Green Water from Green Roofs—The Ecological and Economic Effects

Agnieszka Bus and Anna Szelągowska
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Agnieszka Bus: Department of Environmental Development, Institute of Environmental Engineering, Warsaw University of Life Sciences—SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland
Anna Szelągowska: Innovative City Department, Collegium of Business Administration, SGH Warsaw School of Economics, Niepodleglosci 162, 02-554 Warsaw, Poland

Sustainability, 2021, vol. 13, issue 4, 1-14

Abstract: Green roofs (GRs) have been one of the most popular solutions for water harvesting in urban areas. Apart from their water retention role and increasing biodiversity, they constitute the missing link between the built and the natural environment, which is required for sustainable human living in cities. This paper aims to calculate the ecological (EE) and economic effect (EcE) of water harvesting via GRs, by contrasting with a traditional roof, and to perform an economic analysis of the social cost benefits that GRs generate during their life cycle, using the Net Present Value (NPV) method. All the calculations and analyses were conducted for both intensive and extensive GRs in 11 of the largest municipalities in Poland, with a population of >250,000 inhabitants. According to the results of this study, water retention and the economic and ecological effects of GRs are highest in the municipalities with the highest assumed number of GRs (Warsaw, Krakow, Wroclaw, and Szczecin). The average EE and EcE equals 507,000 m 3 /yr and 621,000 USD/yr. The NPV results show that the effectiveness of investments in intensive GRs is, to a certain extent, more significant than in extensive GRs and the average equals 60.77 and 4.47 USD/yr for intensive and extensive GRs, respectively. The results could serve as a reference for the evaluation and optimization of the energy efficiency of rainwater harvesting schemes, in European cities.

Keywords: ecosystem services; green economy; green roof; internal rate of return; net present value; rainwater harvesting (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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