Experimental study on local floor heating mats to improve thermal comfort of workers in cold environments

Abstract

This study investigates the effect of local floor heating mats on the thermal comfort of workers in cold environments. Experiments were performed with two sizes of floor heating mats under two power input levels. Twenty subjects participated in the experiments at three air temperature conditions of 11, 13, and 15 °C. The participants performed three activities in the experiments: sitting, sitting + packing, and standing + packing. Subjective questionnaires were collected, including the overall thermal sensation vote (TSV), local thermal sensation of feet (TSVfeet), and thermal comfort vote (TCV). The subjects’ mean skin temperature (MST) and cochlear temperature were measured. The results show that subjects' TSV, TSVfeet, and TCV significantly improved when using heating mats of larger size and higher power input. TSVfeet increased faster than TSV. When the air temperature decreases, TSVfeet should be higher to keep TSV close to neutral. Moreover, subjects' MST and cochlear temperature also increased slightly when heating mats were adopted. Both MST and cochlear temperature were positively correlated with TSV. Heating mats also increased the subjects' working efficiency, related to the TSV and TCV. Analysis of the vertical temperature distribution in the vicinity of the subjects showed that with heating mats, the thermal plume was enhanced, and the ambient air temperature increased slightly. Hence, local floor heating mats can effectively improve the thermal comfort and working efficiency of workers in cold environments.