Modifiche funzionali e volumetriche nelle previsioni di piano: impatti ecologici morfologici ed economici nella città di Voghera (Pv)

In the cultural context of sustainable development objectives, reduction of natural resources uses, enhancement of territorial and urban resilience and implementation of greener and healthier cities, one of the most relevant challenges for the future is the promotion of regeneration, redevelopment and reuse strategies and actions in urbanized areas in order to limit land consumption, defined as the increasing of artificially covered surfaces and the decreasing of agricultural, natural or semi-natural areas. Soil sealing represents a very impactful use of land, as it causes irreversible loss of biodiversity and key ecosystem services. Many efforts have been made to increase soil conservation and its value: sometimes, in urban plans and policies definition the topic is strictly linked to economic, morphological, and social issues that influenced its development. In this context, the application of an index to regulate soil permeability is essential to identify flexible and resilient solutions. The main aim of the presented dissertation is to take action to reduce building impact and promote the implementation of green areas and surfaces as a specific tool for environmental mitigation and compensation. The first phase of the project consists in calculating the sealed soil in three areas of Voghera (PV) Municipality, with different morphological and typological features. To perform this work, the Biotope Area Factor (BAF), an index focused on the integration of urban planning and ecology, was used with a GIS-based tool. The application of BAF is scientifically legitimized by a calculation algorithm that is based on the use of ecological permeability coefficients with values between 0 and 1, assigned according to specific surface characteristics and summarized in tabulated values. The method, or other similar methods, is used since the 1990s both in Italy and in other countries worldwide. With reference to the obtained results, the possibility of bringing the building index (known in Italian urban planning regulations and as “Indice di edificabilità fondiaria If”) to saturation by working on the existing volumetry in compliance with the urban planning indices and parameters imposed by the PDR, was evaluated. The additions of volumes to the existing buildings aim at increasing useful surfaces for the increasing of ecological services, the enhancement of buildings performance and functional levels. Secondly, an alternative mitigation option was simulated to allow each area to achieve the assigned target BAF by proposing Nature-Based Solutions (NBS). The measure of greening roof surfaces is the key to upgrading existing buildings, improving urban microclimate, and sustaining biodiversity, for a greener, healthier and more attractive city. From an urban spatial resilience perspective, the aim of the research is therefore to provide a case study that aims to enrich the debate on soil sealing and provide scientific support for future sustainable urban planning strategies.