The Add-ons strategy. Volumetric additions for deep energy renovation of existing buildings

The main European energy challenge mainly concerns the energy efficient renovation of the existing buildings stock, which counts for two third of the overall European energy consumptions; yet up until today, only 1,2% of existing buildings gets renovated every year. The actual investment gap in the deep renovation sector is due to the fact that consistent investments are required up-front and they are generally characterized by an excessively high degree of risk and long payback times. The ambition is to define a comprehensive renovation methodology, where technology and society priorities meet, in the search for a new construction type, tool and trigger at the same time in the Energy Renovation of Existing Buildings The main objective of the research presented in this volume consists in the validation of an integrated design methodology based upon the creation of additional volume on existing buildings (Add-Ons) intended as roof-top or aside extensions, enclosures, parasites or façade transformations. The Add-Ons are intended as the core and main instrument of an innovative strategy that has been proven able to overcome the actual barriers, increase the feasibility of energy renovation in the residential field and ultimately foster the building renovation market. Indeed, the research hypothesis is based on the assumption that an empowering synergy can be created between the old and the new, not only in structural, functional and architectural terms but also in economical and social terms. The research will test and prove the technical and economical feasibility of the Add-ons strategy for Deep Renovation through several design experiments carried in a series of case studies in different European contexts (Italy, Germany, Greece). The validation by design helped defining a modular and adaptive approach that could directly express the internal programmatic need for transformation and contextually respond to the structural and energetic emergency of the existing building. The case study have shown that the beneficial effect of the Add-on depends on the existing market variance between the cost of construction and the real estate value as well as the energy prices and reduction potential. However, considering three different scenarios with different construction market trends, the Add-on strategy has proven to be effective in reducing the payback time to less then five years, thus being able to foster a concrete revolution in Deep renovation market and viability. The highly replicable nature of the proposed methodology, the important impact on the market and the possibility of overcoming the existing restrictive social barriers highlight the innovation character of the proposal indicating the path towards an effective turn-around in the energy renovation of European buildings and cities, a step forward in defining a new paradigm of sustainability.