Analytical assessment of thermal performance of a ventilated glazed facade system

This paper outlines a methodology for determining the thermal performance of a complex ventilated glazed facade system through desktop analysis and computer simulation.There is a limited amount of published work on the overall thermal performance values of complex doubled skin facades with a ventilated cavity between the facade layers. A well designed double skin facade should significantly improve the thermal performance of the overall construction as the heat build up within the cavity can be dissipated through stack effects and natural ventilation.The ISO 15099:2003 [1] standard provides a detailed calculation methodology for determining the thermal properties of complex glazing systems, including those with a ventilated cavity. A study has been undertaken of a particular assembly proposed for a commercial building in Brisbane. The study has used the ISO 15099 approach to determine the thermal properties of the glazing system. The assembly has also been modelled through dynamic thermal modelling and computational fluid dynamics (CFD) to compare its performance to the analytically derived solution using the ISO standard. The results show that there is good agreement between the analytical solution and the numerical analysis and that the approach presented herein can be used for determining the thermal performance of these types of facades where no manufacturer data exists.