Low energy and low cost strategies for the social housing retrofitting The article aims to explain the improvement in the strategies of living standards, energy efficiency and cut in carbon dioxide emissions in the existing social housing sector through low cost transformations of flexible, open,“intelligent” retrofitting which, with the inhabitants’ participation, succeeds in realizing a residential organismevolving under the ever-increasing need of continuous changes and adjustments of flats characterized by linked units, intermediate spaces, multifunctional environments which are formed in space and time. The two cases proposed, planned and in progress are in Central Italy in the climatic zones C and D. The first is in Senigallia (Ancona) and is carried out by the Itaca Department, Lab. AMSA; the second is in Nettuno (Rome), realized by the studio Battisti Tucci. Their aimis to invert radically the process and the systems of the use of energy resources and to get back the tradition in employing passive solar and cooling technologies for the urban eco-efficient development. In these cases the experience of experimentation of urban building retrofitting with low costs represents the attempt to shift into urban architectonic forms–and therefore into the living forms–the potentials of local culture together with environmentally sustainable use of the energy resources.