Investigation based on physiological parameters of human thermal sensation and comfort zone on indoor solar radiation conditions in summer

Abstract

Indoor solar radiation significantly affects human thermal sensation, especially with the extensive use of glass structures in modern buildings. This study explored the varying characteristics of human physiological and psychological responses to indoor solar radiation in the summer, based on a laboratory experiment involving 20 participants and six cases comprising different intensity levels and irradiation areas. In this experiment, the thermal sensation and acceptability were recorded, and environmental and physiological parameters such as local skin temperature, arterial oxygen saturation (SpO2) and pulse rate (PR) were continuously monitored. The results revealed that human physiological regulation is generally delayed, as compared with the psychological changes in unstable environments. This paper proposes a method for calculating the mean skin temperature, representing the skin temperature on the irradiated side by that on the nonirradiated side. The skin temperature calculated using this method reflected the strongest correlation with thermal sensation; this helped reduce the prediction errors in thermal sensation due to psychological factors, when considering skin temperature as a predictor. Furthermore, this study used the standard effective temperature (SET) to calculate acceptable temperature ranges and a neutral SET. It was found that the neutral SET exceeded the general indoor environment by approximately 1 °C; the upper limit of acceptable temperature was 1.77 °C higher than that recommended in ISO 7730, indicating humans' enhanced acceptance ability to air temperatures under indoor solar radiation. Notably, the results of this study constitute a significant theoretical basis for improving thermal comfort under indoor solar radiation in the summer.