Prediction of Wall and Indoor Hygrothermal Properties of Rammed Earth Folk House in Northwest Sichuan

Abstract

The climate crisis is one of the most important problems today. In the process of human building, the use of cement, steel, and other industrial materials in the process of building construction and recycling has brought a huge burden to the natural environment. Earth is one of the oldest building materials, its availability and insulation make it an excellent constructive solution in human history. Among several existing earth construction techniques, rammed earth is one of the most relevant. In this paper, a numerical model of the rammed earth folk house in Mianyang was established, and an experimental device was built to verify it. With the typical meteorological year data of Mianyang in northwest Sichuan, the heat and moisture transfer in rammed earth wall, as well as the indoor thermal and moisture environment were numerically simulated. The results show that the rammed earth wall weakens the temperature fluctuation of the inner surface of the wall and makes the peak temperature of the inner surface of the wall lag the outer surface. The relative humidity in the center of the rammed earth wall can be maintained at about 60%, both in winter and summer. The moisture absorption and desorption capacity of rammed earth walls without inner decorative materials is about three times that of gypsum board, and the use of a waterproof coating will render the rammed earth wall almost unable to adjust the indoor relative humidity. Additionally, the use of decorative materials will increase the fluctuation range of indoor relative humidity and the risk of mold breeding.