Submicron Metasurface Reconfigured Multiband Smart Windows

Improving the energy efficiency of windows holds great significance for global carbon emission reduction. Multiband thermochromic smart windows (MTSWs) based on vanadium dioxide (VO₂), which dynamically modulate indoor solar irradiation (ΔT_sol) and outdoor long-wave heat radiation (Δε_LWIR), offer a promising pathway for passive building thermoregulation. However, limited by the intrinsic properties of materials and the complexity of multilayer architectures, current designs severely jeopardize luminous transmittance (T_lum) when pursuing high regulation capabilities. Given that artificial lighting constitutes 17.4% of building electricity consumption, this trade-off critically compromises their net energy-saving potential. Here, we propose a submicron metasurface reconfigured MTSW (Meta-MTSW), fabricated via template-assisted nanoimprinting, to break this bottleneck by coupling subwavelength nanostructures. Theoretical and experimental analyses reveal that the gradient profile acts as an impedance-matching layer to minimize the Fresnel reflection in the visible and near-infrared bands without disrupting the Fabry−Perot resonance in the long-wave infrared band. Consequently, Meta-MTSWs enhance T_lum by 60.1% compared to the state-of-the-art reference, while maintaining uncompromised ΔT_sol and Δε_LWIR. Comprehensive building energy simulations across eight climate zones demonstrate that Meta-MTSWs yield substantial reductions in annual energy consumption by up to 15.9% compared to commercial low-emissivity glass, validating this nanoengineering paradigm as a compelling pathway for climate-adaptive sustainable architecture.