To provide a ventilation air conditioning system friendly to the environment and the human body, utilizing subterranean heat, and to provide a system and device carrying out ventilation, air conditioning, and purification by outside air and heat storage liquid utilizing heat of a subterranean constant heat layer.

To efficiently carry out reception and dissipation of heat of gas, the outside air is blown into the heat storage liquid in a rotated/agitated heat storage tank to carry out heat exchange with the outside air and purification of dust or the like. For reheating and re-cooling, air is passed through a heat exchange duct provided with a heat exchange coil unit with a filler, and it is sent to each room of a building to carry out air conditioning along with ventilation. In regard to subterranean heat utilized therefor, it is investigated that a temperature zone close to constant heat can be obtained in a layer at a comparatively shallow underground depth of about 2-3 m right below the building, and by burying the heat storage tank and a heat storage liquid piping for heat exchange in the layer, subterranean heat is utilized in a short period time with inexpensive construction costs by easy construction using common machinery. Air is humidified/dehumidified, cleaned, heated/cooled, and sent by a purification heat exchange apparatus system utilizing natural subterranean energy.