Study on Air Conditioning Systems applied Natural Porous Materials for Passive Control of Temperature and Humidity and adsorption of VOC

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Siliceous shale from the Wakkanai formation shows quite high performance of humidity control compared to another natural porous materials from cost effectiveness point of view. The Wakkanai siliceous shale can be adapted for building materials in particular since it shows the high capacity in both adsorption and desorption even at normal temperature and humidity conditions.The effect of humidity control is demonstrated in a testing room with a floor area of 7.5m^2. Gypsum boards or plaster painting, in which the Wakkanai siliceous shale is mixed in 1.92kg/m^2 or 0.68kg/m^2 respectively, can be applied for one side of inner walls of 23.2m^2. Both the wall conditions show more stabilized humidity than another condition with normal gypsum boards in some experiments in which humidification and dehumidification are repeated every six hours.Numerical simulation predicts the reduction of mold generation in the humid rainy season by use of such building materials with humidity control. Risk rate of mold generation can be reduced more than 90% in one calculation with the weather data of Tokyo.Adsorption of VOC gases can be observed in rocks and tiles with the Wakkanai siliceous shale by measurements with a chamber of 20 L in a closed system at constant temperature and humidity around 25℃ and 50%, respectively. The characteristics of breakthrough are also measured with ammonia gas in 25ppm by using an adsorption glass column in an open system. One result shows that 2.11 mg/g of supplied ammonia gas is adsorbed in rocks of the Wakkanai siliceous shale in the column at a removal rate of 20%, which is equivalent to 30 times larger amount of adsorption than that in activated carbon pellets as a standard adsorption material.