Solar Radiation Control Using Electrochromic Smart Windows, an Approach toward Building Energy Optimization

This study comprehensively evaluates the energy-saving potential and visual comfort aspects of electrochromic (EC) smart windows in a hot-humid climate office building. Using an advanced building simulation tool, EC windows are compared to conventional low-E glazed windows, considering two control triggers: daylighting level and glare control. The primary objective is to determine energy savings achievable with EC windows while addressing visual comfort. Detailed analysis of the building’s energy performance and indoor environment is conducted. Results show significant energy savings of 23% with EC windows using daylighting control but limited visual comfort in some zones. Conversely, EC windows with glare control achieve 17% energy savings while maintaining visual comfort throughout the building. These findings highlight the potential of EC windows with glare control in saving energy and maintaining visual comfort in hot-humid office buildings. Further research is needed to optimize performance for different building types and climates. In conclusion, this study provides insights into energy-saving capabilities and visual comfort considerations with EC smart windows, emphasizing the importance of appropriate control triggers for maximizing energy savings and occupant comfort. Future investigations should explore EC window performance across diverse building typologies and climates to enhance the benefits of this innovative technology.

In recent years, with the increasing demand for building energy efficiency and comfort in daily life, electrochromic smart windows have attracted widespread attention. Electrochromic smart windows utilize electrochromic material (ECM) technology to change the color or transparency of the window under the action of an electric field, thereby regulating the light and heat entering the room and achieving energy-saving effects. A bistable electrochromic material is a material that can switch between two color states and maintain one of these states without an external electric field. Although ECMs with bistable properties can significantly reduce energy consumption, current research on their application in smart windows is limited. Therefore, three conjugated extended viologen polymers with thiophene derivative bridges, PDV-MMA, PBV-MMA, and PTV-MMA, were designed and synthesized, and electrochromic devices (ECDs) were prepared. The introduction of thiophene derivatives not only prolongs the effective conjugated chain length of viologen, but also extends the electrochromic (EC) response to the near-infrared (NIR) region. In addition, by inserting different thiophene derivatives to separate the two pyridinium moieties, viologen polymers emit strong fluorescence that can be quenched by applying a negative voltage. The electrochromic device based on PDV-MMA material has fast response time (1.8 s), low turn-on voltage (-0.9 V), high color contrast (73.7%), high coloring efficiency (550 cm2/C), and cycling stability (3300 cycles). In addition, ECD based on PDV-MMA exhibits bistable characteristics, with only a 10% transmittance decay within 221 min, displaying clear patterns even after 20 h of power outage, and significantly reducing indoor temperature (7.0 °C) in simulated indoor environments. These characteristics make the application of electrochromic smart windows highly attractive in energy-efficient buildings. The study also demonstrated an intelligent window system driven by a solar cell (SC), further validating its feasibility in practical applications.

مطالعه مخاطرات طبیعی یکی از مهم‌ترین اصول اولیه برای توسعه شهرهای درحال‌توسعه و گسترش تأسیسات زیربنایی است. ارزیابی فعالیت‏های ژئودینامیکی با استفاده از داده‏های ریخت‏شناسی یکی از روش‏های مهم و کاربردی در این راستا تلقی می‏شوند. در این مقاله سعی شده با استفاده از داده‏های سنجش‌ازدور، مطالعات صحرایی نسبت به شناسایی چین‏های فعال در شهرستان یزد اقدام و برای اولین‏ بار چین‏های فعال منطقه شناسایی شوند. بررسی‏ها نشان می‏دهد در محدوده شرق تا شمال‏شرق این شهر باستانی تعداد حداقل 5 چین فعال وجود دارد که به‌عنوان مخاطرات جدی برای منطقه محسوب می‏شوند. مقایسه موقعیت این چین‏ها با فعالیت‏های لرزه، حاکی از انطباق برخی کانون‏های زمین‏لرزه‏ای در این منطقه است. بدیهی است عبور هرگونه تأسیسات و شریان‏های حیاتی ازجمله راه‏های مواصلاتی، خطوط گاز، آب و یا سایر زیرساخت‏های شهری در این منطقه نیازمند تمهیدات ویژه می‏باشد.

