PURPOSE: To provide a cooling effect in a room in a summer season and a heating effect in a winter season by a method wherein a thermal insulation material, air ducts and air feeding fan are arranged.

CONSTITUTION: Air flow passages 6 and 6' are formed in a housing 1, an air feeding fan 12 is arranged at the uppermost part of a garret space 5 above the garret thermal insulation walls 10 and 10', a feeding of air from the air blowing fan 12 is connected to two air ducts 14 and 14' through change-over valves 13 and 13', an air blowing port 15 of one of the air ducts 14 is arranged out of the housing, the blowing port 15' of the other air duct 14' is arranged at a space below the floor 4 and further an electric damper 16 is arranged in the space below the floop 4 and at a communication window out of the housing. With this arrangement, in summer season, the hot air in the space 5 in the garret is taken out from the blowing port 15 by the blower fan 12 through a partiation valve 13 and in turn in winter season the hot air in the garret space 5 and the space below the floor is taken in by the blow fan 12, so that it is made possible to keep a proper temperature in both summer and winter seasons.