PURPOSE: To provide a heat exchanging device capable of enhancing thermal efficiency at the time of using energy in the natural world in its original condition.

CONSTITUTION: The temp. exchanging device 10 utilizing heat of diffuse sky radiation is provided with sky planes 5, 6a and 6b composed of the material 8, by which long wave is transmitted and short wave is not transmitted and fluid such as air is heated or cooled by materials 8 and 9. In this way, the production of the temp. exchanging device is realized, which is simple in structure, inexpensive to install the required electric equipment, operative at low costs and easy to maintain. Due to utilization of the natural energy to obtain heat, moreover, this device produces no harmful effect on environment and can regulate temp. more efficiently as compared with other temp. regulators utilizing natural energy.