Multispectral Synergistic Electrochromic Regulator With Triple Atmospheric Windows Selectivity for Global Building Energy Saving

ABSTRACT As a growing contributor to global energy demand, building energy consumption is strongly constrained by the passive nature of conventional opaque building envelopes. Here, we design a tunable multispectral regulator based on an ITO/WO 3 /LiNbO 3 /NiO/ITO electrochromic all‐thin‐film stack. Through the ingenious device architecture of an asymmetric Fabry–Pérot cavity (F–P cavity), the regulator achieves multispectral positive synergistic modulation: in the cooling mode, it simultaneously reflects sunlight and exhibits selective high emissivity within the atmospheric windows; in the heating mode, it absorbs sunlight while maintaining low infrared emissivity. This design also extends effective modulation to the third atmospheric window (16–25 µm). Consequently, the device delivers synergistic and wide modulation with values of 0.52 and 0.64 in the solar (0.3–2.5 µm) and mid‑far infrared (2.5–25 µm) bands, respectively, enabling both summer cooling and winter heating. Outdoor testing in an arid desert climate validates effective thermal regulation, achieving a diurnal temperature difference of ∼5.5°C. With its adaptive regulation capability, the device is well‐suited for year‑round building energy saving. EnergyPlus simulations further reveal substantial annual energy savings, particularly for heating in cold regions (22.2 MJ/m 2 ). This work provides a monolithic tunable platform for synchronized multispectra regulation, paving the way for next‑generation intelligent thermal management systems.