Tri-band smart window envelope based on temperature adaptive kirigami structure

Regulating thermal radiation exchange between windows and the environment is crucial for building energy efficiency. While traditional low-emissivity (Low-E) windows and emerging smart windows offer promising solutions, they face challenges in adapting to complex changes in temperature and light conditions. In this paper, we introduce a temperature-adaptive radiator with a kirigami structure (TARK) window envelope, which integrates a vanadium dioxide (VO₂) based Fabry-Pérot (F-P) cavity with an angle-adjustable kirigami structure. This design enables temperature-adaptive solar modulation and angle-adjustable thermal radiation, addressing the limitations of conventional approaches. Specifically, the TARK achieves 31.10% solar modulation (Δ<i>T</i>_SOL), 0.96 mid-infrared emissivity (<i>ε</i>_MIR) at high temperatures, and 0.63 mid-infrared modulation (Δ<i>ε</i>_MIR) with angle-adjustable radiation capabilities. Experimental validation under indoor and outdoor conditions confirms its directional radiation performance and robustness across diverse weather scenarios. Moreover, the device demonstrates up to 25.3% savings in HVAC energy consumption compared to glass, highlighting its potential for significant energy savings in building applications. This work advances the development of next-generation smart window technologies by combining materials science, structural engineering, and environmental adaptability.