Optimization of thermochromic photovoltaic windows for multiple building performance

Solar energy utilization is critical for improving the building energy performance of building windows. This study evaluates the comprehensive building performance of thermochromic (TC) photovoltaic (PV) windows under different photovoltaic etching rates and transition temperatures, with four etching levels of 20%, 40%, 60%, and 80% and three transition temperature levels of 25 °C, 35 °C, and 45 °C adopted for parametric analysis. Six typical cities, including London, Beijing, Dubai, Hong Kong, Singapore and Harbin are selected for multi-climate performance evaluation. The results indicate that the net energy variation ratio relative to regular windows of the proposed windows ranges from −34.48% (PV 40%-TC 35 °C, Dubai) to ~ +48.65% (PV 20%-TC 25 °C, Singapore), where negative values indicate energy savings. Compared with thermochromic windows, integrating PV glazing can further reduce net energy consumption by up to 32.27%. The window exhibits a color rendering index of 98.7–99.4, while the optimal configurations reduce annual glare hours by 2.43% ~ 13.05%, although annual standard illuminance hours decrease by 11.00% ~ 22.26%. Analysis of meteorological parameters shows that the net energy-saving potential does not exhibit a simple monotonic relationship with local solar radiation or outdoor temperature, as the final performance is jointly affected by heat transfer, daylighting, and PV power generation. The economic analysis further shows clear climate-dependent differences in the payback potential of thermochromic photovoltaic windows. This study provides data and technical references to support the climate-adaptive design and application of energy-efficient building windows.