Japanese modern houses become highly airtight and thermally insulated, because of saving energy. As a result, problems related to humidity of indoor air have been increased, for example, excessive dew formation etc. To solve these problems, we have developed a new humidity controlling material using porous soil "allophane". It was found that the moisture adsorption property of this material was higher than that of wood in laboratory test. Effects of this material in the living space were examined by measuring humidity and the amount of dew condensation before and after applying this material in practical houses. It was cleared that this building material could decrease humidity change and the amount of dew condensation in the living space.
