Electrochromic smart windows (ESWs) can significantly reduce building energy consumption, but the high cost hinders large-scale production. The in-situ growth tungsten oxide (WO₃) films only by a simple immersion process, the silver nanowires (AgNWs) undergo oxidation to Ag⁺ through electron loss and the liberated electrons provide driving force for the deposition of WO₄^2-. Enabled the fabrication of large-area WO₃ films and ESWs were fabricated under minimal laboratory conditions, demonstrating the economic feasibility, efficient and reliable nature of industrial production. Structural characterization and DFT calculations were combined to confirm that AgNWs effectively regulate oxygen vacancies of WO₃ films and promote the in-situ growth process. The optimized WO₃ exhibits a maximum transmittance modulation of 90.8% and excellent cycling stability of 20,000 cycles. The large-scale WO₃-based ESWs can save building energy up to 140.0 MJ m^-2 compared to traditional windows in tropical regions, as verified by simulations more than 40 global cities. This research provides a new approach for improving the performance and industrial production of ESW, providing the full understanding and development direction to short the distance of the ESW commercial production.

Electrochromic,Smart window,Tungsten oxide,Large area