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![Figure 2 [2]. Diminishing Rate of Return of Spandrel Section with...](profile/Lawrence-Carbary-2/publication/289355430/figure/fig9/AS:668522074087439@1536399491151/2-Diminishing-Rate-of-Return-of-Spandrel-Section-with-increased-insulation_Q320.jpg)
Increasing pressure to upgrade curtainwall thermal performance is occurring globally. The high vision areas and aluminium framing of typical commercial curtainwalls at a thermal disadvantage compared to other construction types. This has resulted in the engineering and design of highly insulating spandrel sections of the curtainwalls to improve on...
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... More recently, it has become associated with the conceptualization of the envelope as an intelligent environmental system [16]. The distinction between skin and façade is that the architectural façade is the public face of architecture, which communicates a specific message, whereas the "skin" is more of an all-enclosing system, an integral part of a building or a space [34]. On the other hand, the main difference between the skin and the curtain wall is that while the latter is always made of glass, the former can be made with other materials and is not necessarily hung. ...
The architectural façade has been a site of intensive experimentation and innovation throughout the 20th century, something that continues to this day, resulting in a vast range of architectural imagery, often incohesive in the post-modern reality. This research explores contemporary façade types and classifies the character of exterior building surfaces. In this paper, we aim to explore how the façade has been designed and has affected its surroundings. How and why has the façade evolved in the ways that it has? Is it the material innovation, structural novelty, the new design techniques or new aesthetics? We adopt a method of analytical induction to extract the most prevalent façade themes from relevant contemporary literature, characterize their meanings and categorize them in order to better explain the many sides of the façade. We set out to define the principles of façade design to then develop a general categorization, which can be applied to most building façades in recent history.
... The spandrel area (gap between edge of the slab and the cladding frame) is usually lined with a perimeter firestop system to prevent the internal spread of smoke and fire (See Figures 2 and 3 for a schematic showing these details in the context of the current study). The spandrel area, being important from a vertical fire spread perspective, is also insulated from the inside, typically using a mineral wool system [1,2]. ...
Facade systems used in modern buildings have received much attention in recent times due to their involvement in the propagation of fires in various incidents. These systems comprise of multiple components—cladding frame (typically of aluminum), façade panels (glass, aluminum composite panels, etc.), perimeter firestop (to seal the gap between floor and façade) and spandrel fire protection (typically provided from the inside of a compartment). While many standardized testing methods exist for quantifying their fire performance, most of them consider the behavior of individual components in isolation. The test conditions are also quite different from those encountered in real fire scenarios. The current study highlights these gaps and provides inferences from six full-scale real fire experiments conducted in a three-storey structure with different façade (curtain wall) and firestop configurations. Combustible façade panels of aluminum composite panels (ACP) and medium density fiberboard (MDF) and non-combustible glass panels of single glazed units and double-glazed units were utilized whereas two different methods of edge of the slab firestop and spandrel insulation were employed. The fire scenarios were developed at all floor levels (fire loads as well as initial ventilation conditions) as per realistic residential/office type dwellings. It was found that once the flames leap out of the fire compartment due to the failure of the façade panels, the spandrel area was subjected to 31 kW/m2 of additional heat flux, which indicated the need to consider fire protection of the spandrel area from the outside, especially for combustible façade systems. Further, one of the firestop installation methods was found to be more robust to address site tolerances and installation uncertainties arising due to workmanship as it allowed significantly less ingress of hot gases and toxic fumes to the upper floors. In terms of the two combustible panels, ACP and MDF, it was found that there were differences in their performance in a bench-scale experiment (cone calorimeter) and the full-scale experiments. MDF was found to perform better in the full-scale experiments. The method used for securement of the façade panels (pressure tape/silicone sealant and screws) was also found to have significant effect on the overall performance of the façade system; the failure mechanism of the façade panels was found to be different in both cases. It is expected that the findings presented in this study will provide insights to the real performance of different façade components as a system and will help in improving the codes and standards in the future.
... Insulated spandrel helps to curtail convective heat fluxes. The insulation also acts as a fire-stopping material at the edge of the floor slab [20]. However, topics on insulated spandrel sections are marginally considered in the literature [21,22]. ...
... Even with a thermally broken aluminum frame and a triple glazing Insulated spandrel helps to curtail convective heat fluxes. The insulation also acts as a fire-stopping material at the edge of the floor slab [20]. However, topics on insulated spandrel sections are marginally considered in the literature [21,22]. ...