Electrochromic (EC) smart windows are one of the main applications of EC materials for green buildings. By using EC smart windows in buildings, desirable energy savings in air conditioning and artificial lighting systems, as well as occupant comfort, are achieved simultaneously if the colouration of EC smart window is regulated by a suitable operation and control algorithm. In this chapter, the characteristics of EC smart windows are evaluated from the perspective of green building applications. Energy savings, as the top merit of EC smart windows, are mainly derived from reductions in energy use for air conditioning and cooling/heating peak load demand, and the reduction of artificial lighting energy consumption, while occupant comfort, especially visual comfort, can be improved by adjusting the colouration of EC smart windows to reduce the risk of glare. Although some challenges such as scalability and price act as obstacles to the widespread use of EC smart windows, many opportunities are emerging for future development. The improvement of EC materials, connection with the Internet of Things (IoT), and integration with passive building technologies are also discussed in this chapter. Because of these potentials to meet the huge demand of energy savings and occupant well-being in buildings, the market for EC smart windows is expected to increase dramatically in the near future.

Windows through heat exchange play a vital role in energy saving for realizing a net‐zero carbon emission society. Dual‐band electrochromic (EC) smart windows by dynamically regulate visible (VIS) and near‐infrared (NIR) light are necessary for improving both building energy efficiency and habitant comfort. However, the rational design of high‐performance electrochromic devices (ECDs) suffers sluggish EC response due to the slow ion transport. In this work, a locally dissociated Li+ concept is proposed to construct a solid‐state polymer electrolyte (SPE) with ultrafast Li+ transport. The succinonitrile (SN) is employed to loosen the Li+‐anion pair and the crystallographic C─O chain in the poly(ethylene glycol) methyl ether methacrylate (PEGMA) electrolyte by its strong solvation capability. The as‐prepared SPE shows a high ionic conductivity of 6.48 mS cm−1 at 30 °C and a high transmittance of >90%. The SPE‐based EC smart windows exhibited a fast switching speed (3.0/3.2 s for coloration/bleaching), a high coloration efficiency (CE) of 373.8 cm2 C−1, and a high optical modulation in the full solar spectrum (85%, 70%, 43% at 673, 1200, and 1600 nm, respectively). Finally, the SPE‐based EC smart windows shows three working modes with a temperature regulation range of 19.1 °C, exhibiting great potential in practical application.

Study on the impact of photovoltaic electrochromic modular smart window on indoor environment

Electrochromic (EC) technology can modulate visible-infrared (VIS-IR) optical properties under electrical stimulation, showing broad application prospects in smart windows and so on. This work demonstrates a colorful electrochromic smart window by employing vanadium oxide V2O5 with polaronic effects and ITO films with localized surface plasmon resonance (LSPR) to realize outstanding VIS-IR dual-band optical modulation and EC performance. It shows yellow and green reversible color switching, fast response (3.0 s for VIS bleaching and 0.32 s for IR emissivity rising), high optical modulation amplitude with ΔTmax = 53.2% at 850 nm and Δεmax = 0.57 at 4.8 μm, and a long lifetime of 104 reversible cycles. The new design methods of the excellent stability VIS-IR modulation in this smart window emphasizes the role of multiband modulation for the diversification of all the EC applications.

