An Investigation on the Effects of Body Motion, Clothing Design and Environmental Conditions on the Clothing Thermal Insulation by Using a Fabric Manikin

Abstract

The effects of body motion, clothing design and environmental conditions on the thermal insulation of clothing systems were investigated by using a newly developed fabric manikin. The manikin was covered with four typical clothing systems, and the changes of thermal insulation of these clothing systems and the heat lost from the clothed manikin were examined under various walking speeds (0–1.2 km/hr), wind velocities (0–2.2 m/s), and ambient temperature (—20°C–20°C) inside an environmental chamber. Out of this work, better understanding of the reduction of thermal insulation, owing to the combined effects of body motion and wind, are achieved. Also, the work showed the significant effect of ambient temperature on the effective clothing thermal insulation and the advantage of using aluminium foil in the construction of clothing for use in cold environments. Finally, the work revealed the fact that body motion can have a very significant effect on the clothing thermal insulation even though body activity is low. This explains why people, when they feel cold, like to increase their activity level in order to increase heat production rather than reduce their activity level to reduce the heat lost.

Interactions of the surface heat and moisture transfer from the human body under varying climatic conditions and walking speeds

“…Apart from the critical effect of air movement, environmental temperature was found to have considerable effect. Fan and Keighley (1991) reported that the surface insulation in ''still'' air decreases 25% with the environment temperature reducing from 20 to À20 1C. On the other hand, environmental humidity (Meinander et al, 2003), and the size and shape of the body (Kuklane et al, 2004) was found to have little effect on the surface insulation.…”

“…While the surface thermal insulation had been determined by experiments using human subjects or dry manikins (Fan and Keighley, 1991;Olesen et al, 1982), the surface moisture vapor resistance was often estimated from surface thermal insulation based on the Lewis Relation. The validation of this estimation requires a clear understanding on the interaction of heat and moisture transfer at the surface of human body under varying environmental conditions and body motions.…”

Comfort climate evaluation with thermal manikin methods and computer simulation models

“…In warm environments the main mechanism for heat loss is sweat evaporation. An increasing number of manikins in operation can simulate human sweating and provide valuable information about heat exchange by evaporation (Burke et al, 1994, Dozen, 1989, Meinander, 1992, Fan et al, 1991, Lebbin et al, 2003, Burke et al, 2003. …”

“…Another important innovation is the "Walter"-sweating fabric manikin (Fan & Keighley, 1991, Fan, 2003. Walter is equipped with simulation of "walking motion", automated water supply and real time measurement of evaporative water loss.…”

Clothing Thermal Insulation During Sweating

“…It is used to determine the heat stress of a clothed person in a hot environment in terms of the required evaporation for thermal equilibrium, required sweat rate, and skin wetness (ISO 7933 [8], Parsons [ I3]), and to determine cold stress in a cold condition in terms of the required insulation (Holmer [6]). It is also an important measure of the effectiveness of clothing functional design and suitability of clothing systems (Mecheels and Umbach [ I 1 ]) for intended end uses.In the past, there has been considerable research on the effects of human physical activities and climatic conditions, (i.e., wind and surrounding temperature) on clothing thermal insulation (Lotens and Havenith [9], Holmer et al [7], Havenith et al [5], Sari and Berger [14], and Fan and Keighley [3]), but there has been comparatively little work on the effect of human perspiration on insulation. Consequently, clothing thermal insulation measured or predicted in nonperspiring (or dry) conditions is used to calculate the heat transfer through clothing when the body is perspiring (or sweating) with the possibility of error.…”