To provide an air conditioning system of a novel structure carrying out the cooling of the summer season and the heating of the winter season through ground heat, solar heat, or wind power being natural energy sources without using fossil fuel like a conventional air conditioner in regard to air conditioning of a room.

The air conditioning system is characterized by that two heat storage tank type heat exchangers in different structures are provided side by side underground, and by taking in outside air and serially passing it through the heat exchangers, cold air in the summer or warm air in the winter is supplied into the room. Supply of the cold air and the warm air is effected by a combination of a first heat storage tank annually leveling the temperature of passing air and a second heat storage tank further amplifying cooling-heating. In the air conditioning system, ground heat is used as a cold/heat source in the first heat storage tank, and natural energy such as solar heat or wind power energy is used in the second heat storage tank, and natural raw material such as water or air is used as a heat transfer medium.