Widespread overbuilding, the prevalence of asphalt surfaces on green areas, and the use of building materials with low heat dissipation abilities are among the main causes of Urban Heat Islands. Within urban areas, evapotranspiration and shade from plants can significantly reduce the UHI phenomenon, help in stormwater management, and reduce building energy consumption. The goal of this work is to analyze the hydraulics and energy performances of an experimental extensive green roof at the University of Calabria (Italy) in Mediterranean area. This study confirmed that green roofs significantly mitigate storm water runoff generation in terms of runoff volume reduction and peak attenuation, and improve the thermal performance of buildings and the internal comfort of indoor spaces.

In urban environment green roof represents a sustainable solution for mitigating rainfall-runoff volumes delivered to combined sewer systems. Despite numerous studies have been focusing on long-term monitoring of green roof in urban watersheds, few literature has analysed and built models for predicting the hydraulic efficiency of a green roof.This study proposes a conceptual model to predict the hydraulic behaviour of a small-scale physical model of a green roof. The model green roof is idealized as a system consisting of three individual components in series. Each component is subjected to different hydrologic and hydraulic processes and therefore, is treated as a separate module. A mass balance equation is applied to each component, taking into account the specific phenomena occurring in each module. The model is loaded by a series of constant rainfall intensities. The physical model testing is also performed.Resultsdemonstrate the model is accurately able to predict the hydraulic behaviour of the system as compared to measured data. In future research study this model will be applied to long-term basis simulations

A small size laboratory test-bed has been realized at the University of Genoa in order to evaluate the drainage capacity of permeable pavements by monitoring inflow, runoff and subsurface outflow. The laboratory test programme has been designed in order to investigate the influence of the rainfall intensity and pavement slope on the hydrologic response of permeable pavements. Four permeable pavement systems realized combining two paver typologies (concrete cell and pervious brick) with two filter layers made of recycled glass aggregate and a mix of gravel and coarse sand are tested. The hydrologic response of permeable pavements is analysed by using a dimensionless volume index (discharge coefficient) and a timing index. Laboratory results reveal that the hydrologic performance is fairly consistent for all the investigated permeable pavements. The recycled glass aggregate turns out to be a valid solution. No surface runoff occurs even at 98 mm/h rainfall intensity