Thermal Behavior of an Extensive Green Roof: Numerical Simulations and Experimental Investigations

Green roofs produce many environmental benefits, since they can both mitigate the heat island effect and improve the energy efficiency in buildings. In particular, the Italian building stock built before Seventies (around 58%) is characterized by a lack of thermal insulation on the roof surfaces, so the application of a green roof can be an opportunity to enhance the energy performance of those buildings. In this study, the authors investigate the thermal behavior of a prototype of extensive green roof installed on a terraced building placed in the Mediterranean area, both through experimental measurements and dynamic simulations. The aim is to assess the feasibility and performance of this solution during the summer period. The results of the simulations indicate a strong reduction in the peak outer surface temperature if compared to the existing roof, as well a significant decrease in temperature fluctuations. The results also allowed to assess the reliability of the simulations, if compared to experimental data. The model of the green roof proved to be sufficiently reliable, even if some minor improvements may be expected