Cities with high urbanization produce impervious areas. Drainage network overload results in recurring flooding. Much of the damage could be prevented through proper urban planning and good drainage practices. While Low Impact Development techniques have been known for several years, it is essential to encourage the association of this type of technology with conventional micro-drainage structures to increase rainfall runoff at the source where it is generated. Thus, the present work aims to analyze the efficiency of the use of the green roof technique in reducing the peak of the flow and the retention capacity when subjected to heavy rains at the building scale, and also explores its effects in tropical climatic zones with measurements during the summer and fall. The method used was experimental analysis of the Green Roof prototype with bromeliad’s at CESA-UFRJ, whose main results are the hydrogram of each rain event and the runoff coefficient for rainfall in the range of 100 mm/h and 150 mm/h.

Climate change poses a series of challenges to water management to satisfy society’s current and future needs. Considering water an essential resource for life, this research is dedicated to comparing the environmental impacts caused by the conventional water supply system and Conventional Water Supply system complemented with rainwater harvesting, considering in the first one not only the components of the municipal public supply, but also the hydraulic components of the residences until the point of use. A life cycle assessment—LCA—was conducted for the two systems, considering them from the catchment to the point of use. This methodology quantifies environmental impacts throughout the product or process life cycle to obtain sustainable options, from raw material extraction to ultimate disposal. The results expose that the hybrid system represents an increase in environmental impacts. However, at a building scale, this increase was very small, and this can be seen as favorable to the hybrid system due to the benefit it brings. The seven percent reduction in water demand over the conventional system can represent significant relief in regions that already have water stress as a reality. This study has the potential to guide managers and designers of public water policies, providing data for a better decision-making process.