Experimental study on coupling effect of indoor air temperature and radiant temperature on human thermal comfort in non-uniform thermal environment

Abstract

Indoor thermal environment is usually non-uniform in buildings with passive or active radiant surfaces, and strict constraints for thermal homogeneity would increase the difficulty of system design and cause unnecessary energy consumption. In order to explore the thermal comfort response characteristics in non-uniform environments, 20 subjects were recruited in this study to participate in a thermal comfort experiment in two types of non-uniform environments. The two non-uniform environments were created by different combinations of indoor air temperature and radiant temperature. In the first non-uniform environment, all the interior surface temperatures were equal, but the radiant temperature and air temperature were not equal (ANUE). The other type was a single surface non-uniform environment where the surface temperature of one interior surface and the air temperature were not equal (SNUE). Subjects’ physiological parameters were measured and subjective evaluations were obtained by questionnaires. The results showed that in thermal neutral condition, the mean skin temperature was 33.6 °C under ANUE environment, while it was 33.8°C–33.9 °C under SNUE environment. Based on the experimental results, thermal dissatisfied percentage (TDP) models for the two environments were proposed and evaluated by determination coefficient and Bayesian information criterion (BIC). According to the five different TDP levels (5%, 10%, 15%, 20%, 25%), coupling thermal comfort zone of indoor air temperature and surface temperature was classified into five hierarchies. The study has implications for the proper design of comfortable and energy saving non-uniform environments.