A TOC- and deposition-free electrochromic window driven by redox flow battery

Multi-band electrochromic (MBEC) smart windows, capable of decoupled management of solar radiation (visible and near-infrared transmittance) and thermal radiation (mid- and long-wave infrared emissivity), are crucial for zero-energy buildings and adaptive optical systems. However, they have not yet been developed due to the inherent material design challenges and kinetics-stability trade-offs. Inspired by lotus root vessels, we develop vertically aligned nano-helix tungsten oxide (NH-WO3) films with amorphous-crystalline heterophase. The multiscale microstructure provides numerous active sites, enhances local electric fields, and alleviates stress during repeated cycling. Consequently, NH-WO3 achieves unprecedented quad-band electrochromic performances with decoupled photothermal modulation across the visible to long-wave infrared spectra, featuring large optical contrast (ΔTVIS-NIR ~ 79%), significant temperature and emissivity variation (ΔT = 9.3 ℃, Δε = 0.47@5 μm), ultrafast switching (3.9/1.9 s@780 nm, 2.8/2.5 s@990 nm), and robust cyclability (10,000 cycles with only 9.1% optical-contrast loss). Furthermore, a prototype smart window based on the NH-WO3 film maintains a comfortable indoor temperature of 26 ℃ even under continuous AM 1.5G solar irradiation for 1 hour. This bio-inspired nano-helix design provides an efficient strategy for the development of advanced next-generation photothermal management smart windows towards practical energy-efficient architectures and adaptive optics.

Effect of electrochromic windows on energy consumption of high-rise office buildings in different climate regions of Iran

Integrative economic framework incorporating the Emission Trading Scheme (ETS) for U.S. Residential energy systems

Numerical and experimental study on the thermal performance improvement of a triple glazed window by utilizing low-grade exhaust air

Radiative thermal management (RTM) smart windows represent an emerging class of adaptive building-envelope technologies that combine dynamic spectral regulation with passive heat dissipation through the atmospheric window. By simultaneously modulating visible light (VIS), near-infrared solar radiation (NIR), and mid-infrared thermal emission (MIR), these systems enable year-round thermal regulation with reduced building energy consumption. This review systematically summarizes recent progress and mechanisms of RTM smart windows. Compared with existing reviews that mainly focus on static radiative cooling materials or single-mode smart windows, this review emphasizes integrated RTM smart windows featuring tri-band (VIS/NIR/MIR) spectral regulation and dual-responsive mechanisms. Firstly, the fundamental principles of radiative thermal management and intelligent response mechanisms are introduced, followed by an overview of key performance. Secondly, the latest progress in electrochromic, thermochromic, and photochromic RTM smart windows is comprehensively reviewed. Particular attention is devoted to dual-responsive mechanism RTM smart windows, which integrate passive and active control to achieve synergistic performance. In summary, this review presents an overview of recent advances and underlying mechanisms in intelligent windows for radiative heat management.

Electrochromic Smart Windows Ultra-large-scale, high-performance electrochromic smart windows are prepared using TAIG method, which exploits the instability of black phosphorus to achieve the control of the structural water and oxygen vacancy content in WO3 films. The simplicity of TAIG makes the commercialization of smart windows to be highly accessible. More details can be found in article number 2409790 by Maofei Tian, Rongzong Zheng and Chunyang Jia.

Phase Change Materials (PCM) may be excellent thermal insulation due to their poor conductivity and high heat capacity. Researchers are adding PCM to windows. This integration modifies internal surface temperatures and delays peak temperatures to improve indoor thermal comfort. This work investigates experimentally and numerically the impact of the different filling materials in four Triple Glazed Windows (TGW) configurations in an Iraqi environment: the first window filled two cavities with air (standard); the second window has one cavity filled with a PCM and the other with air; the third window has blinders with various tilt angles in one cavity and PCM in the other cavity; and in the fourth window, both cavities are filled with PCM. Numerically utilizing Computational Fluid Dynamics to evaluate the thermal performance of TGW. In August, when the solar radiation was at its maximum (623 W/m2), the results showed that the peak interior surface temperature dropped by 4.51, 13.28 and 11.53 % in the TGW configurations (PCM-air), (blinder-PCM), and (PCM-PCM), compared to the standard TGW. The fourth window increased the time lag by 2 h, effectively shifting the load and in the third window, the best tilt angle blinder is 45°