Research On Hygrothermal Characteristics And Optimal Design Of Civil Building Envelopes

The civil buildings are aimed to provide residents with a safe, healthy and comfortable indoor environment. Building envelopes separate indoor and outdoor space and have an important impact on building energy consumption and maintaining a good indoor environment. Coupled heat and moisture transfer has a strong influence on the hygrothermal performance of building envelopes, building’s overall energy consumption and indoor environment. The middle and lower reaches of the Yangtze River is a typical hot summer and cold winter region with a long period of high humidity climate conditions. Moisture transfer in the envelopes and large changes in outdoor temperature coupled with each other, which is a prominent feature in heat and mass transfer process in the building envelope in this region. Coupled heat and moisture transfer is an important factor of affecting the building envelope’s hygrothermal performance and building energy consumption and indoor air quality. Since building envelope materials are porous media, the calculation of the porous medium’s heat and moisture transfer mechanism analysis is very complex, the architects usually relies on the experience in the design of the building envelope, thus leading to many unreasonable designs.In this paper, a critical literature review on previous researches on heat and moisture transfer in building envelopes, the impact of the heat and moisture transfer on the overall performance of the building (including the thermal performance of the building envelope and building energy consumption and indoor air quality) have been carried out. Experimental tests of four building envelope materials have been conducted at the Center for Sustainable Building Research in Nanjing University. The classic climate chamber method was adopted in the research. The experimental results have been compared with the simulation results from CHAMPS-BES to verify each other, the accuracy of the experiment and simulation were determined, then using of the laboratory equipment and CHAMPS software provides a convenient for the future research on heat and moisture characteristics of the other new building materials. Case study of two different walls of a building in Nanjing University campus has been carried out by using CHAMPS-BES. According to the above studies, to the thesis finally investigate the optimization design of material selection and the form of wall structure in civil buildings envelopes.