Modeling of Human Thermal Regulation in the Room for Local Exposure to Solar Radiation

Human thermal regulation models reflect the physiological response of the human body to the surrounding thermal environment. However, existing thermal regulation models do not account for the non-uniform impact of solar radiation on indoor thermal environments and the human body. Therefore, a new model was established by modifying the thermal regulation model of the human body to include local exposure to direct sunlight in buildings. First, the calculation of mean radiant temperature was revised by distinguishing direct and indirect areas. Second, the calculations of skin and clothing temperatures and heat loss in the model were modified by distinguishing direct and indirect parts. In addition, solar radiation heat gain was added to the heat transfer calculations. After experimental verification, the modified model demonstrated a relative error of less than 5% in predicting mean skin temperature, and approximately 4% in predicting total heat loss. Using the model, the mean skin temperature at different activity levels was predicted, and the thermal comfort zone offset laws of the human body as a whole and in direct parts were explored at different solar radiation intensities. The results show that the acceptable air temperature of the overall body at 400 W/m² is 2 ℃ lower than that at 200 W/m². This study provides a theoretical basis for zoning control of indoor environments under direct sunlight.