Numerical analysis on thermal performance of naturally ventilated roofs with different influencing parameters

• Thermal performance of a ventilated roof is investigated by varying its parameters.
• Effects of five conditions on thermal performance of ventilated roofs are analysed.
• The roof slope 0.33–0.4 is recommended.

Ventilated roof can reduce the cooling load during summer period by decreasing transmitted heat flux of the building structures exposed to the solar radiation. In the present work, effect of different influencing parameters on thermal performance of naturally ventilated roofs on a residential building in Northeast China has been investigated numerically based on computational fluid dynamics (CFD), such as air gap thickness, roof slope, exhaust outlet size and absorption coefficient of external roof surface. The results show that the effect of ventilated layer on the temperature delay of roofs is strong, but the effect on the delay time is relatively weak. The air layer thickness, roof slope and exhaust outlet size also play an important role in the thermal performance of ventilated roof.