Box Window Research Articles

Research on the Design Strategy of Double–Skin Facade in Cold and Frigid Regions—Using Xinjiang Public Buildings as an Example

In the context of global warming, the focus on applying and researching double–skin facade (DSF) systems to reduce energy consumption in buildings has significantly increased. However, researchers have not thoroughly examined the performance and applicability of DSFs in severe cold regions with high winter heating demands. This study aims to evaluate the potential application of DSFs in the harsh cold cities of Northwest China and investigate their role in enhancing energy efficiency in large public buildings. Through energy consumption simulation and a comprehensive evaluation using the TOPSIS entropy weight method, the effects of applying 20 DSF schemes in four cold cities in Xinjiang (Kashgar, Urumqi, Altay, and Turpan) were analyzed. The experimental results indicate that the average EUI energy–saving rates in Kashgar, Urumqi, Altay, and Turpan are 64.75%, 63.19%, 56.70%, and 49.41%, respectively. South–facing orientation is deemed optimal for DSF in Xinjiang cities, with the highest energy–saving rate reaching 15.19%. In Kashgar, the energy–saving benefits of west–facing DSF surpass those of north–facing DSF. Conversely, the order of orientation benefits for other cities is south, north, west, and east. An analysis of heating, cooling, and lighting energy consumption reveals that Box Windows exhibit superior heating energy efficiency, while Corridors are more effective for cooling. This characteristic is also evident in the optimal installation orientation of various types of curtain walls. Given the relatively higher demand for heating compared to cooling in urban areas, Box Windows yields significant benefits when facing south, west, or north; conversely, if there is a high demand for urban cooling, Corridors should be considered in these three directions. Multistorey DSF systems are suitable for east–facing buildings in Xinjiang cities. Selecting suitable DSF schemes based on specific conditions and requirements can reduce building energy consumption. The research findings offer theoretical guidance for designing and implementing DSF in diverse cities in cold regions.

Over-Size Pill-Box Window for Sub-Terahertz Vacuum Electronic Devices

The pill-box window is one of the important components of microwave vacuum electronic devices (VEDs), and research into it is of great significance. As the operating frequency increases, the problems associated with the reduction in the structure size include the reduction of the brazing plane and the reduction in the tolerance of the pill-box window. These problems will cause traditional pill-box windows to be unsuitable in high-frequency bands, especially in terahertz and sub-terahertz regions. The most influential factor is the length of the circular waveguide in the box window. The welding plane of the over-size pill-box window is the annular bottom surface on both sides of the dielectric sheet, which is larger than the circular waveguide, and the operating frequency does not directly affect the area of the brazing surface. Choosing a suitable diameter for the dielectric sheet can effectively increase the tolerance to the length of the pill-box window circular waveguide. Therefore, an over-size pill-box window would be a practicable approach to improve the performance compared to the traditional pillow-box in high-frequency bands. This paper describes, in detail, the theoretical design, simulation optimization and experimental process of this improved pill-box window. An over-size pill-box window suitable for G band VEDs was successfully developed. The experimental result in the 215–225 GHz band is that the maximum transmission loss is −1 dB, and the overall transmission loss is close to −0.5 dB. The overall reflection is less than −11 dB.

Investigation on Symmetric and Asymmetric Broadband Low-Loss W-Band Pillbox Windows

In order to develop wide-band low-loss windows for W-band vacuum electronic devices and easily fabricate them, symmetric and asymmetric pillbox windows are investigated and reported in this paper. A symmetric pillbox window and an asymmetric pillow-box window were designed, simulation optimized, fabricated, and tested. The initial parameters for the two pillbox windows were designed by equivalent circuit theory. Computer simulation technology (CST) three-dimensional (3D) electromagnetic simulation software was used to verify and optimize the design. Because of the uncontrollability of welding during the experiment, this article provides two solutions. One is to measure and reprocess the symmetrical pillbox window with the dielectric sheet welded to reduce the influence of welding on the measurement results; the other is an asymmetrical box window which is designed to avoid the error caused by the welding of the box window. The best experimental results for the symmetric pillbox window were |S21| close to 1 dB and reflection parameter |S11| close to 10 dB in the frequency range of 77–110 GHz. The experimental results for the asymmetric pillbox window were |S21| < 1 dB nearly in the frequency range of 76–109.5 GHz. The experimental results show that both solutions efficiently complete the design of broadband pillbox windows and would potentially be operated in the gigahertz millimeter-wave region.

