Fast‐Responding Thermal Hydrogel Smart Windows for Energy‐Efficient Buildings

ABSTRACT

To achieve energy savings in buildings, thermochromic hydrogel smart windows have been proposed and widely applied. However, the response speed of the current temperature‐driven mechanism based on non‐radiative heat transfer tends to be relatively slow, resulting in mode response delays and consequently reducing energy‐saving potential. In this study, we propose a strategy to improve the response speed of the hydrogel window by additionally and selectively absorbing near‐infrared light via incorporating Cesium‐doped tungsten oxide nanoparticles. By enabling a synergistic response to both ambient temperature and solar irradiation, the delay time in the mode transition of the window is successfully reduced. Experimental results show that the smart window effectively responds to both temperature and solar radiation without compromising its ability to modulate visible light. In Sydney, year‐round analysis further demonstrates an absolute improvement of 29.5% in the response accuracy of the smart window, significantly enhancing its energy‐saving performance. The smart window achieves an annual energy‐saving rate of 26.1%, exhibiting an absolute improvement of 18.6% compared to conventional hydrogel windows.