How Cool Pavements and Green Roof Affect Building Energy Performances

Abstract

The urban heat island effect amplifies the global warming phenomenon with sensible aftermaths on the building energy consumptions. The absence of green areas, open water channels as well as the lack of free unsurfaced spaces creates a sort of urban cap and a heat reflection effect, from the bottom upwards, which persists in the early hours of the night. This heating effect exacerbates the use of air conditioners which, if on one hand helps to cool houses, on the other hand rejects outside hot air hindering the cooling effect of nighttime air. The aim of this study is to analyze the effects of urban heat island mitigation techniques on the building energy performances, such as cool pavements and green roofs. Measured temperatures were used to calibrate a model of a densely populated district in Rome by means of ENVI-met software. It was subsequently carried out an energy analysis through the use of TRNSYS in order to study the energy behavior of a reference building in its urban context in function of the variation of the boundary conditions.