Summer thermal performance analysis of an Opaque ventilated Façade operating under the dynamic insulation principle

Abstract

Opaque Ventilated Facades (OVFs) have gained significant scientific interest over the last decades, as the requirement for buildings to adapt to their environment is increasingly becoming more important. However, the continuous increase of the envelope thermal resistance, despite the undoubtable contribution in the building’s energy efficiency during the heating season, may raise a penalty during the warm period of the year, which in term gains a continuously increasing importance due to climate change. Dynamic insulation concept on the other hand is based on the idea of on-demand modifying the thermal resistance of the envelope significantly, allowing the building to take advantage of the environmental conditions on an annual, if not on a diurnal basis. In this study, the OVF technology is combined with the dynamic insulation concept in a naturally ventilated OVF configuration where the ambient air can surpass the insulation layer to decrease its effect and to enhance heat loss whenever this could relieve the building envelope from daytime’s thermal stress. A detailed thermal analysis was conducted for the summer climatic conditions of the Mediterranean area and the efficiency of the system in passively extracting stored heat was assessed for four different wall assemblies. The results revealed an efficiency 2.1–2.6 times higher than a conventional OVF’ s in removing heat, with the maximum one observed when the thermal mass was equally split in the two cavity sides. A qualitative comparison of the system’s performance with conventional OVF solutions and other adaptive façade systems was also conducted revealing the current system’s advantages.