... For instance, the typical curtain wall shown in Figure 1 utilized 100 mm thick mineral wool insulation. Even with a thermally broken aluminum frame and a triple glazing system, center-of-glazing and spandrel U-values of 1 W/m 2 K and 0.89 W/m 2 K were estimated for the system, respectively [20], which were very far from the requirements defined in energy codes like ASHRAE 90.1. Generally, most opaque insulated spandrels do not satisfy the prescriptive insulation values or effective U-values for cold climates [35]. ...
Almost every major city’s skyline is known for high-rise iconic buildings with some level of curtain wall system (CWS) installed. Although complex, a CWS can be designed for energy efficiency by integrating insulated spandrel components in space-constrained areas, such as slabs/plenums. The main aim of this study was to experimentally examine the thermal performance of an optimized curtain wall spandrel system integrated with vacuum insulation panel (VIP) as spandrel insulation. The study is based on robust experimental evaluations, augmented with appropriate numerical computations. The main study is constituted of six parts: (1) evaluation of VIP specifications and thermal properties; (2) analysis of VIP spandrel configuration, fabrication, and installation in a test building facility; (3) thermal bridge characterization of VIP spandrels; (4) monitoring and assessment of VIP durability within the spandrel cavities; (5) thermal performance analysis; and (6) assessment of related limitations and challenges, along with some further reflections. In all, 22 VIPs (each of size 600 mm2) were used. The effective thermal conductivity of VIPs ranged from 5.1–5.4 (10−3 W/mK) and the average value for initial inner pressure was approximately 4.3–5.9 mbar. Three VIP spandrel cases were fabricated and tested. The results proved that the Case 3 VIP spandrel configuration (composed of a double-layer VIP) was the most improved alternative for integrating VIPs.
... To further understand and improve CWS with integrated VIP spandrels (CWS-VIP sp.), some studies have focused on condensation risk, U -value and thermal resistance ( R -value) evaluations, and structural performance issues based on experimental and numerical methods [53,56,57] . However, during the thermal performance assessments discrete thermal bridges due to component VIP were either simplified or not reported in detail, thus the actual insulation performance will be of some magnitude inferior to expected outcomes. ...
... Firstly, Physibel TRISCO (v.13 w) was used to model and examine the performance of a VIP spandrel measuring 1500 mm × 1500 mm × 50 mm, according to ISO 10211. To validate the model, simulation results were compared to experimental results carried out with a hot box apparatus in compliance to ASTM C1363 [57] . TRISCO is a thermal analysis program for steady state heat transfer in three-dimensional objects consisting of different materials and submitted to different boundary conditions, using finite difference method [60] . ...
The thermal and energy performance of curtain wall façades can be improved by incorporating spandrel units in areas such as slabs/plenums to hide existing building services or areas where concealment of in- door space is required. The main objective of this study was to numerically investigate the performance of curtain wall façade with integrated vacuum insulation panel (VIP) as spandrel insulation. The main study constitutes six parts: (1) concept and derivation of governing equations, (2) model and its validation, (3) VIP integration alternatives, (4) overall thermal performance considering 2D/3D thermal bridges and internal surface temperatures, (5) building energy and vision-spandrel ratio effect, and (6) limita- tions and challenges. Thermal behavior of the system was characterized via 3D heat transfer simulations using Physibel TRISCO according to EN ISO 10211, while dynamic building energy analysis was carried out using EnergyPlus based on a stereotypical office building unit, in relation to the humid continental climate of Incheon, Republic of Korea. The baseline model was validated with experimental data from previous study, and a marginal discrepancy less than 4% was found between them. Further, the validated model was developed into different spandrel configurations, seeking to mitigate thermal bridges while improving insulation performance, by varying VIP integration design. Results indicated that the best VIP spandrel alternative improved thermal performance of the system by about 30%. Moreover, year-round space heating and cooling energy reductions were realized by gradually increasing the spandrel area by ratio from 0% to 80%, howbeit at the expense of electrical lighting energy. Finally, some noteworthy limitations of the study and challenges related to VIP integration into curtain wall spandrel have been duly discussed.
... It may not be uncommon to decrease the WWR to 61% by reducing the glass height to 2438mm (8 ft) and increasing the height of the shadow box to 1524mm (5 ft). Opaque assemblies of 1524mm x 1524mm (5 ft x 5 ft) have been studied and modeled previously [8][9] in this same spirit, however the assemblies studied were not shadow box designs. Given the history, the constraints of the test apparatus and the typical dimensions used in the industry today, the team of authors determined three assemblies would be used, as noted as Test A, Test B and Test C. ...
