A simulation on water film over roofs for the cooling of buildings

A mathematical model on water film over roofs for the cooling of buildings, which incorporated the dependence of water film solar absorptance on the incident angle and the depth of water film, was proposed in this study to allow a more accurate prediction of its thermal performance under different climatic conditions when applied to different buildings. The results by simulation reveal that water film over roofs can significantly improve the indoor thermal environment of buildings compared to dry roofs, and water spray over roofs has the maximum efficiency for the cooling of buildings. Results also indicate that good heat conduction through roofs can assist the improvement of evaporative cooling effect, and the night ventilation is especially important to improve indoor thermal comfort level under the typical hot dry climatic conditions.