Ultraviolet C-band (UVC) intensity distributions of in duct (ID) ultraviolet germicidal irradiation (UVGI) system were calculated using sophisticated ray-tracing code, RADIANCE, to evaluate the germicidal performance of UVGI system for the surfaces of an air handling unit. And UVC measurements for the same air handling unit were done using UVC sensors to verify the calculated results. However, there were large discrepancies between the both results. Additional experiments to verify the characteristics of sensors and the RADIANCE calculation showed that the results of RADIANCE calculation agreed well with those of illumination measurements but not with UVC intensities and UVC sensors had not been cosine calibrated with UVC wavelength.
