Abstract
Experiments on ventilation efficiency were performed using a test house in summer. In this system, outdoor air supplied from the crawl space goes through inner space of the walls to the attic space. The air of inner space of the walls is supplied to room through air inlets between inner space of the walls and rooms. The parameter of experiments is number of the air inlets. As the result of experiments by step-down and step-up method, it was found that the outdoor air reached to the rooms as expected and the air inlet is useful for supplying the air.