Design methodology of passive houses in different climatic zones in Italy

The "Passivhaus" standard has become a set of rules and suggestions that allow any architect or engineer to design a house with very low or zero energy consumption. The simple application of the "Passivhaus" building code does not necessarily mean that the expected comfort conditions will be achieved, since the rules were first developed in colder climates, which are very different from the Mediterranean climate typical of large areas of the Italian territory. This paper aims at studying the potential critical issues of the "Passivhaus" standard when applied in Mediterranean and Southern European climatic zones, where the summer cooling demand is as important as winter heating one. In this paper, a single family, two floors passive house with a defined size and shape was designed and studied in three different Italian cities (Rome, Palermo and Bologna) characterized by different climatic zones, with the aim of evaluating the energy performance in winter and summer. From the results of this study it was possible to show that passive buildings internal comfort can be controlled and optimized by controlling the ventilation rate, with a minimal utilization of heating and cooling systems. Moreover, the comfort goals can be reached with thinner insulation on the walls, than suggested by the "Passivhaus" standard, and using the traditional building technologies normally applied in Southern Europe.