Indoor air quality is of increasing concern and the terms “sick building syndrome” or “sick house syndrome” are now creeping into our everyday vocabulary. This is because moderno?cebuildingsandhousesareconstructedfromthe viewpoint of energy conservation with a high degree of air tightness and thermal insulation and with new construction materials, but this occasionally leads to insu?cient consideration for the ventilation of room air [1,2]. To develop methods of coping with this problem of indoor air pollution, a wide range of studies have been performed on emission and di&usion of contaminants from new construction materials [3,4]. The e&ects of indoor air contaminants on health have also been reported [5]. Furthermore, studies of indoor
∗Corresponding author. Tel.: +81-3-5452-6431; fax: +81-3-54526432. E-mail address: kato@iis.u-tokyo.ac.jp (S. Kato).
air quality employing computational 8uid dynamics (CFD) arewidespread,becauseCFDiscapableofprovidingprecise information on factors including the distribution of 8ow and concentration. Several indexes of ventilation e&ectiveness have been proposed and examined with the aid of CFD [6–8]. Recently, air quality in the region of inhalation by human occupants has attracted interest [9–11]. In this paper, we 4rst examine the e&ectiveness of the exhaust opening by introducing a new index, IECV, showing the effectiveness of contaminant ventilation, using the product of the concentration of the contaminants in indoor air and the portion of the air vented from an exhaust opening. Using IECV and other factors, the characteristics of contaminant ventilation from an exhaust opening were examined in a simpli4ed two-dimensional room. We then applied these concepts to the more realistic case of an inhaling human occupant employing three-dimensional CFD, assuming the human mouth at inhalation to be an exhaust opening. Corresponding to the index IECV, we de4ned another new index, IECI, showing the effects of contaminant inhalation