Thermal regulation capacity of a green roof in the Mediterranean climate of Istanbul

Green roofs are considered sustainable practices in the urban environment as they provide several benefits to the city and to the building such as mitigating the urban heat island effect and optimizing the energy performance of buildings. The impact of green roofs on the energy balance of urban building surfaces in warmer climates, such as the Mediterranean, is still under investigation. In this study, 5 years of experimental data recorded between 2015 and 2020 were analyzed in comparison between a non-insulated flat roof and a green roof. The aim of this study is to investigate the thermal regulation capacity of green roofs on the energy balance of buildings and their efficiency as potential UHI mitigation strategies to make cities more resilient. Results of the study demonstrated that despite the limited depth of the substrate and plant diversity, the green roof provided thermal regulation to the building by reducing temperature fluctuations and moderating temperatures for both the building and its surrounding environment. This study provides evidence that the implementation of a green roof could effectively moderate roof temperatures and reduce fluctuations, especially during the summer season. Furthermore, the study demonstrated that even a simple and shallow extensive green roof could provide thermal benefits in a Mediterranean climate. Therefore, due to its structural lower weight, this type of green roofs could be installed on existing buildings and could provide thermal benefits to the building and the city.