The current of air-tightness and ventilation systemin houses of Japan

In recent years, the insulation and air-tightnesslevels of newly constructed houses in Japanhave been improved for purpose of energysaving. However, a reduced design of airpermeability (i.e. a high level of air-tightness)will provide insufficient air through infiltrationresulting in a significant and negative impact ona social problem of sick house syndrome. TheJapanese Building Standard has been revised toreduce the concentration of Formaldehydewhich is considered to be one of the maincauses of sick house syndrome. This Standardprovides guidance concerning the specificpreferences, for instance, ventilation systemsshould be placed in the buildings and the usageextent of interior material should be restricteddepending upon individual conditions ofemission volume of Formaldehyde. As a result,the sick house problem seems to be declininggradually. However, this problem has not yetbeen solved, and health disorder caused bychemical substances, besides Formaldehyde,mould and fungus has become a big problemrecently.In this paper, the method of measurement, theactual circumstances, certification and problemsof air-tightness of houses in Japan, which aredeeply concerned with the problems mentionedabove, is firstly stated. Secondly, the current ofventilation system, contents of JapaneseBuilding Standard, results of measurement onventilation rate and problems of ventilationsystems, necessity of commissioning procedurefor ventilation system, and subjects in the futurewill be described.