Impact of metabolic rate on human response to air movements during work in cool environments

The impact of metabolic rate on human sensitivity to draught was studied in a series of laboratory experiments. Ten male subjects were exposed to mean air velocities increased step-by-step ranging from 0.05 m · s^-1 to 0.40 m · s^-1 at air temperatures of 11, 14, 17 and 20°C, while performing standing physical work at two different activity levels (104 W · m^-2 and 129 W · m^-2). The subjects were asked whether they could feel an air movement, whether it was uncomfortable and where it was felt. The neck was identified as the most draught sensitive area, and draught was most often felt at the head region comprising neck, face and upper back. At the uncovered regions of the hands and face an influence of air temperature on local draught ratings was seen whereas the percentage of dissatisfied due to draught at the head region did not depend on the air temperature. The results showed that working at a high activity level resulted in fewer dissatisfied due to draught, as compared to a low activity level. It was concluded that the metabolic rate, equivalent to the internal heat production, significantly influenced human response to air movements for standing activity in a cool environment.

The impact of metabolic rate on human sensitivity to draught was studied in a series of laboratory experiments. Ten male subjects were exposed to mean air velocities increased step-by-step ranging from 0.05 m · s^-1 to 0.40 m · s^-1 at air temperatures of 11, 14, 17 and 20°C, while performing standing physical work at two different activity levels (104 W · m^-2 and 129 W · m^-2). The subjects were asked whether they could feel an air movement, whether it was uncomfortable and where it was felt. The neck was identified as the most draught sensitive area, and draught was most often felt at the head region comprising neck, face and upper back. At the uncovered regions of the hands and face an influence of air temperature on local draught ratings was seen whereas the percentage of dissatisfied due to draught at the head region did not depend on the air temperature. The results showed that working at a high activity level resulted in fewer dissatisfied due to draught, as compared to a low activity level. It was concluded that the metabolic rate, equivalent to the internal heat production, significantly influenced human response to air movements for standing activity in a cool environment. Relevance to industry. Draught, defined as an unwanted, local cooling of the skin caused by air movements, is a common cause of complaints among employees working in cool or cold industrial spaces. No studies are available that investigate draught sensitivity for persons performing manual work. In this paper, the effect of workload (metabolic rate) on human sensitivity to draught is studied with subjects working in a cool environment.