low humidity prevention strategy

As highly insulated and airtight houses have built popularly, the problem which indoor air becomes lowhumidity in winter, is paid attention. The problem is caused by rise of heating level and increase ofventilation amount by mechanical ventilating equipments, etc.1)Then, to clarify the actual condition of indoor low humidity in winter, we monitored the actual humidityenvironment in 29 occupied houses in the Tohoku region and Niigata, Japan, from 2001 to 2006. As theresult, it is found that the indoor low humidity in winter is a common problem regardless of the housecondition.