Reliability, Optimization and Economic Analysis of the Rainwater Harvesting System from the Rooftop

Performance assessing and economic analysis of rainwater harvesting systems, which is one of the most effective methods to deal with the crisis of water scarcity, will lead to better management of these systems. The purpose of this study was to evaluate the performance of rainwater harvesting systems, Musanejad dormitory and sports club buildings in Tarbiat Modares University, Faculty of Agriculture were selected as study areas. Then, the 22 years old daily precipitation data of the Chitgar Weather Station was prepared. System simulation was performed in Matlab software and reliability and overflow ratio of storage tanks were determined. The Genetic Algorithm was used to determine the optimal volume of the tanks of both buildings and finally, an economic analysis of these systems was carried out using the Net Present Value method and benefit-cost ratio. The results showed that the optimum volume of tanks for the Sports Club and Musanejad dormitory was 2,415 and 1 cubic meters, respectively. These tanks can store up to 82 and 120 cubic meters of water per year, respectively. The results also showed that the performance of rainwater harvesting systems was beneficial for the Musanejad dormitory but had no economic justification for the sports club due to low demand and high overflow.