Basic Theoretical Study And Experiment On Humidity Controlling Materials Subjected To Building Envelope

People spend 80% of lifetime indoor. Indoor thermal and humidity environment and thermal and humidity condition of building envelope have always been scholars' great concern. Applying humidity controlling materials on the inner surface of building envelope, as a modern, energy-saving and environmental friendly method of controlling humidity, can effectively prevent building envelope from dewing. It can also control indoor humidity.This paper is mainly about the application of humidity controlling materials on building envelope. Heat and moisture transfer at building envelope, humidity adsorption and desorption at inner surface is studied. Adsorption theory is used in explaining the humidity adsorption and desorption principles, equilibrium moisture adsorption isotherms and adsorption hysteresis of humidity adjusting material.Since it is necessary to study the humidity-controlling capacity of humidity controlling materials quantitatively, this paper experimentally researched moisture adsorption process of 100 meshes bamboo charcoal, charcoal and diatomite, and relating data of experimental standard of humidity absorption properties are used for reference. Result of experiments shows that at certain temperature and humidity, the humidity adsorption speed of 100 meshes bamboo charcoal and charcoal has linear relation with the humidity. It is proved that the humidity absorption process of these two materials has exponential attenuation property. The function of 100 meshes bamboo charcoal and charcoal's humidity content changing with time during dynamic humidity adsorption process is achieved. Software is used in simulation and calculation of bamboo charcoal and charcoal's equilibrium humidity content data. Thus humidity adsorption equilibrium humidity content curve equation and characteristic index of humidity controlling κ at 30℃ is achieved. Moreover, absorption experiment of bamboo charcoal at enclosed space shows that the characteristic index of humidity controlling of bamboo charcoal at enclosed space is mainly determined by its quantity. Surface area and thickness is of little effect.