2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
Figure 1. Five test garments, consisting of combinations of water-vapour permeable (dark
colour) and impermeable (light colour) fleeces (made of polyester).
Eight young males (Caucasian, 22.4 ±4.2 y, 178.8 ±6.2 cm, 74.7 ±8.8 kg) participated in the
test. The experiment was performed at 22°C with 50 %RH (10 mmHg) for 65 min. In the first
15 min, the subject rested condition, with 0.1 m·sec -1 of air-flow, and then exercised, walking
on a treadmill with a speed of 4.5 km·hr- 1 , at 0.2 m·sec -1 of air velocity. Temperatures of ear
canal, skin surface of 8 sites including the target locations, and dew point in the target 4
locations was measured continuously. Thermal comfort sensations in the whole body and
individual target location were also voted using 7-point scale (3: very comfortable, 2:
comfortable, 1: slightly comfortable, 0: neutral, -1: slightly uncomfortable, -2: uncomfortable,
-3: very uncomfortable).
RESULTS
We first confirmed that the target values for mean weighted skin wettednesses were obtained,
because there were no statistical differences among test garments, while the skin wettedness
in individual target location was remarkably larger than the observed in the rest of the body.
Thermal comfort sensation and skin wettedness in the whole body were plotted against the
temperature of ear canal (Figure 2). The skin wettedness remained stable at a level of
approximately 0.15 during the rest condition. On the other hand, considerable increase in the
skin wettedness was observed for the ear canal temperatures above 36.2-36.4°C. This is due
to the sweating accompanying exercise. The subjects felt slightly comfortable when their ear
canal temperatures were lower than ~36.2°C. With further increasing the ear canal
temperature and the skin wettedness, the thermal comfort sensation tended gradually towards
discomfort. According to the results, the thermal comfort limit for the whole body was found
to be about 0.35 (Figure 2). Furthermore, the subjects claim thermal discomfort in the whole
body when their ear canal temperature attained 36.4-36.6°C, irrespective of the local comfort
sensation.
Local thermal comfort sensation was plotted for the tested target locations (Figure 3), with the
abscissa indicating skin wettedness at which the thermal comfort (ordinate) was voted for the
372
Control
Type A
Type B
Type C
Type D