Sustainable Management of Urban Green Infrastructure – The Challenge of Providing High-Quality Green in Multi-Storey Residential Construction



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Vienna is known as one of the most liveable cities worldwide (Mercer, 2015), not least because of Vienna’s green infrastructure (GI). These qualities of life and the trend of urbanisation lead to strong population growth in Vienna. It is predicted that the Viennese population will grow from 1.8 million (2015) to 2 million in 2029 (MA 23, 2014); to offer living space, the creation of up to 120,000 new homes is planned until 2050 (MA 18, 2014). The growth and the resulting exploitation pressure on the (green) areas pose a major challenge for the City of Vienna. The loss of green space induced by land use results in the reduction or loss of ecosystem services. The negative effects of the decline of green areas and the increasing soil sealing already occur especially in areas of high population density. Furthermore, increasing heat stress and risks related to natural disasters like the flood event in 2002 show the importance of green space in urban areas for the maintenance of ecosystem functions. Therefore, a challenge of the next years will be to maintain a high-quality and efficient network of GI.

At the moment, the floor area ratio (“Geschoßflächenzahl”) and other values like the degree of soil sealing, the density rate for buildings, building heights etc. are the defining parameters for urban development in Vienna and regulate the degree of building coverage. The supply of the neighbourhoods with open/green space is determined only indirectly. Besides, those parameters are not able to state the quality of green space for humans. Vienna has already recognised the importance of GI and develops guides for developers and urban planners to contribute to encourage GI in the city (MA 18, 2014; MA 22, 2013; MA 22, 2015). But a clear framework for the conservation and provision of minimum standards for urban green space, however, is still missing; incentives for implementation of GI elements are primarily given through grants.

Some cities have developed defining parameters or policy instruments for

GI to enable a management of open space supply and quality (e.g. Berlin: “Biotope Area Factor”; Malmö: “Green Space Factor”; Seattle: “Green

Factor”, Helsinki...), but in the current practice of applying the green space factors almost only ecological aspects are taken into account (Kruuse, 2011; Szulczewska et al., 2014). Socio-cultural aspects such as usability, aesthetics or recreation are rarely considered. For urban planning and administration it would be important to start thinking about a green space factor which, beneath size and space consumption, also takes into account socio-cultural aspects.

The main objective of the “AddedValueGreen!” project was to develop a green

and open space factor (“Grünflächenfaktor” or “GFF”) which encompasses regulating, socio-cultural and economic effects of urban GI (uGI). The focus was on the management and intervention of private and housing-related spaces to secure a certain amount of high-quality open/green space on building lots. Through the evaluation of housing projects by using the GFF, deficits in the green space supply and quality can be identified and recommendations to improve the GI can be derived. Furthermore, it will be possible to integrate this evaluation tool into other planning levels or management tools.