Performance Investigation of OFDR Sensing System With a Wide Strain Measurement Range

Spectrum registration and spatial calibration are presented and demonstrated in optical frequency domain reflectometry based sensing system for achieving a wide strain measurement range. In both dynamic and static measurement case, the feasibility of the proposed method is evaluated. First, spectrum registration is demonstrated to demodulate strain value, which increases the data acquisition rate dozens of times and also keep the high measurement range. A measurement rate up to 800 Hz is achieved. Second, the general difficulty in large strain measurement is analyzed. The combination of spatial calibration and spectrum registration is, therefore, proposed to reduce the mismatch of the spatial segments in the case of large strain variation. The local measurement spectrum segment extracted by a narrow box window for spectrum registration is proposed to maintain a high spatial resolution. Strain exceeding 7000 μe is demodulated with a gauge length of 5 mm accurately. Finally, graphic processing unit (GPU) technology is used to accelerate the data processing rate in the demodulation process, which makes it more hopeful for the practical application.

Speed Up Bilateral Filtering via Sparse Approximation on a Learned Cosine Dictionary

The edge-preserving bilateral filter (BF) is a widely used smoothing tool in many applications. However, its brute-force implementation depends on the size of the box window. The shortcoming causes BF time-consuming for the image processing task with a large window. To make the computational complexity irrelevant to the window size, sparse approximations of the filtering kernels are calculated on a learned cosine dictionary by two steps. First, all possible frequencies are learned (estimated) from the filtering kernel to compose a cosine dictionary. Then, the sparse approximation is conducted on the learned dictionary to seek the optimal cosine approximation for both the range and spatial kernels. By making use of the one-dimensional cosine approximation for the range kernel, the BF is transformed into spatial convolutions. Subsequently, by employing the two-dimensional cosine approximation for the spatial kernel, spatial convolutions are decomposed into box filters of which the computational complexity is O(1). To the best of our knowledge, our approach is the first method that adaptively constructs a cosine dictionary according to the input kernel. This merit guarantees the best filtering accuracy and efficiency. These advantages are corroborated by several carefully designed experiments.

Improved Bilateral Texture Filtering with Edge-aware Measurement.

Texture filtering depends on high-quality texture measurement to separate structures from textures. However, the existing methods employ axis-aligned box windows for texture measurement, which may cover different texture regions, and so lowering the measurement quality because structure edges are not always parallel to the axes. Additionally, the existing texture measurements consider intensity contrast at the pixel level and do not account for the linear characteristics of structure edges in filtering windows; thus, their measurement effectiveness is limited. This results in a dilemma for texture filtering. Large-scale textures are not smoothed using smaller windows, while small structures are removed using larger windows. In this paper, we present edge-aware measures to improve texture measurement. Edge-aware windows are constructed such that each window is inside a texture region to the greatest extent possible, and the linear characteristics of structure edges are accounted for in the texture measurement. Furthermore, we use large box windows for texture filtering and long and narrow edge-aware small windows for texture measurement to filter out large-scale textures while preserving small structures. The experimental results show improved texture filtering with our method compared with existing methods.

Mechanically ventilated double-skin facade in a hot and humid climate: summer monitoring in an office tower in Tel Aviv

ABSTRACTDouble-skin facade (DSF) is regarded as one of the most advanced and promising curtain wall technologies currently available, adopted until recently mainly in cold and temperate climates. Despite their potential for improved thermal performance compared to conventional curtain wall technologies, experience with the application of DSF technology in hot climates is still little. This paper presents the results of the first DSF monitoring in Israel, executed in the first office building in Israel to apply this technology. Results show that the applied DSF technology (mechanically ventilated box window DSF with integrated blinds) has a potential for keeping indoor temperatures up to 2°C below outdoor temperatures (excluding the effect of air conditioning) and reducing solar heat gains without compromising indoor visual comfort. At the same time, they also exposed an inherent deficiency of the system's capacity to prevent air cavity overheating: air cavity temperatures were 10–30°C higher than outdoor temperatures in all facades exposed to direct solar irradiance.

Experimental and Numerical Investigation of Forced Convection in a Double Skin Façade

Flow and heat transfer of the air cavity between two glass façades designed in the box window type of double skin façade (DSF) was evaluated in a test room which was set up for measurements in the laboratory environment and analyzed under different working conditions by using a computational fluid dynamics tool. Using data from the experimental studies, the verification of the numerical studies was conducted and the air flow and heat transfer in the cavity between the two glass façades were examined numerically in detail. The depth to height of the cavity, the aspect ratio, was changed between 0.10 and 0.16, and was studied for three different flow velocities. Reynolds and average Nusselt numbers ranging from 28,000 to 56,500 and 134 to 272, respectively, were calculated and a non-dimensional correlation between Reynolds and Nusselt numbers was constructed to evaluate the heat transfer from the cavity (except inlet and outlet sections) air to the inside environment and it could be used the box window type of DSF applications having relatively short cavities.

