Thermal and energy performance investigation of a smart double skin facade integrating vanadium dioxide through CFD simulations

Abstract

Double skin facades (DSFs) are known by their capacity to generate a natural heating energy during winter by increasing the greenhouse effect in the air cavity between the inner and the outer facade. However, this effect provides an undesirable overheating during summer. In this study, a smart DSF configuration able to control the greenhouse effect generation was numerically simulated using a two dimensional Computational Fluid Dynamic (CFD) method. The aim of these simulations is to investigate the thermal and the energetic behavior of a DSF integrating Tungsten (W) doped Vanadium dioxide (VO2) as an optically smart thin material and a high absorbing aluminum nitride (AlN) coating. A parametric study was carried out in order to analyze the impact of the air cavity thickness on the smart DSF behavior. Four thicknesses (10, 25, 50 and 75 mm) were inspected and compared with an uninsulated massive wall configuration. Results have shown that the smart configuration reduces significantly both heating and cooling loads. Indoor surface temperature has been decreased by around 2 °C during summer and increased by around 3 °C during a sunny winter day. The air velocity results have shown that the natural convection-radiation interaction during winter is higher than during summer. Thus, the new smart DSF configuration presented in this paper can effectively control the greenhouse effect depending on external climatic conditions.