Riqualificazione energetica dell'edilizia storica. Criticità e strategie d’intervento

The pressing need to operate a cost-effective reuse of historic buildings, with the aim of reducing energy and soil consumption, places us in front of a conflict between the observation of the principles of restoration and the limits imposed by European Community law about the energy consumption reduction. In fact, we know that whenever we operate on a "sensitive" heritage, such as the historic-architectural building, we have to consider the possibility of decreasing its cultural and economic value. The transformations of the historic building derive by the necessity of adapting it to contemporary life exigencies, and at the same time of warranting its conservation, at the architectural and urban scale. To achieve this aim, with reference to system component, usually the interventions are carried out almost exclusively in the inner parts of the constructions, because of legal constraints. The study begins with an analysis of the state of art about energy retrofit of ancient buildings, with particular reference to theory of conservation of architectural heritage and related legislation. Was also carried out a study on bioclimatic traditional characteristics - nowadays very often forgotten - of the fabric and of some architectural episode, and considers the possibility and the potentiality of the use of ancient and new technologies, to obtain a suitable thermal insulation of housing. Starting by these considerations, the present work aims to think over some cultural questions, and to show the results of some studies concerning the historical district of Castello in Cagliari, Sardinia. With reference to this context, specifically, three different buildings typologies will be analysed, emblematic of the urban fabric, and very useful to demonstrate how it is possible to retrain energetically the existing architectural heritage, in full compliance with the modern conservation principles.