Energy analysis of ventilated roof with extended top in hot regions

An extended top of the roof can induce the upflowing wind which flows close to the wall and in this way it increases the intake airflow rate in the air gap. A model was set up to save energy with the consideration of a suitable thickness of the air gap and a suitable length of the extended top. The Computational Fluid Dynamics (CFD) was employed to simulate the wind field in the ventilated roofs with extended top and the cases were carried out according to Changsha’s climate parameters in China. The results show that the extended ventilated roof works very well in summer.


The thermal performance of the building envelope is mainly required for guaranteeing a comfortableand hygienic interior climate. A roof is a part of the building envelope which provides protection from thethermal damage of the sun. To improve this protection ability, we can consider using a ventilated roof,which has a ventilation layer known as a cavity, beneath the roof cover panel.The objective of this study is to evaluate the influence of such factors as the slope of the roof, size orshape of the openings (i.e.

Numerical analysis of heat and mass transfer in a passive building component cooled by water evaporation.

Describes details of a passive building component consisting of a ventilated roof with a maintained wet lower surface of the cavity over which the external air flows. Numerical simulations were carried out for thermal performance evaluation purposes of the thermal field, flow field and water vapour concentration of air within the duct. Suitable procedures were coded and linked to a commercial program for computational fluid dynamics, in order to obtain an estimate of the thermal cooling flux on the wet surface.