concrete tank 24 heated by underground heat is circulated in a solar heat water heater 2, the low temperature hot water in the concrete tank 24 is further warmed, and air supply from the total heat exchange type ventilation fan 5 is warmed via the heat exchange pipe 26 within the concrete tank 24, so as to send the warm air to each room.