An experimental sensitivity analysis on the summer thermal performance of an Opaque Ventilated Façade

In the last few years opaque ventilated façades (OVFs) have reached an increasing diffusion in theMediterranean area for their capability of reducing the heat flux across the building envelope in summerconditions as well as preventing the condensation and infiltration risk in the winter period providingwind and rain protection, thus increasing the durability of the façade. Moreover, the possibility to hostdifferent cladding allows architects to explore a wide range of façade combinations. In the frameworkof a regional funded project, an extensive in-field experimental campaign was carried out in the summerperiod on different full-scale OVF configurations, with the aim of assessing the thermal performance of anewly developed OVF based on hollow clay claddings technology.A sensitivity analysis was thus performed, in order to evaluate, on the one hand, the effect on the per-formance of the main façade features, e.g. ventilation channel height, solar absorption coefficient andventilation grills openings ratio, and on the other hand, the influence of the outdoor boundary conditions,e.g. solar radiation and external air temperature.The experimental results highlight that the façade configuration and the design features significantlyaffect the capability of OVFs on minimising the solar heat loads across the wall (between~30%and~70%) if compared to an unventilated façade (representing the reference configuration). These resultsallow providing general guidelines for an optimised OVF design. Moreover, the assessment of the effect ofthe outdoor boundary conditions allowed to identify the conditions in which the façade shows the higherexploitation of natural ventilation.