**Professor Moon Hong-chul’s Bio-Chemical Engineering Team**
“Expected Applications in Architecture and Transportation”
The photo shows Jo Hye-jeong (left), a master’s student at the Department of Chemical Engineering at Seoul City University, and Professor Moon Hong-chul of the Department of Bio-Chemical Engineering at KAIST, who developed ‘smart window technology’ [provided by KAIST].
In the building sector, which accounts for about 40% of global energy consumption, heat ingress through windows has been identified as a major cause of heating and cooling energy waste.
KAIST announced on the 17th that Professor Moon Hong-chul’s research team in the Department of Bio-Chemical Engineering has developed ‘smart window technology’ that adjusts the light and heat entering through the windows according to the user’s intent and effectively offsets glare from the outside.
Recently, ‘active smart window’ technology, which allows users to freely control light and heat, has gained attention. The next-generation smart window technology developed by the research team, RECM, is an active smart window system that can adjust the transmittance of visible light and near-infrared light based on a single-structure electrochromic device.
In particular, it implemented a ‘pedestrian-friendly smart window’ applicable to building exteriors by effectively suppressing glare caused by reflected external light, which has been pointed out as an issue in existing metal deposition-type smart windows, by applying a discoloration material together.
The RECM system developed in this study operates in three modes depending on voltage regulation. Mode I (transparent mode) allows both light and heat to pass through like ordinary glass, advantageous for letting sunlight into a room during winter.
In Mode II (discoloration mode), the window changes to a deep blue through a redox reaction (oxidation-reduction reaction). In this state, light is absorbed, and only some heat transmits, enabling privacy and appropriate indoor temperature control.
Mode III (discoloration and deposition mode) involves silver (Ag+) ions depositing on the electrode surface through a reduction reaction, reflecting light and heat, while the discoloration material absorbs reflected light, effectively blocking glare for external pedestrians.
The research team verified the practical indoor temperature reduction effect of the RECM technology through experiments using a miniature model house. With ordinary glass windows, the indoor temperature rose to 58.7 degrees in just 45 minutes. However, when RECM was operated in Mode III, the temperature reached 31.5 degrees, demonstrating a temperature reduction effect of about 27.2 degrees.
Professor Moon said, “This study presents a truly smart window platform that comprehensively considers active indoor heat control and pedestrian visual safety, beyond the existing smart window technology limited to visible light control,” and added, “It is expected to have various applications from urban buildings to vehicles and trains.”
The research results were published on the 13th in ‘ACS Energy Letters,’ a prestigious international journal in the field of energy. By Koo Bon-hyuk