Deep Renovation in Sustainable Cities: Zero Energy, Zero Urban Sprawl at Zero Costs in the Abracadabra Strategy

The energy efficiency challenge in buildings mainly concerns the energy efficient refurbishment and investments in existing buildings. Yet, today, only 1,2% of existing buildings is renovated every year in Europe. The actual investment gap in the deep renovation sector is due to the fact that high investments are required up-front, and they are generally characterized by an excessively high degree of risk, long payback times, and the general “invisibility of the energy benefit”. ABRACADABRA is an H2020 project that aims to activate a market for the deep renovation of existing buildings through a major transformation of the buildings aiming at the increase of the real estate value. This increase is essentially given by a volumetric addition (Add-ons) whose added value, once capitalized in terms of selling or renting, is able to reduce the payback time of the investment. Several pilot case studies have been used to test the efficacy of the strategy. At this stage of the project, a challenging sector like the social housing sector is also being explored to verify if a retrofit strategy including add-ons and densification could help boost the renovation of the public and residential housing stock. The process is based on a cost-effectiveness analysis. In this paper, to demonstrate how the densification action could be an effective solution to promote energy efficiency interventions and new business models to shorten the payback time of renovation investments, five different buildings have been studied. The simulation made on these case studies is divided into three steps: a feasibility study, an energy saving analysis, and a payback time calculation. In the last phase of the study, the financial assumptions are fundamental. In the case of social housing, the sale, rental, and social values were considered and combined to find the best opportunity of incomes and the shortest payback time. Moreover, additional issues were taken into account regarding the regulatory aspects and the technical feasibility of this type of approach. Implementing this strategy necessitates adding new units on the rooftop or on the side of an existing building. This might meet obstacles, such as urban regulation restrictions and the consensus among tenants. To overcome these obstacles, the project promotes new policy recommendations that municipalities could approve, and counterbalanced measures to help residents embrace the ABRACADABRA strategy.