Building energy efficiency assessment by integrated strategies: dynamic simulation, sensitivity analysis and experimental activity

Thermal and energy dynamic analysis of buildings is a well-established procedure to evaluate the effective building energy performance, considering real climate. The proposal of new technical solutions and innovative strategies to be applied for both summer and winter period has a fundamental role also considering the IPCC suggestions and the EPBD European Directive implementation. In this paper a synthetic but also exhaustive method for thermal dynamic analysis of buildings is proposed. It is based on performance levels assignment, defined by proper non-dimensional indexes (TDI, Thermal Deviation Index) that allow to express the building behavior and the sensitivity analysis results, in relationship to the climatic context. The proposed methodology is then applied to different case studies consisting of numerical prototypes of free-running residential buildings to evaluate first the architectural shape role and then the sensitivity of different envelope features, characterized also by experimental measurements conducted on real Italian residential buildings. The prototypes are designed to optimize respectively summer or winter energy performance or to represent the typical Italian house before and after energy efficiency regulation coming into force. To better define some important parameters necessary to calibrate the numerical models, experimental activities are carried out. In particular, thermal insulation level and roof reflectance, characterized by means of spectrophotometrical measurements, are measured both in the case of an old traditional Italian building and in the case of a new one. The results of the dynamic analysis, concerning all the considered variables (mass and insulation, roof reflectance, Solar Heat Gain Coefficients of glasses, weather data, etc.) are defined by TDI values that make it possible to evaluate and to compare the role of each element for defining the building thermal performance, also related to the specific climatic context. The results obtained using the proposed method are also compared with those obtained from existing procedures. In particular the TDI values are correlated to an adaptive comfort indicator, for verifying how much the TDI could be effective for evaluating free-running buildings thermal performance during both summer and winter period.