VOLUMETRIC ADDITIONS FOR SUSTAINABLE REFURBISHMENT OF RESIDENTIAL BUILDINGS: FROM THEORY TO PRACTICE Summary In the current negative economic climate, retrofitting and rationalization of the existing residential building stock represent a viable and strategic solution considering two key issues: the improvement of energy performance and the adaptation of the dimensions of the residential units to the emerging needs. The fast increase in households consisting of one or two persons and of five or more is a recognized social trend in most European countries, however more than half of the housing offer consists of flats of standard medium dimensions. Today, the energy demand of the existing housing stock largely exceeds the acceptable levels for sustainable consumption, therefore drastically increasing the relevant operation costs. A research program, currently ongoing at the University of Bologna, Department of Architecture, is focusing on the analysis of the effects of volumetric additions to the existing housing stock, in terms of optimization of the units layout and the relevant energy performance. Starting from a theoretical matrix of strategies for volumetric addition, the research studied specific topics concerning the re-dimensioning of the flats, the increase in energy efficiency and the implementation of equipment on some case studies involving Italian residential buildings daring back from the ’60s to the ’90s. This paper outlines the first results of a simulation of volumetric addition applied to different housing typologies located in different urban settings. Several refurbishment scenarios were performed, related to the densification level required. The volumetric additions were modelled in order to intensify the use of the built estate, broaden the range of the offer and feed a financial mechanism capable of generating resources that can be used for the building refurbishment. Keywords: architectural addition, energy savings, densification, housing renewal Jacopo Gaspari Department of Architecture, Alma Mater Studiorum University of Bologna, Italy, jacopo.gaspari@unibo.it Andrea Boeri Department of Architecture, Alma Mater Studiorum University of Bologna, Italy, andrea.boeri@unibo.it Ernesto Antonini Department of Architecture, Alma Mater Studiorum University of Bologna, Italy, ernesto.antonini@unibo.it Danila Longo Department of Architecture, Alma Mater Studiorum University of Bologna, Italy, danila.longo@unibo.it