Electrochromic Glass Research Articles

Double-Shell Encapsulation of Lead-Free Tin Halide Perovskite for Self-Powered Smart Windows.

Luminescent solar concentrators (LSC) have the potential application in building integrated photovoltaic (BIPV). 0D tin-based perovskites are a promising embedding phosphor in LSC due to the large Stokes shift and high photoluminescence quantum yield. But the instability and uncontrollable crystal growth are severe limiting their successful utilization in device fabrication. To tackle these issues, double-shell encapsulated configurations are presented, soft ligands of hypophosphorous acid and hard-shell of hollow mesoporous silica are simultaneously suppressing the oxidation of Sn2+ and restricting crystal growth within nano-matrix. The stable phosphor is subsequently embedded into LSC for harvesting solar energy and the resulting output power efficiently drives the combined electrochromic glass under natural light. These fabricated devices also offer the self-adaptable switch on/off functionality to regulate light absorption with variable solar irradiation intensity in real time. This approach is anticipated to open new avenues for utilizing lead-free perovskite nanomaterials in self-powered smart windows for BIPV.

Assessing the impact of glazing and window shade systems on view clarity

Windows provide access to daylight and outdoor views, influencing building design. Various glazing and window shade materials are used to mitigate glare, overheating and privacy issues, and they affect view clarity. Among them, we evaluated the effect of window films, electrochromic (EC) glass, and fabric shades on view clarity. We conducted an experiment with 50 participants using visual tests adapted from clinical vision tests (visual acuity, contrast sensitivity, color sensitivity) and images displayed on a computer monitor in a controlled laboratory. Window films and EC glass tints outperformed fabric shades in visual acuity, contrast sensitivity and view satisfaction with the exception of the darkest EC tint state and dark grey VLT 3% shade for color sensitivity and view satisfaction. The EC tints pose internal reflection issues and fabric shades are preferred for visual privacy. Window films and EC glass hinder participants’ blue–green color discrimination while fabric shades also decrease red–yellow color discrimination. Visual acuity predicts view satisfaction and contrast sensitivity is the strongest predictor for visual privacy. Generally, higher visible light transmittance and lower solar reflectance (darker color) enhance human visual performance. The proposed workflow provides an experimental procedure, identifies the primary variables and establishes a predictive framework for assessing view clarity of fenestration.

Effects of Lithium bis(trifluoromethanesulfonyl)imide loading on thermal, mechanical and ion conducting properties of specialty interlayer films derived from scrap Polyvinyl butyral

This work investigates the feasibility of using scrap poly(vinyl butyral) (PVB) film derived from laminated glass factories as an ion-conductive interlayer film for producing electrochromic glass. The process uses PVB films made from masterbatches containing 10 to 60 wt% lithium bis(trifluoromethane sulfonyl)imide (LiTFSI). The investigation focused on how LiTFSI loading affected both the PVB masterbatches and the final PVB films. Higher LiTFSI loading correlated with increased ionic conductivity. The best electrochromic devices are obtained when the PVB films are directly prepared from the masterbatch without additional PVB flakes dilution during extrusion. The highest ionic conductivity 2.72 × 10−4 S/cm, is achieved from a masterbatch containing neat PVB and scrap PVB flakes with 60 wt% LiTFSI. Additionally, LiTFSI acted as a plasticizer for PVB, lowering the glass transition temperature and increasing the PVB film percent elongation.

Design and Implementation of Electrochromic Smart Windows with Self-Driven Thermoelectric Power Generation.

Electrochromic smart windows can achieve controllable modulation of color and transmittance under an external electric field with active light and thermal control capabilities, which helps reduce energy consumption caused by building cooling and heating. However, electrochromic smart windows often rely on external power circuits, which greatly affects the independence and portability of smart windows. Based on this, an electrochromic smart window driven by temperature-difference power generation was designed and implemented. This smart window provides automatic and manual control of the reversible cycle of electrochromic glass from light blue to dark blue according to user requirements and changes in the surrounding environment, achieving adaptive adjustment of visual comfort and reducing energy consumption. The infrared radiation rejection (from 780 to 2500 nm) of the electrochromic smart window is as high as 77.3%, and its transmittance (from 380 to 780 nm) fluctuates between 39.2% and 56.4% with changes in working state. Furthermore, the temperature in the indoor simulation device with electrochromic glass as the window was 15 °C lower than that with ordinary glass as the window after heating with a 250 W Philips infrared lamp for ten minutes. After 2000 cycles of testing, the performance of the smart window was basically maintained at its initial values, and it has broad application prospects in buildings, vehicles, and high-speed rail systems.

