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Double Skin Facades (DSF) are regaining popularity as a way to increase the climate resilience of buildings. Building Performance Simulation (BPS) is commonly used for their assessment, but modelling DSFs with BPS is challenging due to their complex thermophysical behaviour. Several research works have evaluated the capabilities and limitations of BPS for modelling specific DSF configurations. This work presents a validation study based on experimental data from a full-scale naturally ventilated double-skin façade, compared against results from the BPS software IDA-ICE. The study found that in periods with low solar irradiation, the different modelling strategies had a minor influence on the results, with a high agreement between measurements and simulation. In contrast, periods with solar irradiation showed a higher sensitivity to the modelling strategy, with more significant deviations from the measurement results.

Double-skin facades’ application has positive and negative effects on the building’s behaviour and performance. However, there is an ongoing debate about the advantages and disadvantages of DSF due to the lack of reliable data on DSF’s actual performance. This paper aims to present the advantages and disadvantages of the DSF by reviewing previous studies investigating the benefits and limitations of using the DSF system based on the parameters, namely, the DSF components and types. A general agreement is found that the application of DSF’s appropriate design positively affects building performance or the environment, despite the consensus on the high maintenance and construction costs of this DSF system compared to the single-skin façade (SSF).

Natural daylighting is a key indicator of how occupants are satisfied with their visual environment. Modern architectural facade designs are often characterized by ample transparent surfaces, thus an indeliberate design could encounter daylighting deficits or surplus. In Egypt, southern facades are over lit almost all year-round, and utilizing perforated double skin facades is one design strategy that helps achieve occupant’s visual comfort, only if subtly designed and allocated. There have been several studies on the daylighting performance of perforated double skin facades, but only few have considered the design of their shape or perforation ratio, especially in Egypt. This paper aims to optimize the daylighting performance of perforated screens in office buildings in Egypt. For doing so, the study uses parametric design techniques to define the optimum perforation shape and ratio of a non-uniformly perforated screen of an office space, in Cairo. Performance metrics are the task plane illuminance and daylighting distribution, calculated on each solstice/equinox during three occupancy points in time. The results show that a total perforation ratio (PR) of 30% of rectangular shapes, most perforated around the fringes than the centre, achieve the optimal daylighting distribution of up to 83% in all seasons. Circular and triangular shapes with a PR of 27.5 and 26.2%, respectively, achieve a daylighting distribution of 85 and 75%, only in certain seasons.

We present large-eddy simulation (LES) of flow past different airfoils with $Re_{c}$ , based on the free-stream velocity and airfoil chord length, ranging from $10^{4}$ to $2.1\\times 10^{6}$ . To avoid the challenging resolution requirements of the near-wall region, we develop a virtual wall model in generalized curvilinear coordinates and incorporate the non-equilibrium effects via proper treatment of the momentum equations. It is demonstrated that the wall model dynamically captures the instantaneous skin-friction vector field on arbitrary curved surfaces at the resolved scale. By combining the present wall model with the stretched-vortex subgrid-scale model, we apply the wall-modelled LES approach to three different airfoil cases, spanning different geometrical parameters, different attack angles and low to high $Re_{c}$ . The numerical results are verified with direct numerical simulation (DNS) at low $Re_{c}$ , and validated with experiment data at higher $Re_{c}$ , including typical aerodynamic properties such as pressure coefficient distributions, velocity components and also more challenging measurements such as skin-friction coefficient and Reynolds stresses. All comparisons show reasonable agreement, providing a measure of validity that enables us to further probe simulation results into aspects of flow physics that are not available from experiments. Two techniques to quantify hitherto unexplored physics of flows past airfoils are employed: one is the construction of the anisotropy invariant map, and the second is skin-friction portraits with emphasis on flow transition and unsteady separation along the airfoil surface. The anisotropy maps for all three $Re_{c}$ cases, show clearly that a portion of the flow field is aligned along the axisymmetric expansion line, corresponding to the turbulent boundary layer log-law behaviour and the appearance of turbulent transition. The instantaneous skin-friction portraits reveal a monotonic shrinking of the near wall structure scale. At $Re_{c}=10^{4}$ , the interaction between the primary separation bubble and the secondary separation bubble contributes to turbulent transition, similar to the case of flow past a cylinder. At higher $Re_{c}=10^{5}$ , the primary separation breaks into several small separation bubbles. At even higher $Re_{c}=2.1\\times 10^{6}$ , near the turbulent separation, the skin-friction lines show small-scale reversal flows that are similar to those observed in DNS of the flat plate turbulent separation. A notable feature of turbulent separation in flow past an airfoil is the appearance of turbulence structures and small-scale reversal flows in the spanwise direction due to the vortex shedding behaviour.

This study used a genetic algorithms research methodology to examine various design parameters for attaining a balance between daylight availability and visual comfort in educational facilities utilizing a double skin facade (DSF) inspired from mashrabiya. This encompasses its perforation ratio, depth, gap width from the external wall and inclination angels. The research pertains to the protocols and performance indicators of the most recent Leadership in Energy and Environmental Design system. Simulations of point-in-time illumination (PIT) were conducted. Results have shown that the preferred perforation ratios are: - (70%) in summer and (50%) at winter. preferred inclination angels: - (From 75:120 degrees at 9AM, From 15:135 degrees at 3PM, From 75:120 degrees at 3PM) at summer, (135 degrees at 9AM, From 105 to 135 at 12 PM, 135 degrees at 3PM) at winter.

