Numerical investigation of the effects of different influencing factors on thermal performance of naturally ventilated roof

Ventilated roofs can improve thermal performance and reduce the energy consumption of building roofs. In this study, the optimal design parameters and adaptability of naturally ventilated roofs were determined through numerical investigations of the effects of different influencing factors on their thermal performance. A three-field coupling numerical simulation method considering temperature, flow, and solar radiation fields was used to improve simulation accuracy. The research results show that the optimal air gap layer thickness of a naturally ventilated roof increases with increasing roof length, which has not been considered in previous studies. The peak interior surface temperature of the ventilated roof increases with increasing outdoor atmospheric pressure. Ventilated roofs with a 30 degrees -40 degrees slope have a stronger stack effect and can better discharge solar heat gains when compared to roofs with other slopes. Interior surface temperature is reduced when phase change materials is set in the upper rather than the lower roof during summer. Phase change materials should be set in the upper roof to save energy. Small damage holes in the upper roof don't apparently affect the ventilated roof thermal performance. The findings of this study can guide optimization design and help evaluate the energy-saving effects of naturally ventilated roofs.