Dual‐Responsive Thermochromic Smart Windows With Integrated Solar‐Thermal Regulation and Thermoelectric Energy Harvesting

Buildings account for 30%–40% of global energy consumption, a substantial fraction of which is associated with heat transfer through conventional windows. Although window technologies have advanced considerably, most existing solutions still rely on passive operation or cumbersome designs that compromise transparency. Here, we report a smart window that combines thermal regulation with thermoelectric energy harvesting. The system integrates two hydrogel layers: one undergoes dual‐phase transitions at 16°C and 32°C to enable temperature‐responsive optical switching, while the other provides thermoelectric functionality. The window maintains over 90% transparency between these transition temperatures, but turns opaque above and below them, thereby affording effective thermal insulation under both hot and cold conditions. At the same time, it delivers a power density of 0.191 W/m 2 under a 10 K temperature differential between the exterior and interior surfaces. This work provides a physically decoupled strategy for combining dynamic optical regulation and thermoelectric energy harvesting in transparent smart windows, highlighting their potential for next‐generation multifunctional building envelopes.