PURPOSE: To cool a building effectively during daytime, by forming a ventilating layer and a hollow space in the wall of the building in the manner that the former is located on the outside and the latter is located on the inside, and accumulating cold by circulating air cooled in the ventilating layer in the night through a space under the floor of the building, hollow spaces in the wall and a roof space.

CONSTITUTION: Ventilating layers S1, S2 are formed along the outer wall of a building, and the upper portions of these layers S1, S2 are communicated to a space 11 in the ceiling, while the lower portions are communicated via ducts 7, 8 to a control box 1 installed in a space 12 under the floor. The control box 1 includes check valves 4 which permit air only to flow from the duct 7 or 8 to the box 1 and an upper ventilating port 16 with a damper 3 actuated by wires 5,6. Further, hollow spaces 9 are formed in the wall to communicate the space 14 in the ceiling and the space 12 under the floor with each other. With such an arrangement, it is enabled to carry air in the ventilating layers S1, S2, cooled in the night, in the downward direction as shown by arrows in the drawing in summer, to accumulate cold by circulating the cool air from the space 12 under the floor to the roof space 11 in the ceiling via the hollow spaces 9 in the wall, and to use the cool air for cooling of the building during daytime.