OPTIMIZING ELECTROCHROMIC SMART GLASS WINDOWS PERFORMANCE WITH SOLAR CONTROL FOR SUSTAINABLE OFFICE ENVIRONMENTS IN THE HOT AND HUMID CLIMATE OF SAUDI ARABIA

ABSTRACT Energy-saving strategies are of paramount importance, especially in office buildings located in hot-humid climates. This study explores the potential for energy savings and assesses visual comfort in such environments by introducing Electrochromic (EC) smart glass in the window glazing. To bolster credibility and provide essential information, we employ a state-of-the-art building simulation tool. The research focuses on evaluating the energy performance and visual comfort of EC glass windows when controlled by solar controllers. Through meticulous simulations, we pinpoint the optimal setpoint radiation levels for EC glass windows across all building orientations. The results conclusively indicate that deploying EC glass windows with solar controllers, each set to the recommended radiation levels, leads to remarkable energy savings, up to 20%. Importantly, these savings are achieved without compromising visual comfort in any of the building's zones, regardless of orientation. This research underscores the potential for EC glass windows to significantly improve energy efficiency in office buildings, emphasizing their applicability in hot-humid climates. The findings call for further exploration in different building types and climate zones, as the practical implications of these results could revolutionize energy-efficient building design and retrofits.

Joint control strategy for daylighting and artificial lighting based on mathematical modeling and differential evolution

ABSTRACT Creating a healthy and comfortable light environment in buildings is crucial for enhancing individuals’ well-being and work efficiency. The joint control of daylighting and artificial lighting has become a research hotspot in the field. The application of emerging electrochromic glass and dimmable luminaires addresses the challenge of managing illuminance levels through a combination of daylight and artificial lighting control. The glass control strategy is determined under specific conditions, and the differential evolution (DE) is employed to optimize the dual-channel output percentages of light-emitting diode (LED) luminaires for designated combinations. The results show that the modeled and algorithmically solved average illuminance exhibits an error rate of less than 1% from the target values. The joint control strategy takes into account visual effects of the light environment, with potential benefits for energy efficiency, occupant comfort, and cognitive performance. It contributes to a holistic understanding of lighting control strategies that optimize illuminance in indoor spaces, ultimately fostering a healthier and more productive environment for occupants.

A study on the impact of electrochromic glazing on indoor environment

The study investigates the impact of electrochromic glazing on indoor environments, providing valuable insights for the practical application of electrochromic glazing. Three rooms were constructed in Zhangjiakou City, China, equipped with different shading devices (electrochromic glazing, venetian blind, and base case of the glazing with no shading). Through experiments and simulations, the analysis of the overall indoor illuminance revealed that electrochromic glass, in its dark state, effectively reduces the average indoor illuminance while ensuring a uniform distribution of illuminance throughout the space, meeting the specified values for the discomfort glare index most of the time. During nighttime lighting, the average illuminance in room with electrochromic glazing was 42% higher than in the control rooms. In winter, the daily heat supply quantity in room with electrochromic glazing was 4.4%–21.9% higher than in the control rooms. In summer, the heat gain in room with electrochromic glazing was 19.1%–41.8% lower than in room with base case of the glazing. On a sunny day in winter, the room with electrochromic glazing exhibited more stable PMV values compared to the room with base case of the glazing, with a 20% increase in the duration of PMV thermal comfort compliance, but its Percentage of PPD values were inferior to the room with base case of the glazing. In summer, the room with electrochromic glazing outperformed both the room with venetian blind and the room wtih base case of the glazing in terms of PMV and PPD values.

Transparent succinonitrile-modified polyacrylate gel polymer electrolyte for solid electrochromic devices

Transparent gel electrolytes have the advantage of optical transparency, higher ionic conductivity, and better electrode adhesion compared with solid inorganic electrolytes, which is of great significance in solid-state electrochromic glass and other electrochemical applications. Here, succinonitrile-modified polyacrylate gel polymer electrolyte (SN-GPE) has been successfully synthesized via an in-situ thermal polymerization under mild conditions. Adopted succinonitrile significantly improves ionic conductivity from 0.02 mS·cm−1 to 4.02 mS·cm−1, maintaining advantageous features such as high transparency and excellent electrochemical performance. The optimized SN-GPEs with good adhesion to both counter and working electrodes were assembled in semi-devices with a configuration of glass/FTO/WO3/SN-GPE/FTO/glass, which showed an excellent optical modulation (ΔT) of 34.5 % at λ = 633 nm and fast response time 4 s/20 s for bleaching/coloration by applying a bias voltage ± 2.8 V, and promising cycling stability with ΔT maintaining 90 % of the original after 2840 cycles, indicative of an extensive potential in the applications of the solid or flexible electrochromic devices. This work significantly broadens the transparent electrolyte family for advanced large-scale electrochromic devices.

