Experimental assessment of a zinc-titanium ventilated façade in a Mediterranean climate

Abstract

An experimental study was carried out on ventilated façades with zinc-titanium cladding in a hot-summer Mediterranean climate. The aim was to investigate the thermo-physical performance, verifying the effect of the following parameters: (i) the height of the ventilation channel; (ii) the external climate conditions (direct solar radiation, wind); (iii) the exposure to sunlight; (iv) the type of external facing. The study involved the simultaneous monitoring of walls with zinc-titanium cladding with ventilation channels of different heights (4m, 8m and 12m) and different exposure (south, east and west). The data obtained were also compared with those measured on ventilated walls with clay cladding (12m south-facing wall).The results allowed to experimentally verify for the studied façades the strong relationship between difference in internal-to-external air temperature and airflow rate and to demonstrate that while the wind pressure strongly influences the lower walls airflow rate, it does not affect the higher walls performance. The exposure of the wall causes only a slight shift in the onset of the stack effect. The Reynolds number was calculated and the different air flow conditions in the ventilation channel were identified. Linear relationship between the external air temperature and air temperature in the gap were identified for each studied wall. The qualitative comparison with ventilated façades characterised by a massive clay cladding showed that the cladding's inertia influences the time in which the stack effect becomes more effective: during the night for low inertia claddings and during the daytime for massive ones.