Valutazione del comportamento energetico dell'architettura storica. Analisi del metodo di calcolo dello stato di fatto energetico e proposte correttive.

Abstract

A project of energetic redevelopment of a historic building starts from the preliminary assessment of its energy potential and residual performance, in order to tailor interventions and properly address the energy needs according to the characteristics of the building, without losing or jeopardizing its heritage and historic value. This approach is relatively new and specific industry regulations have not yet been developed. The absence of specific legislation means that a dedicated methodology for calculating the energy performance of historic buildings is not included in the best practices of intervention. Currently the energy performance of historic buildings, on which the whole intervention project is based, is calculated with the same tools developed for modern buildings. This research starts from the hypothesis that the two types of calculation available today (analytical standardized method and simplified method) present some limits of applicability, in particular if used for the evaluation of historical architecture, which has technical, geometric, and architectural characteristics that differ significantly from the ones of newer buildings. The use of non-specific instruments can lead to errors in the calculation of the residual energetic performance of buildings. This calculation error can consequently lead to choices of intervention that can be harmful to the conservation of the building, to final level of comfort of its interior, or to its resulting energy efficiency. This study, therefore, critically analyzes the current methods of calculating energy efficiency, with the aim of verifying their validity and limits of applicability by testing them on a sample of historic buildings. This analysis shows significant differences between the results obtained by the analytical method, taken as reference, and the calculations made with the simplified system. It identifies the need for evaluating the energy performance of historic architecture in a different way from that used for recent buildings. At the same time, the application of different methods of calculation to the case studies also highlights the inherent difficulty of finding, for buildings constructed in the past, the necessary data for correctly applying the standard analytical method, regarded so far as the only reliable system. These findings call for the refinement of the simplified method, more suitable to the calculation of the energy performance of historic buildings, and the development of a new instrumental method for the measurement of the energy characteristics of historic buildings, which can be used in parallel with the analytical calculation.