... ther or not including the adjacent vision sections has a meaningful impact on the test outcome. Test C is a shadow box assembly with dimensions of 1524mm x 1524mm (5 ft x 5 ft). Aside from the increase in height this sample is identical to Test B previously described. The purpose of this sample was for comparison with the outcome of previous tests. [8][9] 2.2 Options 1, 2, 3 & 4 – Variations on the Shadow Box Insulation Furthermore, four insulation configurations were tested in framing systems A, B & C and will be furthermore referred to as insulation options 1, 2, 3, and 4. These assemblies are highlighted inFigure 2.3. On the left hand side of the figure the insulation panels are sh ...
... s show that the accuracy of the simulation does indeed depend on the physical configuration of the test sample (A-C) and insulation (1-4) chosen. Furthermore, they suggest that the level of error in the simulation increases with the actual R-value of the sample evaluated. This has been recently reported in non-shadowbox curtain wall spandrel cases. [8][9] Another metric by which the accuracy of the U-factors determined can be evaluated is gained by observing the equivalency criteria dictated by the NFRC 100 standard. The most recent version identifies that numerical modeling and test equivalency are established by the standard when the simulated U-factor is within 10% of the tested va ...
Research was performed to establish the merits of utilizing fumed silica vacuum insulation panels (VIP) and aerogel enhanced fabrics in the construction of curtain wall spandrel areas; specifically, with the aim of considering potential performance improvements and novel esthetic possibilities. In doing so, a thermally isolated framing system adapted from plans for a commissioned building was chosen as a benchmark and detailed according to conventional practices commonly employed for unitized curtain wall construction. Spandrel assemblies incorporating this framing system with various applications of insulating materials were evaluated by the FEM (finite element method) and compared to results obtained from experimental evaluation. Respectively the software program Therm 6.3[1] and the ASTM C 1363[2] procedure were used with NFRC100 [3] environmental conditions. With regard to geometry, two unique compositions were employed for the study consisting of both a spandrel area isolated from adjacent vision areas and spandrel area with adjacent vision areas above and below the spandrel. In the latter case, both a fixed head rail and stack joint were included. The physical dimensions of the samples varied from 900mm x 1500mm to 1500mm x 2130mm (3 ft x 5 ft to 5 ft x 7 ft). The results of the work established that thermal modeling techniques can be proven to predict spandrel area thermal transmittance with reasonable accuracy when compared to an accepted industry test standard. Furthermore, the merits of the innovating the insulation technologies proposed are addressed quantitatively and the results are projected for a range of typical curtain wall assemblies.
Curtain wall façades have been embraced worldwide as a key sign of modern architecture. To improve the thermal characteristics and energy performance of curtain wall systems (CWS), insulated spandrels are installed between glazing sections. However, there are some noteworthy space-technical constraints. Firstly, CWS are structurally supported by frame systems. The inner length (interior projection) of a curtain wall frame is related to its structural requirements. When high structural performance is not needed, inner length is usually shortened. However, the inner length also creates space for insulation. Due to this space problem, even when high structural performance is not required, the inner length is still enlarged to accommodate the required thickness of insulation. Also, spandrel sections with thick insulated back panels are conventionally installed behind monolithic glazing or opaque claddings between slab/plenum areas of adjacent floors and hidden from the view of building users. Otherwise, aesthetics is compromised due to protrusions. Thus, total area to install insulation in curtain wall façades is traditionally defined and limited to slab/plenum areas only. Consequently, there could be undesirable increase or decrease of window-to-wall ratio as well as restriction of design freedom. Such slim façades require thin and high-performance insulation solutions. Among super-insulating materials currently available, vacuum insulation panel (VIP) is a good go-to insulator to be integrated into curtain wall spandrels. This study seeks to present a comprehensive review on CWS integrated with VIP as spandrel insulation. Depending on the level of prefabrication and how they are built, CWS can broadly be categorized into stick, unitized, and structural glazing systems. Curtain walls differ significantly from conventional windows in that curtain walls are anchored from floor slabs of a building (hangs like a curtain) whereas windows are mounted between floor slabs. Throughout literature, VIP integrated into CWS is composed of fumed silica core material and encapsulated in a metalized laminate (Si-VIP). Under severe accelerated aging conditions, studies proved that VIP spandrel modules provided ten times protection to the VIPs as compared to standalone VIPs. The concept represents a strategy to extend the service life and in-service durability of VIPs, while improving the energy consumption footprint of CWS. As far as the authors know, this paper is the first state-of-the-art review covering CWS integrated with VIP spandrels. Finally, current challenges and future research opportunities concerning VIP integration in CWS are explored.
