Reliability and Economic Analysis of a Rainwater-Harvesting System for a Commercial Building with a Large Rooftop Area

The water shortage problem faced by many countries requires a practical engineering solution. The reliability analysis of a rainwater-harvesting system (RWHS) installed at a commercial building of AEON Taman Universiti located in Johor Bahru, Malaysia, was based on the rainfall pattern, rainwater use, and rainwater storage tank. An economic analysis using the net present value (NPV), return on investment (ROI), and benefit-cost ratio (BCR) was performed to assess the optimal management of a RWHS installed during the construction and retrofitted after the operation of a commercial building. The results showed that the balance of water supply and demand is reliable for implementing a RWHS and the optimal management of a 1000 m³RWHS tank installed during construction could be more promising than that retrofitted after operation of the AEON Taman Universiti commercial building. The operation of a RWHS installed during the construction of a building is obviously more feasible because the NPV, ROI, and BCR values tend to be high. The reliability and economic analysis of RWHS installed during construction and that retrofitted after operation of a commercial building demonstrated the benefit of RWHS installation will contribute to effective water management as part of future building design.