Energetic comparison of the inactivation of airborne corona viruses using UVC radiation or a conventional HEPA filter in an air purification unit

• experimental evaluation of the air disinfection with UVC radiation with real virus loaded aerosols • evaluation of the radiation dose with CFD simulation • validation of the radiation distribution in the UVC chamber • evaluation of the necessary UVC dose for aerolized corona viruses • energetic comparison to conventional filters During the COVID-19 pandemic, decentralized air purification units have been widely used to reduce airborne infection risks in indoor environments. While both high-efficiency particulate air (HEPA) filtration and ultraviolet C (UVC) irradiation are effective for removing or inactivating airborne viruses, their energetic performance has not yet been systematically compared. Building on previously published experimental measurements of airborne coronavirus (FCoV) inactivation using UVC-LED radiation and filtration in a portable air cleaner, this study evaluates the associated electrical energy demand of both technologies. The experimental results are complemented by computational fluid dynamics (CFD) simulations to determine particle residence times and irradiation dosages within the UVC chamber, as well as analytical modelling of room-scale air purification performance. The results show that, under the investigated conditions, UVC irradiation using low-efficiency LEDs (4.5 %) requires significantly higher electrical power than HEPA filtration to achieve comparable virus reduction. At the reference operating point, the energy demand for UVC-based inactivation exceeds that of filtration by up to a factor of 94. However, the analysis also demonstrates that this relationship strongly depends on key parameters, particularly the efficiency of the UVC source and the geometric design of the irradiation chamber. A parametric evaluation indicates that with improved LED efficiencies and optimized chamber configurations, the energetic gap between UVC irradiation and filtration can be substantially reduced. The results highlight the importance of considering both disinfection performance and energy demand when designing air purification systems and provide a framework for evaluating future UVC-based technologies in building applications.