Composite polymeric materials as an alternative to aluminium for improved energy performance of ventilated façade systems

Ventilated façade systems have become an interesting solution in the field of energy efficiency for buildings thanks to their associated improvement in thermal insulation properties. However, differences exist between real and theoretical thermal performance, resulting in an increase of actual energy consumption above predicted values. Part of this mismatch can be attributed to thermal bridges both at support elements and at construction junctions, which are usually overlooked by simplified calculations. The present study assesses the potential for substituting metallic elements with polymeric composite materials for two key elements of ventilated façades: the support subframe of the external cladding and the external window reveals. Thermal, structural and durability properties are specifically assessed. Results show that overall heating energy savings between 7 and 13% can be obtained through the use of pultruded composite profiles at support brackets and window reveals instead of aluminium components. Such solutions are feasible from a mechanical and durability point of view, and the extra costs are offset in a short period through the reduction in heating expenses.