Adaptive Box Window, developed with innovative nanomaterial, for a sustainable architecture in the Mediterranean area

A new generation of multifunctional, adaptive and dynamic facades is to be developed in the framework of the research project SELFIE to respond to the EU Directive 2002/91. The aim is to build novel adaptive envelope systems for nZEB to facilitate the exploitation of RES at building scale and simultaneously improve indoor environmental quality both in existing and new buildings. The project focuses on the design, testing and construction of innovative technological systems capable of integrating energy saving smart materials and novel technologies, for buildings located in the Mediterranean area. The Adaptive Box Window elements presented in this paper are designed to be preassembled, modular and adaptive.

THERMAL ENVIRONMENTS OF AN OFFICE BUILDING WITH DOUBLE SKIN FACADE

As a symbol of green architecture, double skin facade (DSF) represents a design which possesses many energy saving features, but due to the complexity of the system, the real performances and benefits have been difficult to predict. The objective of this study was to inform the applicability of DSFs, and contribute to the positive impacts of DSF designs. This study compared and contrasted energy savings in a temperate climate, where heating was the dominant energy strategy, and in a subtropical climate, where cooling spaces was the dominant issue. This paper focused on a university office building with a west facing shaft box window facade. The research method was a paired analysis of simulation studies which compared the energy performance of a set of buildings in two different climates. Simulation results showed a good agreement with measurements undertaken in the exiting building during a two-week period. The results specified that DSFs are capable of almost 50% energy savings in temperate and 16% in subtropical climates. Although these indicated DSFs are more suitable for temperate climates than warmer regions, the amount of energy savings in subtropical climates were also considerable. However, due to the costs of DSFs and potential loss of leasable floor area, investigations into other feasible ventilation options are necessary before final building design decisions are made.

Fast bilateral filtering using the Padé approximation

Due to the edge-preserving ability, the bilateral filter is considered as the fundamental tool in computer vision and computer graphics. However, its computational complexity has a close connection with the size of the box window. This drawback leads that the bilateral filter is inappropriate for the computational insensitive application. One way to accelerate the bilateral filter is to approximate the Gaussian range kernel by trigonometric functions and synthesise final results from a set of filtering results of fast convolutions. A novel approximation that can be applied to any range kernel is proposed. Specifically, first the Z transformation of the range kernel is obtained, then approximate the Z transformation of the range kernel using the Pade Approximation. Finally, inverse the transformation of the Pade approximation and obtain an exponential sum to approximate original range kernel, where the coefficients of the exponential basis are computed by solving a set of linear equations. Experiments show the method achieves state-of-the-art results in terms of accuracy and speed.

Thermal Models for Box Type Windows: Part 2

As the literature does not contain enough measurement data to create dedicated correlations for the Nusselt number and convective heat transfer inside box type windows, CFD simulations are performed to study the type of natural convection in such windows. Validation is attempted with the help of the turbulence benchmark of Betts and Bokhari (2000) and comparison with other simulations found in the literature. The k-ω SST model of Menter (1994) is selected to perform a wide range study of the cavity aspect ratios and Rayleigh numbers expected in box windows, enabling an analysis of the types of convections encountered. A new correlation is introduced to calculate the convective heat transfer, and finally, the study is augmented to investigate the effects the temperature stratification has on critical glazing surface temperatures.

Optimum Design Parameters of Box Window DSF Office at Different Glazing Types under Sub Interval of Intermediate Sky Conditions (20-40 klux)

