Naturally Ventilated Double Skin Façades: Comparisons Between Different CFD Models

Double Skin Façades (DSFs) have become widespread solutions commonly employed in new and existing buildings in the last decades. Since its introduction, the multi-layered façade has improved profoundly, assuming more articulate and complex shapes for better energy performances and combining advanced technologies as innovative materials or systems. However, the effectiveness and the thermal behaviour of DSFs should be carefully evaluated since the design phase by selecting proper methodologies, thus avoiding inaccurate results. In fact, the correct estimation of the airflows inside DSF channels is heavily influenced by the simulation settings. Furthermore, the lack of measurements or empirical validations in the field is the primary source of concern for researchers. Considering the available numerical methods for investigating DSFs, Computational Fluid Dynamics (CFD) simulations have proven to be the most appropriate option. The present work compares multiple Double Skin Façade configurations by performing CFD analyses and adopting different turbulence models in bi- and three-dimensional domains. The results underline the capability of 2D models in predicting the fluxes inside the DSF channel and in the domain. Furthermore, comparisons among the velocity profiles estimated by adopting different turbulence formulations highlight only slight variations, especially in proximity to the perturbated areas of the cavity.

Application of physical theory of cavity in the construction of double skin facades

The article deals with the issue of double skin transparent facades as a new technological-operational system of transparent exterior walls. Especially of high-rise buildings, which with its operating modes ingeniously uses a renewable source of solar energy to reduce the energy needs of the building. The basic precondition for the correct function of the double skin facade is its functional aerodynamics in any climatic conditions of the outdoor climate. In the critical state of windlessness, the aerodynamic quantification of a double skin facade is the total aerodynamic resistance of the cavity, which consists of the aerodynamic frictional resistances along the length of the air flow line and local aerodynamic resistances of the cavity. The article analyses the functional aerodynamics on two frequented types of double skin facades with a narrow type and corridor type cavity. At the end it confronts functional aerodynamics with the results of their temperature, aerodynamic and energy regime obtained from in-situ experiments.

Calibration of DSF model for real-time control

Double Skin Façades are complex fenestration systems capable to control solar heat gain and ventilation in buildings. Due to the high flexibility of such innovative components, having energy models able to replicate the thermal behaviour of the Double Skin Facades is of utmost importance for their optimal control and integration with building automation strategies. In this context, a numerical model has been developed and validate within the experimental data. The methodological steps are presented in this work and in the last section, the potential applications of the model are discussed.

A Method of Reducing the Distorting Curvature of Insulated Glass Units Due to Partial Rarefaction in Interglass Space

Currently, insulated glass units (hereinafter abbreviated as IGU) are the main type of translucent filling used in curtain walls. Under the influence of climatic loads in IGU, the thickness of the inter-glass space changes, leading to the deformation of the glasses. Deformations of glass lead to optical distortions on curtain walls. The paper considers the technical solutions used in the existing engineering practice to reduce the distorting curvature of IGU: the use of more rigid external glasses as part of IGU, the use of double-skin facades with external independent single glass, the use of vacuum IGUs. A new method is proposed to reduce the distorting curvature of IGUs by fixing the thickness of the interglass space. It is achieved by installing other point or linear supports between the panes. The introduction of other supports solves the problem of reducing deformations only when IGU is compressed. When the interglass space is expanded, the supports are turned off from operation and the glass is freely deformed. Therefore, to avoid such deflections, it is necessary to pre-compress the IGU under a load equivalent to the climatic load on the IGUs operating in the construction area of the object. Calculations show that for the climatic conditions of the city of Moscow, the required degree of rarefaction the interglass spaces is only 5 % of the absolute atmospheric pressure.

CFD Modelling of Naturally Ventilated Double Skin Façades: Comparisons among 2D and 3D Models

Nowadays, Double Skin Façades (DSFs) are popular technologies adopted for both new and existing buildings. Since their introduction, new configurations and materials started to be tested to improve the DSF energy behaviour and function. Such complex technologies, able to improve comfort conditions of occupied spaces and decrease building energy requirement, are strictly related to the design phase that should be carefully evaluated. The correct prediction of air fluxes inside the DSF cavity, in fact, is highly influenced by the adopted analysis hypothesis and settings. Moreover, the absence of multiple experimental campaigns and empirical validations in the sector represents the major concerns for scientists and researchers. Among the possible numerical approaches for studying DSFs, Computational Fluid Dynamics (CFD) analyses confirm to be the most suitable solution. The CFD modelling activity presented in this paper intends to compare various Double Façade configurations by adopting bi- and three-dimensional domains and different turbulence models. According to the obtained results, 2D simulations can predict airflows inside and around the DSF channel with good approximation and reasonable computational effort. Moreover, the velocity profiles estimated by the turbulence formulations are in good accordance, underling only a few slight variations in proximity to the DSF layers.