Self-sustained solar-driven airborne bacterial inactivation via thermal-UV synergistic inactivation in BIPVT systems

In the context of increasing demands for both indoor health and building energy efficiency, building energy systems integrating solar heating and photovoltaic power generation with air purification show great potential. Incorporating UV inactivation can further enhance disinfection performance. However, in solar utilization systems, air temperature typically falls within a moderate range (40–60°C), and the thermal-UV synergistic inactivation of bioaerosols under such conditions remains insufficiently understood. This study systematically investigates the quantitative thermal-UV synergistic inactivation characteristics of airborne bacteria under different UV peak wavelengths and further develops two self-powered, self-purifying building envelopes. A sealed experimental chamber was constructed to measure the inactivation rate of aerosolized Escherichia coli and Staphylococcus aureus under different UV peak wavelengths (222, 254, and 365 nm) and temperatures (25–60°C). Results show that thermal and UV irradiation exhibit a synergistic inactivation effect at 222 nm and 254 nm. A four-parameter inactivation model was developed and shows good agreement with experimental results. System-level analysis indicates that incorporating UV inactivation significantly improves bioaerosol removal, increasing the daily clean air delivery for E. coli and S. aureus by approximately 2.17 and 5.27 times, respectively. Parametric analysis shows that increasing air channel depth benefits the air purification performance of the system. The findings provide new insights into solar-driven bioaerosol control. Moreover, the established thermal-UV inactivation model can be further extended to air-handling systems such as HVAC systems and heat-recovery ventilation units, offering theoretical support for improving indoor air quality.