Hydrologic Performance of an Extensive Green Roof under Intense Rain Events: Results from a Rain-Chamber Simulation

The water storage capacity of a green roof generates several benefits for the building conterminous environment. hydrologic performance is conventionally expressed by runoff coefficient, according to international standards and guidelines. coefficient dimensionless number defines retention over long period. At scale single rain events, characterized varying intensity duration, reaction scarcely investigated. purpose this study highlight how an extensive roof—having supposed minimum performance, compared intensive one—responds real repetitive simulated in chamber with controlled data. experiment provides, through cumulative curve graphs, behavior sample during four rainy days. events are based on statistical (summarized paper) 25 years data specific location North Italy average rain/year 1100 mm. results prove active response substrate, although thin mineral, quick draining, terms detention intense events. raises questions about better express roofs.