Hydrologic Effectiveness and Economic Efficiency of Green Architecture in Selected Urbanized Catchment

This paper presents a numerical assessment of the influence of green roofs applied in the urbanized catchment on the rainwater outflow hygrogram as well as costs and economic efficiency analysis of the proposed green architecture application. The campus basin of the Lublin University of Technology, Poland, was selected as the object of the study. Three variants of extensive green roof applications were designed. The numerical model of surface runoff was developed in US EPA's SWMM 5.2 software. The simulations were performed for three different rainfall events of various intensities and durations. The cost efficiency of the proposed green architecture was assessed by the Dynamic Generation Costs indicator, while economic effectiveness was tested by Benefits-Costs Ratio and Payback Period determined for all assumed variants. The determination of economic efficiency indicators was based on investment and maintenance costs estimation, assumed discount rate, and time duration of assessment. Results of numerical calculations showed up to 16.81% of peak flow and 25.20% of runoff volume reduction possibly due to the green roof application. All proposed variants of green roof applications in the studied urbanized catchment were assessed as generally profitable due to possible financial benefits related to heating and cooling energy savings and avoiding periodical change of bitumen roof cover.