Humidity‐Controlled Smart Window with Synchronous Solar and Thermal Radiation Regulation

Abstract Dynamic and continuous regulation of both solar and thermal radiation through windows is critical for enhancing building energy efficiency. However, achieving such adaptive regulations within a single window remains a formidable challenge. In this study, a humidity‐responsive polytetrafluoroethylene (PTFE)/ polyvinyl alcohol (PVA) composite membrane is developed with a nanoporous structure and integrated between two layers of glass to engineer a humidity‐controlled smart window. By modulating the humidity level between the glass layers, the smart window enables the dynamic and coordinated modulation of solar and thermal radiation via the reversible adsorption and desorption of water vapor by the PTFE/PVA composite. The results indicate that the humidity‐controlled smart window demonstrates superior capabilities in solar modulation (54.4%) and thermal radiation modulation (51.4%). Statistical analysis reveals that compared to ordinary windows and low emissivity (Low‐E) windows, PTFE/PVA windows reduce total annual energy consumption by ≈25% and 40%, respectively. This broadband dynamic continuous regulation mechanism may offer groundbreaking insights into the advancement of smart window technologies.