Despite Double skin facade (DSF) buildings are widely deployed worldwide, daylighting strategy is not commonly incorporated in these buildings compare to other strategies. Therefore, further theoretical and experimental studies would lead to adopting daylighting strategy in DSF office buildings. The aim of this study is to investigate the daylighting performance of office building at different design parameters of box window DSF using different glazing types under sub interval of intermediate sky conditions (20-40) klux using the (IES VE) simulation tool from Integrated Environmental Solutions - Virtual Environment. The implemented design parameters are window wall ratio (WWR) of internal facade (10-100) %, cavity depth (CD) of DSF (1-2.5) m and different glazing types. The glazing types were selected from the list available in the (IES VE) simulation tool. After series of evaluations, bronze tinted coating (STOPSOL) is implemented for the exterior facade while clear float, clear reflective coating (STOPSOL), grey and brown tinted coating (Anti-sun float) and blue coating tinted (SUNCOOL float) are implemented for the interior facade. In this paper, several evaluation parameters are used to quantify the optimum design parameters that would balance the daylighting requirements of a box window DSF office versus sky conditions range (20-40) klux. The optimum design parameters of DSF office building obtained under different glazing types are highlighted as follows. When using bronze tinted coating (STOPSOL) for the exterior facade, the glazing types of interior facade that showed superior daylighting performance of DSF office at (CD of 1.0m with WWR of 70%), (CD of 1.5m with WWR of 70%), (CD of 2.0m with WWR of 70%) and (CD of 2.0m with WWR of 70%) are grey tinted coating (Anti-sun float), clear reflective coating (STOPSOL), brown tinted coating (Anti-sun float), and clear float glazing respectively. Blue Coating tinted (SUNCOOL float) of interior facade glazing failed to meet outstanding daylighting performance at any cavity depth.

Simulation aided optimization of a historic window’s refurbishment

A recurring problem in retrofitting historic windows is that most traditional means of improving their energy efficiency, e.g. the use of IG units, is often unavailable due to structural and esthetic concerns. Through a refurbishment project of traditional Central-European box windows we aim to investigate the possibility of using less intrusive methods to improve the windows’ heat balance with comparable results. Many different approaches to calculating the energy balance of windows in historic buildings are reviewed and various modelling assumptions and algorithms analyzed to highlight the depth of modelling needed for fenestration heat balance calculation in a historic context. We introduce our new research program for the task: EPICAC-BE, a MATLAB based dynamic energy simulation software. After a validation with the BESTEST suite it is used to compare different retrofit options for a prototype window with and without controlled shading devices. Results indicate the use of double glazing units is not always required or the most favorable. Utilizing the dynamic window concept by combining higher U value with higher solar transmittance with automatic interpane shading can achieve better overall results. Simulations should have a key role as they can lead to designs better satisfying both energy saving and conservational requirements.

Box window double skin façade. Steady state heat transfer model proposal for energetic audits

This study presents a simple heat transfer methodology for box double skin façade. There are a number of numerical methods described in different papers, but at local and European level it is a lack of standards or unique methodologies regarding this system. The methodology presented is an extended and corrected version of a heat transfer method through a double-glazed window described by Oosthuizen and Naylor in [1]. The box double skin façade consist of an internal double pane window and a 10mm secure glass as double skin. The methodology incorporates heat transfer by conduction and convection, considering two extreme climatic conditions for exterior temperature. The main purpose of this study is to identify the difference between single-skin façade and double skin façade from heat transfer point of view. For this purpose were taken into account and calculated face temperatures, total thermal resistances, transmittances and heat fluxes. Analyze of the heat transfer indicators were described by tabular values and by one year chart for Braşov region, in Romania. For a faster calculation some second degree polynomial equations are proposed, for finding thermal conductivity, thermal diffusivity and kinematic viscosity as a temperature function. For each property it was found one equation for air and one for argon. Argon and air are the most common gases included in window systems. Overall, the study shows an increase in envelope insulation with greatest benefits during the cold season.

The use of Dynamic Environmental Control Systems (DECS) in Cavities of Double Skin Facades for Energy Savings

Dynamic and adaptive façade components have significant potential for energy efficiency goals. However, it is not yet common to see double skin facade (DSF) buildings integrating dynamic component systems to improve their energy savings. Previous studies have repeatedly found DSF buildings to increase their energy consumption during cooling seasons. Potential exists to counteract this problem by developing a kinetic mechanism within the DSF. The Dynamic Environmental Controls System (DECS) was designed and developed to improve their performance. Its application was examined, evaluated via energy modeling simulations, and showed a decrease of the energy demand.DECS has the ability to dynamically change the cavity compartmentation between four types of DSFs: multi-storey, corridor, shaft box, and box window; and twenty-one intermediate configurations. Their performances were examined in DesignBuilder for three climate zones: Los Angeles, New York, and Houston. The focus was each case study's performance for the hottest and coldest day per climate to determine the efficiency of DSFs in extreme weather conditions. The rationale was to locate the boundaries of their performance from perspective of most improvements via DECS. The energy usage of the intermediate configurations was then examined and the dispersion of the results between all types scrutinized. The simulations were made on hourly time steps, and the most efficient configuration per hour was being selected. The aggregation of all formed the DECS pattern for each 24-hour cycle.Two major results were obtained. The application of DECS and analysis of the generated results lead to a decrease of the energy consumption of DSF buildings for the hottest day up to 3.92%, 2.52% and 1.97% per climate and for the coldest day up to 0.55%, 1.90% and 4.00% accordingly. Secondly, the methodology of the research was made less efficient by the lack of a suitable software interface. This issue is addressed.

