In this study, the effect of radiation heat flux from lighting lamps on human thermal comfort was investigated by both experimental and theoretical approaches. The experiments were carried out in an air-conditioned laboratory room in both the summer and autumn seasons. To determine the thermal response of a human body exposed to radiation heat flux from lighting lamps, a simulation model based on the Gagge model with some modifications was developed, and the effect of radiation heat flux from lighting lamps on human thermal comfort was investigated under transient conditions. The human body was separated into 16 sedentary segments, and the change in temperature was observed both experimentally and theoretically. During transient conditions, heat and mass transfer between the human body and the interior environment of a climate chamber were simulated using a computational model, and predictions were compared to the measured data. It is observed that there is a good agreement between the model predictions and experimental results. (C) 2015 Elsevier B.V. All rights reserved.