Energy used in buildings is mainly attributed to provide the desired thermal comfort, which could result in an increase in carbon emission and, in turn, lead to further environmental degradation. A Building-Integrated Photovoltaic Double-Skin Façade (BIPV-DSF) is a promising way to maintain indoor thermal comfort, obtained with low environmental impact and energy consumption. The appropriate design of BIPV-DSFs can maximise indoor thermal comfort and energy efficiency for buildings. This paper presents optimal BIPV-DSF design solutions, which are dedicated to offering comfortable and energy-efficient buildings, through optimisation of the most important design parameters of a BIPV-DSF under three different climate conditions in Australia. The results illustrate how thermal transmittance (U-value) and solar heat gain coefficient (SHGC) of windows of the BIPV-DSF, as the most important design parameters, were optimised for application in the context of different climates, operation modes, and orientations. The paper contributes to the matters concerning the integrated effect of BIPV-DSFs on thermal comfort and energy performance in buildings.

The object of research is the thermal regime of a high-rise building (the Lakhta Center) equipped with modular double-skin facade structures with buffer zones. Method. A comprehensive approach was used, which included the development of a numerical model of the buffer zone and conducting field observations with the use of an actinometric station for accurate measurement of solar radiation parameters. Results. It was shown that solar radiation has a substantial impact on the building's thermal regime in the summer. The maximum recorded temperature in the buffer zone reached +54°C. The obtained results confirm the significant contribution of solar radiation to the heat and mass transfer processes within the buffer zone of a skyscraper with a transparent facade.

Collagen is the main structural element of connective tissues, and its favorable properties make it an ideal biomaterial for regenerative medicine. In dental medicine, collagen barrier membranes fabricated from naturally occurring tissues are used for guided bone regeneration. Since the morphological characteristics of collagen membranes play a crucial role in their mechanical properties and affect the cellular behavior at the defect site, in-depth knowledge of the structure is key. As a base for the development of novel collagen membranes, an extensive morphological analysis of four porcine membranes, including centrum tendineum, pericardium, plica venae cavae and small intestinal submucosa, was performed. Native membranes were analyzed in terms of their thickness. Second harmonic generation and two-photon excitation microscopy of the native membranes showed the 3D architecture of the collagen and elastic fibers, as well as a volumetric index of these two membrane components. The surface morphology, fiber arrangement, collagen fibril diameter and D-periodicity of decellularized membranes were investigated by scanning electron microscopy. All the membrane types showed significant differences in thickness. In general, undulating collagen fibers were arranged in stacked layers, which were parallel to the membrane surface. Multiphoton microscopy revealed a conspicuous superficial elastic fiber network, while the elastin content in deeper layers varied. The elastin/collagen volumetric index was very similar in the investigated membranes and indicated that the collagen content was clearly higher than the elastin content. The surface of both the pericardium and plica venae cavae and the cranial surface of the centrum tendineum revealed a smooth, tightly arranged and crumpled morphology. On the caudal face of the centrum tendineum, a compact collagen arrangement was interrupted by clusters of circular discontinuities. In contrast, both surfaces of the small intestinal submucosa were fibrous, fuzzy and irregular. All the membranes consisted of largely uniform fibrils displaying the characteristic D-banding. This study reveals similarities and relevant differences among the investigated porcine membranes, suggesting that each membrane represents a unique biomaterial suitable for specific applications.

Double skin facades (DSF) are an architectural feature of buildings that can be part of the next steps in the development and application of sustainable development strategies. The integration of innovative elements into DSFs can provide more efficient use of renewable energy sources or reduce operating costs. The vast number of studies that address this topic require systematic categorization and review of the conclusions of these works. In this work, an analysis of the literature focusing on DSFs has been performed. The aim was to categorize the conclusions of the works into categories that define the current research topics. The literature review shows that energy efficiency, daylighting, use of shading devices and vegetation are currently the most relevant topics. However, the review also shows that little attention has been paid to the interaction between these topics.

Vertical building enclosures known as Double-skin façades (DSFs) have become recognized as a promising façade type for buildings that place emphasis on sustainable, green, and energy-efficient design performance. DSFs are highly integrated across engineering and architecture; however, there remain limited centralized knowledge repositories that offer designers’ insight into these performance trends, multi-disciplinary collaboration, and tradeoff metrics, as well as how to go about modeling DSFs for performance under applicable loading systems when conducting design. As such, the main objective of this paper is to provide a better understanding of different types of DSF systems and their attributes from the perspective of multiple disciplines, as well as different modeling approaches. The methodology adopted is rooted in the principles of systematic literature review of design standards, research papers, and software manual literature, as well as a qualitative evaluation based on structural performance aspects. From the study, many different configurations of DSFs exist that impact each engineered system, where those system attributes impact multiple systems. This results in a need to parametrically iterate configurations within software to find a balance in DSF performance. Furthermore, there exists software easily capable of simulating these systems, yet the designer must carefully construct the models with different levels of sophistication towards DSFs and the software. This paper contains concise summaries of key attributes that designers need to consider when their project has a DSF system, along with different software modelers from which they can choose, correlating to the complexity of the design stage along with the appropriateness of the calculations.