Thermal performance of cavity masonry walls and thermal design investigation in Western China

A cavity masonry wall (CMW) is a high performance envelope used in Western China for integrating thermal insulation and heat storage. However, a suitable method has not been developed for designing CMWs, especially the thermal resistance of the closed air cavity. In the present study, the effects of the structure parameters were analyzed and the thermal resistance of the closed air cavity was determined. A mathematical model of CMWs was established and validated based on experiments. This model was used to analyze the effects of the wall emissivity, thickness of the closed air cavity, and the thicknesses of the insulation material layer and thermal mass layer in CMWs. Furthermore, the thermal resistance of the closed air cavity was investigated. Finally, the energy performance of buildings with CMWs was analyzed. The results showed that the wall emissivity of the closed air cavity and thickness of the insulation material layer had significant effects on the intensity of heating and cooling, and fluctuations in the internal surface temperature. The thickness of the thermal mass layer mainly affected the fluctuation in the internal surface temperature, and the thickness (concrete) should exceed 0.15 m. The thickness of the closed air cavity had little effect but an optimal thickness was identified. The thermal resistance of the closed air cavity was also affected by the wall temperature difference depending on the outdoor climate type, and it had a highly significant impact on the heating load for buildings with CMWs.