Experimental Comparison Between Three Types of Opaque Ventilated Facades

Background: The growing interest for the energy efficiency of building technologies has led the construction sector towards the adoption of Opaque Ventilated Facades (OVFs) as high-performance solutions for building systems. Objective: The aim of this study is to determine the optimal thermal inertia of the outer surface of ventilated facades with respect to the indoor comfort and the reduction of the outdoor overheating. Method: An experimental study was carried out in Central Italy (Mediterranean climate), by comparing the thermo-physical performance of three opaque ventilated façades, characterized by different positions of the mass (hollow bricks) within the air cavity. One has no mass and is enclosed by a Lightweight (L) cladding; one has an Internal Mass (IM) right adjacent to the insulation layer and an external lightweight cladding; the last one has an External Massive cladding (EM). The three prototypes (L, IM and EM walls), were installed on a test room and simultaneously monitored in the summer season. Result: The experimental outcomes demonstrate that the EM wall outperforms the others in terms of cooling efficiency, as the incoming heat fluxes towards the indoors are considerably reduced. Moreover, such a configuration led to the lowest surface temperatures on the outer slab, thus contributing to the mitigation of the external environmental overheating. Conclusion: Overall the External Mass (EM) solution was found to be the best choice, being beneficial for mitigating the outdoor surrounding temperatures and enhancing the buoyancy-driven ventilation.