Thermal Behaviour of the Diffusive Building Envelope: State-of-the-Art Review

This paper presents a state-of-the-art review of the thermal behaviour of the diffusive building envelope, through which slow and nearly uniform air flows. With the airflow through the envelope, it will exchange heat with solid parts, thus changing the thermal performance of the envelope. The fundamental heat exchange in the air cavities of the envelope is first investigated. Next, the study focuses on the airflow and heat transfer in the porous building materials, in order to assess airflow impact on the thermal performance of the dynamic insulation. The influence of moisture, especially possible phase change, is also discussed. The investigation shows that heat exchange in the envelope will have an impact on the energy consumption of the building. Meanwhile, much work is needed concerning engineering implementation; for example, to provide the suitable analytical methods and to avoid possible condensation.