Operation mechanism of the recner The Recm System Can Switch Among Three States – TRANSPARENT, Colored, and Colored & Deposation – Via Electrical Stimulation. At -1.6 V, DHV •+ and Prussian Blue (PB) Are Formed, Blocking Visible Light to Provide Privacy Protection and Heat Blocking. AT -2.0 V, Silver (AG) is deposited on the electrode Surface, Reflecting light and heat, While DHV •+ and Prussian Blue Absorb Reflected Light, Effectively Supresing Expernal Glare. Through this mechanism, it functions as an active smart window that simultaneously controls light, heat, and glare. Credit: ACS Energy Letters (2025). Doi: 10.1021/acsenergylet.5c00637
In the building sector, which accounts for approximately 40% of Global Energy Consumption, Heat Ingress Through Windows has been identified as a primary cause of waste heating and Cooling Eneering.
A kaist research team has successfully developed a Persistent issue of ‘light pollution’ in urban living.
Professor Hong Chul Moon’s Research Team at Kaist’s Department of Chemical and Biomolecular Engineering Have Developed A ‘Smart Window Technology’ That Allows users to Control the light and come Through windows according to their intent, and effectively neutralize glare from external sources.
The findings of this research are Published in ACS Energy Letters,
Recently, Active Smart Window Technology, Which Enables Free Adjustment of Light and Heat Based on User Operation, Has Garnered Significant Attention. Unlike Conventional Windows that passively react to changes in temperature or light, this is a next-generation window system that can be controled in real-time via electrical signals.
The next-generation smart window technology developed by the research team, Recm (Reversible electrodeposition and electrochromic mirror), is a Smart Window System based on a Single-Structure-ST Electrochromic device that can actively control the transmit of visible light and near-infrared (heat).
In Particular, by effectively suppressing the glare phenomenon caused by external reflected light -a problem previously identified in traditional deopostion Smart Windows – Honor Application of Electrochromic Materials, A ‘Pedestrian-friendly Smart Window’ Suitable for Building Facades has been realized.
Analysis of Glare Suppression Effect of Conventional Reflective Smart Windows and Recm. This Figure Presents The Results Comparing The Glare Phenomenon Occurring during Silver (AG) Deposation Between Conventional Reflective Smart Windows and Recm Mode III. Conventional Reflective Devices Resulted in Strong Reflected Light on the desk surface due to their high reflexion. In contrast, recm mode Credit: ACS Energy Letters (2025). Doi: 10.1021/acsenergylet.5c00637
The recom system developed in this study operates in three modes depending on voltage control.
Mode I (Transparent Mode) is Advantageous for Allowing Sunlight to enter the indoor space during winter, as it transmits both light and heat like Ordinary glass.
In Mode II (Colored Mode), Prussian Blue (PB) and DHV+• Chemical Species are formed through a Redox (Oxidation -Duction) Reaction, Causing the Window to Turn A Deeep Blue Color. In this state, light is absorbed, and only a purtion of the heat is transmitted, allowing for privacy while enabling approval, indoor temperature control.
Mode III (Colored and Deposation Mode) Involves The Reduction and Deposation of Silver,) Ians on the electrode surface, reflecting bot light and heat. Concurrently, The Colored Material Absorbs The reflected light, effectively blocking glare for external pedestrians.
The research team validated the practical indoor temperature Reduction Effect of the Recm Technology Through Experiments Utilizing A Miniature Model House.
When a conventional glass window was installed, the indoor temperature rose to 58.7 ° C within 45 minutes. Convercely, when recm is operated in mode
Furthermore, Since Each State Transition is achievable soly by electrical Signals, it is Regarded as an active smart technology capable of instantaneous Response According to SEASON, and Intended use.
Professor Hong Chul Moon of Kaist, The Corresponding Author of this study, stated, “This research goes beyond existing smart window technologies limited to visit light control, prescript windy Platform that Comprehensively Considers Not only Active Indoor Thermal Control but also the visual safety of pedestrians.
More information:
Hoy Jung Jo et al, Glare-Free, Energy-Efficient Smart Windows: a pedestrian-friendly system with dynamically tunable light and heat regulation, ACS Energy Letters (2025). Doi: 10.1021/acsenergylet.5c00637
Citation: Three-Mode Smart Window Cut Indoor Temperature By 27 ° C and Eliminal Urban Glare (2025, June 20) retrieved 5 july 2025 from https://techxplore.com/news/2025-06-smart-window-door- temprature.html
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