Let us consider the case of a room in winter. It has one opening at the bottom left where cold air enters at low speed and another opening at the top right from which the air heated by the human occupant is vented as shown in Fig. 7. In this study, there is a single occupant, and the three postures of standing, sitting and sleeping1 are examined in order to evaluate inhalation features according to posture as is shown in Table 2. The standing posture represents an occupant working at the center of an office and facing the air supply opening (Fig. 7(1)). The sleeping posture represents a human occupant lying on its back in the center of the room. To avoid direct influence of supply air flow on the region of inhalation, the feet of the occupant are facing the supply opening (Fig. 7(2)). Although breathing is an irregular phenomenon, it was assumed to be steady for the purpose of the study, because the amount of air exhaled from the mouth is too small to influence the indoor air flow.2 The amount of inhaled air was assumed to be at the mouth.3 The area of the mouth opening was assumed to be .