Simulation of thermal and humid environment of rural residence envelope inner surface during the plum rains season in Changsha China

Abstract

The Plum Rains Season (PRS) has the typical characteristics of outdoor air temperature dramatic changes and high air humidity in the hot summer and cold winter region in China. Even if the indoor heat source and moisture production is constant, when the outdoor air temperature rises rapidly during high air humidity PRS, the building envelope temperature heats up much more slower than the indoor air temperature and therefore the wall surface temperature is lower than the indoor air dewpoint which leads to condensation phenomenon, resulting in deterioration of insulation performance, mouldy walls, deterioration of indoor air quality. At present, there is a lack of research on the factors affecting condensation in rural residence during PRS. This paper evaluates the impact of occupants’ habit of window opening modes and building construction parameters on the building envelope surface condensation in Changsha during PRS. Using Designer'Simulation Toolkit (DeST) simulated and analysed the impact of key parameters such as window-to-wall ratio, exterior wall reflectivity, window opening mode (open/close), and external wall insulation on the building indoor thermal and humid environment. The condensation risk X is proposed to evaluate the condensation possibility on the building envelope's inner surface. The results show that from the perspective of anti-condensation: The rural residential building in Changsha should balance the window-wall ratio against better natural lighting; Keeping windows closed during PRS can effectively alleviate the condensation problem while the insulation in the external wall layer could aggravate the condensation.