Researchers from the Korea Advanced Institute of Science and Technology (KAIST) have developed a "smart window" that blocks light pollution and heat. It is expected to contribute to energy savings as it can be applied to both buildings and vehicles.
Professor Moon Hong-cheol's research team at KAIST's Department of Bio and Chemical Engineering has announced on the 17th that they have developed "smart window technology" that controls light and heat coming through windows and effectively offsets glare from outside.
The next-generation smart window technology developed by the research team, called "RECM," is a smart window system that actively adjusts the transmittance of visible light (light) and near-infrared (heat) based on electrochromic elements. The existing metal deposition method for smart windows had significant glare due to reflected light. The smart window created by the research team uses chromatic materials to suppress the glare.
The RECM system can be used in three modes depending on voltage control. Mode I (transparent mode) allows light and heat to pass through like regular glass, making it advantageous for bringing sunlight indoors during winter. In Mode II (chromatic mode), the window changes to a deep blue color through a redox reaction (oxidation-reduction reaction). In this state, light is absorbed and only some heat is transmitted, enabling privacy protection while maintaining appropriate indoor temperature control.
Mode III (chromatic and deposition mode) allows silver ions to deposit on the electrode surface through reduction reactions, reflecting both light and heat, while the chromatic material absorbs reflected light, effectively blocking glare from external pedestrians.
The research team verified the practical indoor temperature reduction effect of the RECM technology through experiments using miniature model houses. In the case of using regular glass windows, the indoor temperature rose to 58.7 degrees Celsius in just 45 minutes. In contrast, when operating RECM in Mode III, the temperature dropped to 31.5 degrees.
Professor Moon Hong-cheol noted, "This research presents a true smart window platform that comprehensively considers not only active indoor heat control but also the safety of pedestrians' vision, going beyond the existing smart window technology limited to visible light control." He added, "There are various application possibilities expected from urban buildings to vehicles and trains."
References
ACS Energy Letters (2025), DOI : https://doi.org/10.1021/acsenergylett.5c00637