A ventilation method to attain an improved indoor air quality under effective use of energy was examined in a small office type experimental room. The experiments were carried out using human subjects. This paper reports the possibilities of ventilation efficiency improvement and lessening of ventilation requirements when upward ventilation is applied, compared to downward ventilation. Upward ventilation leads the high ventilation efficiency because upward ventilation utilizes upward free convection caused by the metabolic heat around a human body. Therefore less ventilation requirement allows to realize a hygienic space with upward ventilation compared to traditional mixing ventilation.
