Optimization of air tightness and night ventilation for Passive houses in Italian climates under Fanger and Adaptive comfort models

In Central and Northern Europe several thousands homes conform to the Passivhaus standard havebeen built. The applicability of this Standard has not yet been sufficiently tested in warmer climates,where reducing cooling needs under growing summer comfort requirements poses a challenge.The IEE Passive-on project has drafted a proposal to adapt the Standard to the conditions thatcharacterize Southern Europe. Compared with the original definition, one of the main changes is theintroduction of explicit requirements on internal comfort during summer, in parallel to a limit to energyneeds for cooling.The dynamic simulations conducted to test the new definition of the Standard in the context ofSouthern Italy (e.g. Palermo) show that the requirements identified by the Standard Passivhaus canbe met by simplifying the envelope technologies (e.g with a lower level of air-tightness compared tothe northern version) and adopting passive cooling strategies (e.g. night ventilation) appropriatelyadjusted. Some ventilation plant simplifications can be compensated by an increased role of thermal insulation and some of the choices can make energy needs tend to zero.Thermal comfort is characterized according to Fanger PMV in cases where mechanical cooling is still required for peak situations, and according to the Adaptive Model where no mechanical cooling is required (see standard EN15251). Authors are performing energy and comfort measurements inrecently built Passivhaus in Italy. Some analysis on non-domestic buildings with a similar methodology has been performed in the framework of the KeepCool2 project and some results arepresented.