Multi tank model for energy efficient rain water harvesting

Abstract

Rain Water Harvesting (RWH) to supplement service water is an important aspect of sustainable development. As such, much research has been carried out on optimizing the system components of RWH systems so that a maximum water saving efficiency (WSE) can be reached with a minimum storage capacity, enabling the outlay on capital minimized. However, if RWH is to proliferate it should be able to operate in par with centralized service water, supplying collected rain water to user points reliably. This is usually achieved by pumping the collected rain water to service points utilizing electricity, which in fact could negate the positive gains of RWH with regard to principles of sustainability. By introducing a multi tank model, where a smaller tank is installed for each floor at its roof level in addition to the main storage tank, a solution can be reached with superior system performance. In the model, the roof collection enters the top most tank first and then cascades through multiple tanks in multi story situations, before being collected in the main storage tank, vastly improving the overall energy efficiency of the system. The model, not only addresses the space and structural issues of the building but also ensures that the aesthetics of the building envelop is not disturbed due to smaller sizes of the upper tanks.