Transfer learning for forecasting hourly indoor air temperatures of buildings with electrochromic glass

AbstractThis study aimed to employ transfer learning with a fully connected feed‐forward neural network for forecasting the indoor air temperatures of adaptive buildings with electrochromic (EC) glass. This study predicted indoor air temperatures for an intermediate season requiring heating and cooling. Forecasting indoor air temperature can help control the EC glass to avoid overheating the interiors. The forecasting times for the predictions varied from 1 to 5 h between early morning and noon, which is when the interior is often overheated. The pretrained model was created using multilayer perceptron learning with the simulation data of a source building in Tokyo and transfer learning with feature‐based extraction models that used datasets from the simulation of target buildings in Tokyo and Fukuoka. Further, the effects of facade orientation were investigated. The root mean squared error (RMSE) of the pretrained model varied from 0.027 to 0.935 when predicting the indoor air temperatures from 1 to 5 h. The RMSE of the transfer learning models using the pretrained model with the same and different orientations varied from 0.022 to 1.205 and from 0.9301 to 2.566. This study demonstrated that utilizing predicted indoor air temperatures to control EC glass can help protect against overheating.

Comparison of fast daylighting climate-based simulation methods for parametric design: two-phase, three-phase method and path tracing

ABSTRACT Computer modeling and simulation are essential for predicting architectural solutions performance. When integrated into the design process; they are known as performance-based design. During the design process, fast analytical cycles are required. However, daylighting simulations are challenging due to computational processing and time requirements. This paper presents a comparative study of fast daylight simulation methods, two-phase, three-phase and path tracing, in a hypothetical commercial building located in Miami, Florida. Five types of static glass and one electrochromic glass were tested with six parametric models of a translucent horizontal shading device. Daysim was used as reference. The two-phase method produced results similar to the reference results with faster processing times for static facades. For dynamic facades, the path tracing method with the tested interface enabled faster simulations and parametric variations. However, the three-phase method yielded a lower average error.

The Potential of Switchable Glazing in Cooling Dominated Climates

The design trend of most commercial and office buildings over the past three decades focused on attaining a façade design with the highest possible window to wall ratio. Whereas this approach appears to satisfy the aesthetic scope of developing buildings that look ‘modern and transparent’ to maximise on real estate value, the demand for heating and cooling of these buildings tends to fall short of what one should expect. Literature review shows the possible benefits of switchable glass. This paper proposes a methodology for a novel switchable glazing assembly identified as having the potential of offering increased occupant comfort, particularly in providing sufficient daylight and glare control without diminishing the view quality. The hypothesis is that switchable glazing may have a substantial potential to achieve lower cooling loads and improved indoor visual comfort without compromising views and a positive outlook.

Optimal design method for electrochromic window split-pane configuration to enhance building energy efficiency

Electrochromic (EC) windows can prevent glare by adjusting their tinting state, but the tinted EC glass will affect the use of daylight in the room, resulting in the increase of lighting energy consumption. Splitting the EC window into several panes and tinting only a portion of them can effectively mitigate the conflict between glare prevention and the usage of daylight. However, there is a lack of design methods for EC window split pane configurations to realize further lighting energy-saving potential. To address this problem, this study proposed an optimal design method for EC window split pane configuration. This method is based on the glare calculation model and aims to obtain the minimum tinted area hours (TAH) of the EC window. Taking a south-facing EC window office building in Beijing as a case study, the effectiveness of the proposed design method was investigated by simulation. Results show the proposed design method identified the most energy-efficient and comfortable split panes scheme. By combining with the split-pane glare control method, 95.3% of intolerable glare was prevented, and a useful daylight illumination index of 73.3% was achieved. It also significantly improved building energy efficiency, saving 29.8% of lighting energy consumption compared to whole window design scheme. This study provides a promising design methodology for the high-performance application of EC windows in buildings.

