The current of air-tightness and ventilation system in houses of Japan

摘要

In recent years, the insulation and air-tightness levels of newly constructed houses in Japan have been improved for purpose of energy saving. However, a reduced design of air permeability (i.e. a high level of air-tightness) will provide insufficient air through infiltration resulting in a significant and negative impact on a social problem of sick house syndrome. The Japanese Building Standard has been revised to reduce the concentration of Formaldehyde which is considered to be one of the main causes of sick house syndrome. This Standard provides guidance concerning the specific preferences, for instance, ventilation systems should be placed in the buildings and the usage extent of interior material should be restricted depending upon individual conditions of emission volume of Formaldehyde. As a result, the sick house problem seems to be declining gradually. However, this problem has not yet been solved, and health disorder caused by chemical substances, besides Formaldehyde, mould and fungus has become a big problem recently.In this paper, the method of measurement, the actual circumstances, certification and problems of air-tightness of houses in Japan, which are deeply concerned with the problems mentioned above, is firstly stated. Secondly, the current of ventilation system, contents of Japanese Building Standard, results of measurement on ventilation rate and problems of ventilation systems, necessity of commissioning procedure for ventilation system, and subjects in the future will be described.