Indagine dei fattori di degrado e proposte di riqualificazione energetica nelle residenze sociali ad alta densità. Il quartiere Pilastro di Bologna

The sequence of events that, in Italy, has characterised the development of Social Housing since the Second World War until today has made it necessary to face the renovation of social residential buildings. Despite the short period of time that has elapsed since their construction, the condition of large housing estates built in our country between the 1960s and 1980s are not only largely unfit for purpose but they also present substantial limitations with regards to energy efficiency. In this respect, research has defined a methodology to approach the regeneration of buildings of reference and has assumed some strategies to improve energy efficiency. After outlining the latest developments regarding public and private housing construction both in Italy and in Europe since the post-war period, some representative Italian residential areas with high density living have been analysed taking into particular consideration their most important features. Among these areas, an suitably representative case study has been identified in the “Virgolone” housing development which is located in the Pilastro district of Bologna. In this large housing estate, consisting of more than two thousand units, the technical and architectural features of the three main urban sections have been firstly identified. This sections correspond, in turn, to three periods of construction (1964-1986) whose predominant differences have been highlighted. The variety of housing types, of building systems and of management policies has characterized a diversified development which, depending on the building, has sometimes produced a variety of results in the same housing estate. Defining a strategy for effective renovation necessitates acquiring a preliminary and detailed knowledge of the building of reference, based on an analysis of a multiplicity of elements, in particular of those elements which are most affected by obsolescence and that influence its performance directly. The cognitive survey investigated the performance deficit of technological units which make up the building envelope and assessed the degradation phenomena related to structural and construction features, contextualizing the choices in a given historical moment. This survey has been followed by a critical evaluation of the qualitative analysis carried out and of the instrumental data acquired, which has allowed to focus the attention on the most important problems of the individual residential units and to gain a basic knowledge necessary to undertake the following phase, which consists of defining the possible intervention of renovation. In this regard, the energy consumption of the building has been calculated, comparing it with the energy performance index defined by legislation. The results of this in-depth analysis has contributed to formulating scenarios of intervention through following transformation stages, proposing different project hypotheses for solutions for which assessments of the intervention costs and of the time it would take to have a return on the investment have been calculated.