Effects of electrochromic glass window on energy efficiency, thermal and visual performances under tropical climate

This study investigated the thermal, visual environments of real-life climate chambers installed with a full-scale dark gray electrochromic glass window (ECW) under tropical climate in Singapore. Two large-scale climate chambers were built and installed with electrochromic windows or 6 mm single clear glass for comparison, and their thermal and visual performances and effects on the efficiency of air-conditioning were real-time measured and analyzed in detail. Compared to the chamber installed with 6 mm glass, the coefficient of performance (COP) of the air conditioner can be enhanced by 29.64 % and 45.40 % if replaced by bleached and tinted ECWs, respectively. Our study shows that ECW can efficiently reduce around 80 % of the heat flux passing through the indoor under both states, and provide a cooler and more comfortable thermal environment. In contrast, the bleached ECW showed the best performance with 39 % of the daytime spent with a comfortable visual environment without glare. With a 4 % solar heat gain coefficient and a 0.1 % visible light transmission, the fully tinted ECW could reduce the mean radiant temperature and operative temperature by up to 4.7 °C and 11.6 °C, respectively, when compared to the 6 mm glass. The operative temperature of the chamber with fully tinted ECW was even 0.6 °C lower than that of the bleached state. In conclusion, the fully gray tinted ECW showed superior thermal performance with high energy efficiency, and the bleached state gave better visual environment comfortably and economically.

Sun-Fi: Architecting Glass for Sunlight Data Transmission

Solar energy, as a sustainable power resource, has mainly been used for electricity generation and heating purposes. Nevertheless, large amounts of daylight are underutilized and primarily used for indoor lighting. In this article, we investigate exploiting sunlight as a green information carrier by passively modulating its power to stream data. Switchable glass technologies can be employed to manipulate the ambient light allowing optical wireless communications. In this context, we explore candidate smart-glass technologies and give an overview of the sunlight modulation communication system, called Sun-Fi. Then, based on the liquid crystal devices technology, we discuss the newly proposed architecture known as dual-cell liquid crystal shutters (DLS), which can establish a flicker-free communication link. Afterward, we stack the DLS elements in an array form while adopting polarization-based modulation and time division multiplexing to modulate the sunlight and transmit the required data. Finally, we define several open issues of the sunlight communication system and provide potential solutions.

Electrochromic Glass Design with Solar Energy

With the effect of the use of non-renewable energy sources, our world is facing the danger ofglobal warming. The use of fossil fuels increases the rate of carbon dioxide emitted into the atmosphere,and thus, global warming, unfortunately, brings climate changes with it. Minimizing this danger can onlybe achieved by turning humanity towards renewable energy sources. Solar energy is a reliable,environmentally friendly and inexpensive source. The aim of this study is to perform the electrochromicglass by using solar energy without any electricity costs and thus to encourage people to more renewableenergy technologies. In this study, it is desired to present a new technology design that is an alternative tothe classical window glasses used in our country by using solar energy. The solar panel converts the sun'senergy into electrical energy by using solar energy, and with this electrical energy, the opaqueelectrochromic glass changes color and becomes transparent. Thus, the glass makes the interior of the roomshow with this color change. This system, which works with a photovoltaic panel, operates theelectrochromic glass with solar energy without the need for extra energy. For example, with this system, italso eliminates the need for curtains or roller blinds used in working and living areas and provide ease ofuse according to the desired conditions. This system can be used not only for this purpose, but alsoanywhere that is required for smart glass design and has solar energy potential. For this study,electrochromic smart glass obtained by placing polymer dispersed liquid crystal (PDLC) smart materialand this material was sandwiched between indium tin oxide window films with the help of Polyvinyl butyral(PVB) layer. This electrochromic glass system is designed by connecting the connection cable and the onoff switch cable to the photovoltaic panel. In this study, electrochromic glass performance was tried to beanalyzed depending on the exposure time of the photovoltaic panel in the sun.

The Effects of Luminaire Glass Type on Road Parameters in Road Lighting

The aim of this study is to draw attention to the light transmittance level of special glasses with low light transmission. Although it is known that the light transmittance of these special glasses is low, this study is important in terms of knowing the light transmission rate in question and what kind of light problems it causes in practice, because these special glasses can be used for road lighting in some special climatic conditions, for some experiments, or for the use of light in architectural designs. For this reason, it is important to know these special glasses light transmittance properties. As the light transmittance of the luminaire glasses increases, the amount of light on the road also increases. In other words, the light source or glass type affects the lighting performance of the road. The luminaire affects the light emitted from glass-type luminaires and reduces the luminous flux falling from the lamp to the road surface. For this reason, the lamp’s luminous flux with the appropriate power should be increased according to the light transmittance factor of the glasses. Otherwise, the conditions, specified in the CIE road lighting standards, cannot be met. For this purpose, luminaire glasses with different properties that can be used in road lighting were analysed according to their light transmittance of single glass (4 mm), double glass (4 mm), electrochromic glass (reflective), electrochromic glass (absorbent), and thermochromics glass. As a result, it has been determined that when the luminaires used in road lighting are without glass or the luminaire glasses are made of different materials, the lamps luminous fluxes should be increased according to the transmittance coefficient of the glasses.

