Papers by Author: Shui Yu

Abstract: The research of coupled heat and moisture transfer is a complex process, which is the fundamental of decreasing building energy consumption; improving IAQ and increasing the durability of building envelop. CHAMPS-BES software is an outcome of a joint effort between Building Energy and Environmental Systems Laboratory (BEESL) and Institute for Building Climatology (IBK). This software is used for analysis and prediction of hygrothermal performance of building enclosures; impact of outdoor climate and pollution on indoor environment; impact of VOC emissions from building materials and indoor furnishings on indoor air quality. This paper introduces the basic mathematic and physic model, boundary condition, climate condition etc, and analyzes the coupled heat and moisture transfer through common structure of building envelop in Shanghai. According to simulation results, main materials of the wall in ITIS have to endure larger range of temperature than ETIS that leads to the life of materials shorter. Capillary condensation occurs on inside surface of the wall easily when RH is larger than 70% and the minimum pore size of finish layer is around 5×10-9m avoiding capillary condensation and mold growth

Abstract: The research on water vapor transmission (WVT) has an important function on analyzing moisture transport through building materials. According to ASTM Standards, there are two traditional methods (Dry cup and Wet cup) to test WVT of porous materials for practical application, without considering the influence of relative humidity and air flow. In this paper, multilayer method is used to test WVT of porous materials, without the influence of air flow on the whole testing process. Multilayer test method is the new way and there is little experience on how to conduct the whole process, how to obtain the accurate data and make the whole process reasonable is the big issue. Through several cases are worked on and analyzed, then renew desiccant every two hour which is depending on the type of porous materials, is the best way to make the whole testing system reaching to steady state for special building materials. At last, this paper shows that the new way is more reasonable and has higher accuracy than traditional method to get WVT.

Abstract: The research on water vapor isothermal sorption of porous building materials have an important function on controlling and solving hygrothermal problems, such as durability, thermal insulation, mold growth and indoor air quality, when building materials are in hygrothermal environment, especially in the high humidity environment. The isothermal sorption is used to describe the maximum moisture sorption capacity, if moisture content exceeds the limitation, probably there will be liquid water appearance, which lead to the risk of mold growth, decreasing durability and increasing thermal conductivity, and so on. The classic testing method of isothermal sorption could be found in ASTM Standards C 1498-01. In this paper, the eco-stucco, eco-fiber batt and eco-fiber board is tested using traditional method. Meanwhile, pore size distribution and capillary condensation is analyzed which is challenge for the design basis of hygrothermal character for the building envelope.