Mitigating impacts of hot weather on outdoor workers by attaching phase change materials based on body mapping of physiology

Abstract

To effectively mitigate impacts of hot weather on outdoor workers and improve their thermal comfort and work efficiency, a novel cooling vest (CV) with phase change material (PCM) was developed. The originality of this CV lies in the distribution of PCM packages which are totally based on body mapping of thermal sensation and perspiration. Human tests were performed in a climate chamber simulating hot outdoor environment (35 °C, 55 %RH) to evaluate thermal and movement comfort of workers wearing this CV. The results showed that skin temperature (T_sk) of each localized area was significantly (p < 0.05) reduced by 3.90–9.00 °C compared to that without CV. Besides, a great advancement compared to previous research is the cooling effect could last for the entire 2 h. Subjective thermal sensation was improved from hot (+3) to slightly warm (+1). Pearson correlation analysis revealed T_sk of back and scapula had the strongest correlation (p < 0.01, r > 0.8) with local and overall thermal sensation vote (TSV), indicating cooling these two body parts would achieve a more certain decreased TSV compared to cooling other body parts. Meanwhile, the self-perceived level of fatigue by subjects was lowered because of the improved thermal comfort. This newly developed CV managed to effectively improve both the thermal comfort and work efficiency of outdoor workers without adding extra load. This study provides new technology with physiological and ergonomic basis for creating thermally comfortable near-body environment for workers who have to be exposed to hot environment.