Effect of metal dopants on the electrochromic performance of hydrothermally-prepared tungsten oxide materials.

Electrochromic (EC) glass has the potential to significantly improve energy efficiency in buildings by controlling the amount of light and heat that the building exchanges with its exterior. However, the development of EC materials is still hindered by key challenges such as slow switching time, low coloration efficiency, short cycling lifetime, and material degradation. Metal doping is a promising technique to enhance the performance of metal oxide-based EC materials, where adding a small amount of metal into the host material can lead to lattice distortion, a variation of oxygen vacancies, and a shorter ion transfer path during the insertion and de-insertion process. In this study, we investigated the effects of niobium, gadolinium, and erbium doping on tungsten oxide using a single-step solvothermal technique. Our results demonstrate that both insertion and de-insertion current density of a doped sample can be significantly enhanced by metal elements, with an improvement of about 5, 4 and 3.5 times for niobium, gadolinium and erbium doped tungsten oxide, respectively compared to a pure tungsten oxide sample. Moreover, the colouration efficiency increased by 16, 9 and 24% when doping with niobium, gadolinium and erbium, respectively. These findings suggest that metal doping is a promising technique for improving the performance of EC materials and can pave the way for the development of more efficient EC glass for building applications.

Effects of Electrochromic Glass Window on Energy Efficiency, Thermal and Visual Performances Under Tropical Climate

Effects of Electrochromic Glass Window on Energy Efficiency, Thermal and Visual Performances Under Tropical Climate

Effects of voltage variation on heat and stress distributions in the electrochromic glass

Electrochromic glass has been used in many applications, such as the building envelope, because its light filtration can be adjusted in a controllable manner using low input energy. Electrochromic glass is a composite glass that consists of five layers. These five layers have two layers of glass, two layers of Indium Tin Oxide (ITO) and a layer of Poly (3-hexylthiophene), which is an electrochromic film. When a current passes through the glass, a voltage difference occurs, resulting in a redox reaction at an electrode layer. This causes the glass to change colour from transparent to opaque, resulting in a change in radiation absorption, which affects the heat transfer process. The study investigates temperature and thermal stress distributions in electrochromic glass by adjusting an input voltage in a range of 0–2.6 V. The spectral absorbance data at all light spectrum ranges were experimentally obtained. The averaged absorbance data were used for calculating the heat generation rate, and used as the input parameter for three-dimensional (3D) multiphysics simulations. The maximum temperature and thermal stress of the electrochromic glass are reached at 1.8 V according to the high rate of heat generation. The peak value of stress occurs at the interface between ITO and electrochromic layers. This study provides information regarding the heat transfer process and the stress induced in the electrochromic glass which varies with the applied voltages and can be applied to glass industries and many other related fields.

Study on the impact of partition photovoltaic electrochromic windows on building lighting environment and energy saving

Electrochromic (EC) window can adjust the indoor lighting environment, but its control strategy will greatly affect its performance and bring additional energy consumption. Therefore, this research integrates photovoltaic (PV) shading technology and designs an optimized partition photovoltaic electrochromic (PV-EC) window, which mainly includes the PV area covered with crystalline silicon cells, the EC area with electrochromic glass and the transparent area used to ensure lighting environment in cloudy days. Because each area can be controlled independently, under different control strategies, the system can realize the accurate regulation of lighting environment. Moreover, the system can use the energy generated by PV modules to be self-sufficient on energy and can also use PV modules as sunshade device. A partition PV-EC window building internal lighting environment test rig was built to explore the impact of partition PV-EC window on lighting environment under different control strategies. Among four strategies, the useful daylighting illuminance of illuminance strategy is the largest and reaches 79.88 %. Therefore, from the perspective of lighting environment, illuminance strategy should be chosen for partition PV-EC windows. On the grounds of the building energy simulation results, radiation strategy can save energy by 13.71 % compared with that of ordinary Low-E windows in high radiation areas. Therefore, from the perspective of building energy consumption, radiation strategy should be chosen for partition PV-EC windows. The above results show that partition PV-EC windows can be beneficial to create a better lighting environment without bringing additional energy burden and has a certain promotion value.