The impact of the regularization on the economic analysis of rooftop rainwater harvesting system

Abstract

In this study, the economic feasibility of rooftop rainwater harvesting of residential and public/commercial buildings for all 81 provinces of Türkiye is assessed. The Rippl method (RM) is used for optimal storage tank estimation. The net present value (NPV) and the discounted payback period (DPP) are used for economic analysis. Two scenarios were assessed using RM for (I) residential buildings and (II) public buildings. Optimal storage tanks for scenarios I and II were estimated by the selection of minimum roof areas to supply the demand for toilet flushing water for above 90% volumetric reliability. ArcGIS 10.2 was used to illustrate nationwide results of (1) roof areas and storage tank volumes, and (2) the economic analysis. The average DPP of rainwater harvesting system is 36 years for residential buildings and 23 years for public buildings. Based on NPV analysis, 17 out of 81 provinces are economically feasible for residential buildings. The feasibility status in public buildings is 43 economically feasible and 38 infeasible. More savings in public buildings can be obtained in a relatively shorter DPP. Furthermore, regularization is more effective in public buildings than residential buildings.