Tungsten oxide (WO 3) photochromic film for smart windows faces many challenges, including slight discoloration, and slow and irreversible photochromic response. We propose a WO 3 quantum dots (WQDs) to resolve the above problems, and WQDs-polyvinyl alcohol (PVA) transparent film by casting method exhibits quick response to ultraviolet light (<60 s), and large optical modulation (>90%) between bleached and colored states, although the bleaching time is still long (8 h). Meanwhile, the PVA/WQDs composite film is self-supported and exhibits excellent tensile properties. The actual cooling effect of the photochromic glass was tested using a model house and the annual energy consumption was simulated by using EnergyPlus software. For a warm city (Haikou), using this photochromic glass can reduce electrical consumption for cooling by 27.3%. • The PVA/WQDs film by casting method exhibits quick response to ultraviolet light (<60 s), large optical modulation (>90 %) between bleached and colored states, although the bleaching time is still long (8 h). • The actual cooling effect was tested using a model house. • The annual energy consumption was simulated by using EnergyPlus software. [ABSTRACT FROM AUTHOR]