The Interaction of Wind Velocity and Air Gap Width on the Thermal Comfort in Naturally Ventilated Buildings with Multiple Skin Facade

Abstract

A Multiple (MSF) or Double Skin Facade (DSF) is a building envelope system. It has an external and internal layer that contains buffer space used for controlled windy conditions, ventilation and solar protection. Employing a multiple or double-skin facade for natural ventilation is not an innovative idea, but the background on this mechanism and the impacts of these environmental and designing factors on its performance are still unknown and critically needed. Therefore, with this study, the influences of the Multiple or Double Skin Facade with different width air gaps configurations, alongside the environmental factor on buoyant-driven natural ventilation, are discussed. Naturally ventilated MSFs are often very intriguing in terms of a microclimatic comfort, but an optimum design is crucial to enhance the microclimatic comfort and therefore the proper operation of the entire system. Especially, the development of the system is important when working in a hot climate. There is a significant lack of data within the current literature to demonstrate the complexity and challenges in designing large, naturally ventilated buildings. For these sorts of buildings, it is important to possess the tools to gauge a design’s predicted performance to realize successful natural ventilation concepts. However, with the utilization of glass, heat loss during the winter and solar gain during the summer will increase energy loads. At the same time, this will also negatively effect the microclimatic comfort. Through this study, both the effect of the utilization of multiple facades on indoor comfort conditions and thus the effects of distances at different distances from the facade on wind flow and therefore microclimatic comfort at the situation of the Multiple Skin Facades were investigated. This paper demonstrates through a sensitivity analysis, an optimal strategy for completing a CFD simulation of this special building envelope. This study also attempts to research a mechanically ventilated building with DSF configuration—a building in terms of indoor microclimatic thermal comfort. The aim of this study is to work out the effect of wind velocity and wind distribution on naturally ventilated buildings with DSF configuration, to work out if a DSF configuration will provide a far better microclimatic thermal comfort through natural ventilation. This study not only defines and analyzes the dimensional parameters of the air gap to maximize airflows, but also explores the importance of design decisions on system performance, such as the interaction between thermal mass and air gap distances and the building facade. Keywords: double skin facade, microclimatic thermal performance, airflow modelling, ındoor microclimatic thermal comfort, wind velocity, wind distribution, CFD, natural ventilation performance simulation