The Assessment of Density Bonus in Building Renovation Interventions. The Case of the City of Florence in Italy

The European Green Deal indicates the renovation of both public and private buildings as a key element for the improvement of energy efficiency in the building stock, in order to reach the goals of the document itself. New incentives, also including density bonus, can significantly contribute to foster diffuse actions. In Italy, the density bonus is under testing: the current framework has produced profitability for regeneration in some areas and unprofitability in others. This has led to a non-diffuse renewal, widening differences in richness and quality throughout territories subjected to the same reward measure. A territory is characterized by a high degree of typological and qualitative fragmentation and dissimilarity. Thus, the aim of the present work is the construction of a model that allows for identifying the entity of the reward measure in terms of density bonus. Density bonus can determine the feasibility of renovation interventions—in economic-financial terms and in relation to urban impact—taking into account the characteristics of the context (or micro-context) where they are performed. The research model is based on a Balance Sheet Model and is applied to the city of Florence. The model suggests an innovative approach where urban, landscape and environmental impacts produced by the density bonus are evaluated according to the economic amount needed for their mitigation. The expected results in the application of the model consist in the definition of an iso-bonus map organized by areas.