Effect of moisture on the thermal performance of exterior walls in the tropical islands of the South China Sea

Abstract

Accurate evaluation of the moisture effect on the thermal performance of building envelopes is essential to facilitate energy-saving building design in hot and humid climate areas. However, in extremely hot and humid climate areas, the coupled effect between the heat and moisture transfer is mostly neglected and a method to evaluate the moisture effect on the thermal performance has never been proposed. Thus, in this paper, a model is developed to simulate the coupled heat and moisture transfer inside an exterior wall subjected to extremely hot and humid climate. This model is validated using three benchmark tests and shows high accuracy. Based on the model, the effect of the moisture on the thermal performance of exterior walls in the tropical islands is firstly investigated quantitatively. The results show that moisture can substantially affect the thermal performance of an exterior wall. Neglecting the moisture effect, the total load is underestimated by 6.04–7.33%. Considering the moisture effect, the decrement factor is improved from 26.27–38.28 to 79.40–114.41 and the time lag is prolonged by 71–79 min. Finally, to clarify the spatiotemporal dynamic pattern of the moisture effect, a comparison between the four tropical islands and the continental city is performed.