The value recapture of complex urban transformation interventions: a rational procedure for the fair share of public and private benefits

The benefits generated by the urban transformation interventions can often favour the private property owners or developers by increasing their gains (effective or potential) and therefore reducing the acquirable resources for the public city’s construction. However, due to the requirements of achieving the sustainable development targets established by the 2030 Agenda the process of the construction of the public city should appropriately address the implementation of value recapture’s principles in the assessment of the benefits generated by complex urban transformation interventions. For these reasons, tools like the Extraordinary Urbanization Contribution (EUC) – established in 2014 with the art.16, co.4 of the Italian Presidential Decree no.380/2001 – have recently gained renewed importance. Aim of the work is to provide a decision support model for the assessment of the plusvalue generated by complex urban variant intervention, in order to detect the effects that the discount rate used for representing the time and the risk in the application of the Discounted Cash Flow Analysis (DCFA) for determining the transformation value, can have on the feasibility of the intervention and, consequently, on the public and private benefits. The implementation of a rational procedure based on the application of the mathematical optimization’s principles to a case study in the city of Bari (Italy), allows to highlight how the discount rate may significantly change the urban parameters from which the feasibility of the urban variant depends and the fair share of the public and private benefits.