Experimental analysis of the summer thermal performances of a naturally ventilated rainscreen façade building

In this paper the thermal behaviour of rainscreen ventilated façades under typical Mediterranean summer weather conditions has been investigated experimentally by using a large-scale test building located at San Mauro Pascoli (Italy). The main goal of this work was to quantify the reduction of the heat flux across the inner wall due to the enthalpy discharge linked to the airflow established within the cavity of the ventilated wall during a typical summer day. The experimental results highlight that the heat flux reduction is strongly correlated to the exterior finish of the rainscreen, to the presence of open joints and ventilation grills and to the air cavity thickness of the façade. In order to study the impact of these different aspects on the thermal performances of the ventilated walls, ten different configurations for the ventilated façade have been investigated. The experimental results highlight that the feature of the ventilated wall to reduce the summer loads depends on the capacity of the system to limit the value of the temperature within the cavity and this can be obtained by reducing the pressure losses along the cavity in order to increase the air flow rate and by minimizing the long-wave radiative contribution within the cavity.