Methodology to Optimize Rainwater Tank-sizing and Cluster Configuration for a Group of Buildings

The behavior of a rainwater harvesting system depends on some variables that cannot be controlled, such as rainfall, building roof size and water consumption. The selection regarding rainwater tank-size will affect the performance of the system and the cost-benefit ratio. The criterion employed for this selection is based on the need for volume-storage and typically, yield large-sized rainwater tanks, especially when the amount of rainwater is higher during rainy seasons. This article presents a methodology for modelling rainwater harvesting, storage, and water consumption, for different configurations of a set of buildings, called clusters, where all buildings collect, store and consume water. This methodology allows for analyzing with different indicators, what is the best recommended configuration and tank-sizing, based on configuration and storage ratio exhibited, thus avoiding the situation of being underutilized. The proposed methodology is applied to a case of study at a university, in Mexico City. In this study case, the dynamics per day is modeled over a year, considering monthly rainfall averages, over 2 groups made up out of 4 buildings with different collecting capabilities and consumption each, allowing for the analysis of 9 cluster configurations and 4 rainwater tank-sizing dimensions. The results are analyzed by means of annual indicators such as: the decrease in the volume used from the public water network, the days of autonomy of the system, and a coefficient R (which relates the volume spilled to the empty volume). This coefficient is then used selection regarding rainwater tank-sizing and the most recommended cluster configuration.

Automated summary

This article presents a methodology for modeling rainwater harvesting, storage, and water consumption, aiming to analyze the best configuration and tank-sizing selection based on various indicators, to avoid underutilization.