A method for assessing buildings’ energy efficiency by dynamic simulation and experimental activity

Buildings’ thermal-energetic assessment and the relative proposal of new technical solutions applied to both summer and winter analyses has a strategic role in increasing the year-round performance of buildings.Buildings’ dynamic analysis is by now a well-established procedure to study effective building energy performance given real climate considerations. Then in this work, a concise and effective methodology for analyzing buildings’ thermal performance in a dynamic environment is proposed and applied to different case studies, consisting of single-family residential buildings’ prototypes. This procedure is aimed to define different performance levels by proper non-dimensional indexes named thermal deviation indexes (TDI). These indexes values could express in a concise way buildings’ thermal behavior, different optimization strategies impact, sensitivity analysis results.Buildings’ prototypes representing the case studies are three free-floating houses where the architectural shape role and the sensitivity of different envelope features are analyzed, also supported by experimental results regarding envelope properties measured on existing residential buildings in Italy. The three prototypes are respectively designed to optimize summer or winter energy performance or to represent the typical Italian house before and after energy efficiency regulation is implemented. To better define the important envelope parameters necessary to calibrate the numerical models, experimental activities are conducted. 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 modern building.The results of the dynamic analysis are expressed in terms of TDI values, to define buildings’ thermal performance with respect to the variation of all the considered architectural and envelope’s properties (i.e. architectural layout, mass and insulation, roof reflectance, Solar Heat Gain Coefficients of windows’ glasses, weather data) within a specific climatic context.For validating the proposed method, the obtained TDI results are 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.

► We propose a new methodology for the evaluation of buildings’ thermal-energetic performance.
► We express year-round performance by an appropriate objective function.
► The procedure allows to translate dynamic simulation results into buildings’ energy guidelines.
► The proposed index shows an important correlation with indoor thermal comfort international index DH.