Thermal comfort under asymmetric cold radiant environment at different exposure distances

Abstract

Radiator heating (RH) and floor heating (FH) exhibit disparate indoor asymmetric environments. In addition, the indoor microenvironment at different locations remarkably varies owing to the cold radiation generated by the surface of exterior walls and windows (EWWs) in winter in the severe cold region of China. The impacts of the exposure distance from the cold radiation on human thermal comfort should be addressed. In this study, an experiment was conducted in a controlled climate chamber, and 66 college students were recruited as volunteers to investigate their physical and psychological responses. The mean radiant temperature (MRT) and the radiant temperature asymmetry (△tpr) were used to assess the environment. The results indicated that compared to MRT in the FH, that in the RH is closer to the ambient air temperature. The horizontal and vertical radiant asymmetries concurrently affected the RH system in the chamber, whereas only the vertical asymmetry played a crucial role in the FH environment. Among the physiological responses, the skin temperature and the heart rate significantly decreased as the distance from the EWWs was reduced in the RH environment, whereas the blood pressure demonstrated no remarkable difference. When the subjects were in comfortable but non-uniform environments, the thermal acceptability was affected by the thermal sensation of multiple local body parts. In a slightly cold environment, the limit of the vertical radiant asymmetric temperature in the FH was 3.6 °C. The experimental results of this study can serve as a reference for thermal designs of buildings.