The adoption of green roofs for the retrofitting of existing buildings in the Mediterranean climate

Abstract: In recent years, the demand for air conditioning systems has increased considerably. Consequentially, the energy demand for building cooling has become a serious concern. In particular, the energy peak demand that is intensified by the urban heat island (UHI) effect is often a critical issue for the outdated electricity infrastructure in many countries. In order to rationalize the building energy consumption while ensuring indoor thermal comfort, this paper explores the possibilities offered by the retrofitting of existing uninsulated roofs in combination with night natural cooling strategies. To this end, a case study was selected in order to investigate the performance of an extensive green roof (GR) with and without natural ventilation (NV). The selected building is located in Catania, southern Italy, in a very mild climate. Free-running conditions were evaluated together with air conditioning conditions during the daytime and free cooling via natural ventilation at night. The hourly variation of cooling loads during a typical hot day and the overall performance of the different investigated scenarios were compared. Finally, suggestions about the value of the different investigated building retrofitting strategies are reported.