Incorporating Shading Effects into a View Factor Model for Predicting Ultraviolet Disinfection Efficacy in Indoor Environments

• A method for calculating UV shading effects based on view factors was developed. • The developed method was validated by experimental measurements. • Ignoring shading effects can lead to an overestimation of UV disinfection efficacy. Indoor bioaerosols present a significant risk to human health, contributing to the transmission of respiratory and infectious diseases. Ultraviolet (UV) radiation has emerged as a widely used approach for controlling indoor bioaerosols. Simulation-based design provides a powerful approach for predicting the disinfection effectiveness of UV radiation. A critical prerequisite for simulations is the accurate calculation of the UV irradiance distribution. However, the widely used view factor method falls short in accounting for the occlusion of UV radiation by irregular objects, which can lead to an overestimation of the effectiveness of UV disinfection. To address this limitation, this study proposed an improved view factor method that incorporated UV shading effects. The proposed method was first validated in a full-scale chamber equipped with a heated manikin and a table. The calculated UV irradiance distribution and bioaerosol concentrations were compared against experimental measurements. Results showed that our method successfully predicted the UV shading effects caused by irregular objects and the variations in bioaerosol concentrations. The method was subsequently applied to a shared office case to demonstrate the importance of accounting for shading effects in the calculations. Results revealed that neglecting the shading effect overestimated the UV disinfection efficiency by a factor of 1.3–2.4 in calculation. By incorporating shading effects into calculations, the method delivered more reliable UV dose predictions, enabling safe and accurate design of indoor UV systems while mitigating occupant exposure risks of bioaerosols.