This paper discusses an energy upgrading on a social housing building in Margherita di Savoia, a small town in the Puglia Region, Italy, and the relationship with urban heating island. The building is one of the pilot sites of the REHOUSE project (funded by Horizon Europe Programme), specifically located in the “Capitanata Zone” considered one of the most socially vulnerable areas. An energy diagnosis was performed to assess the initial energy condition of the building. The objective is to define a baseline consumption, to be used for the evaluation of the energy improvement interventions modelling innovative technology with TRL5. In this way, actions on the envelope and actions on thermal and electrical systems can be defined. Energy efficiency measures are planned on the building envelope and the heating system one. An innovative centralized system will be built using a thermal stratified storage tank. The starting point was the creation of the BIM model of the DEMO building in Margherita di Savoia. This procedure required the validation of the numerical model, in fact, an appropriate calibration of the consumption of both energy carriers was carried out. Building redevelopment becomes a tool for urban redevelopment through the study of the effects of soil desealing of the areas surrounding the building, their greening and the use of certain materials and colors on the facades of the building to limit the negative consequences of phenomena such as the heat island. The final objective of the work is to understand which types of building interventions and on the open spaces surrounding the building are the minimum necessary to reach the standards of energy efficiency of buildings required by the European Union.