공동주택에 적용된 Shaft Box형 발코니의 환경성능 검토

This study focus on shaft box facade, special form of box window construction. It consists of a system of box window with continuous vertical shafts that extend over a number of stories to create a stack effect. The subject building was decided by analyzing various types of exiting apartments. Shaft box type balcony was devised by setting up shaft space at a part of balcony. Air flow and indoor air temperature were simulated, performance of shaft box type balcony was compared with existing types using VE computer simulation program. Research consequence can be summarized as follow: 1) In the case of existing types, the change of window opening rate has only a little effect on the improvement of indoor temperature. But, air flow rate increased two times in the case that changed opening rate 20% to 40% 2) In the case of existing types, the growth of air flow rate has little effect on the improvement of indoor temperature. But, shaft box type represented the remarkable effect on the improvement of indoor temperature as well as the growth of air flow rate.

공동주택에 대한 Shaft Box형 이중외피의 적용에 관한 연구

The balcony of our apartment building consists of unique construction similar to double skin. It is announced broadly that double skin is very effective system in improvement of natural ventilation and indoor thermal environment, and outdoor sound protection. So, for the improvement of indoor climate and energy saving, many peoples studied about environmental performance of our balcony construction. This study focus on shaft box facade, special form of box window construction. It consists of a system of box window with continuous vertical shafts that extend over a number of stories to create a stack effect. Proto-type was decided by analyzing various types of exiting apartments. Shaft box type balcony was created by setting up shaft space at a part of balcony. Air flow and contribution of air temperature were simulated, performance of shaft box type balcony was compared with existing balcony. Finally, we confirmed that shaft box type balcony has many possibility for improvement of indoor environment.

Condensation risk assessment on box windows: the effect of the window–wall interface

Windows generally have the lowest temperature index in current building types, and will consequently be the primary location for interior surface condensation. Surface temperatures can easily be calculated using thermal finite-element models, but these generally omit the effect of convection in the windows and the window–wall interface. Hence, there is a need to determine if specific interface details provide potential for condensation on the window components in which air leakage paths may be prominent. The article reports on a laboratory evaluation of condensation risk assessment in a hotbox with varying pressure differences and the introduction of deficiencies. It was concluded that the effect of the type of insulation in the window–wall interface was very low for isobaric boundary conditions, whereas it has a significant effect when pressure differences are applied.

Validity of Uniform Flow Hypothesis in One-Dimensional Morphodynamic Models

Local-uniform-flow (LUF) hypothesis is a simplification of the governing equations describing river morphodynamics, which is needed to determine the evolution of the bed profile and bed-material composition in the case of large time and space scales. This paper presents a rigorous analysis of the full one-dimensional river hydrodynamic and morphodynamic mathematical model compared to its LUF approximation. The analysis establishes two criteria to assess the validity of the LUF hypothesis: (1) a criterion for rivers in equilibrium and (2) a criterion for evolving rivers (i.e., in nonequilibrium). The first criterion is based on the concept of the morphological box. Variations of the river bed longer than the box length are adequately reproduced by the LUF hypothesis, whereas only spatially averaged values are resolved within the box. The second criterion is based on the concept of an evolution window. Temporal variations represented by wave periods larger than the evolution window can be adequately reproduced by the LUF hypothesis, whereas variations with shorter periods are averaged within this window. The minimum size of morphological box and evolution window that limit the error introduced by the LUF hypothesis increases when the Froude number decreases. Further, the minimum size of the evolution window increases for decreasing sediment concentration and increasing mixing layer thickness (i.e., for larger bed forms). The LUF hypothesis is therefore best applied to small mountain rivers for which both the minimum size of the morphological box and the evolution window is relatively small, so that spatial and temporal variations can be resolved in more detail. Applications using the LUF hypothesis for large watersheds (including the lowland portion of the fluvial network) are possible, but are limited to simulations over larger spatial and temporal intervals.