Moisture accumulation in sleeping bags at − 7°C and − 20°C in relation to cover material and method of use

Abstract

Moisture accumulation in sleeping bags during extended periods of use is detrimental to thermal comfort of the sleeper, and in extreme cases may lead to sleep loss and hypothermia. As sub-zero temperatures were expected to affect vapour resistance of microporous membranes, the effect of using semipermeable and impermeable rain covers for sleeping bags on the accumulation of moisture in the bags during six days of use at -7 and five days at -20 ºC were investigated. In addition, the routine of shaking off hoarfrost from the inside of the cover after the sleep period as a preventive measure for moisture accumulation was studied. Moisture accumulation (ranging from 92 to 800 grams) was found to be related to the vapour resistance of the materials used. The best semipermeable material gave the same moisture build-up as no cover at -7ºC, though build-up increased substantially at -20ºC. Shaking off the hoarfrost from the inside of the cover after each use was beneficial in preventing a high moisture build-up. It was concluded that semipermeable cover materials reduce moisture accumulation in sleeping bags at moderate sub-zero temperatures, but in more extreme cold (-20ºC) the benefits are reduced in comparison to routinely shaking frost from impermeable covers. Compared to fixed impermeable covers, the benefits of all semipermeable covers are large. For long-term use without drying facilities, the differences observed do favour the semi-permeable covers above impermeable ones, even when regularly removing the hoar frost from the inside in the latter.

Evaporative cooling: effective latent heat of evaporation in relation to evaporation distance from the skin

“…1). There, it may be sorbed and subsequently desorbed by textile fibers (11); it may condensate in outer layers if these are colder than the skin (14,15,16,17,18,24) and subsequently evaporate again. It may be directly ventilated from the clothing microclimate through openings in the clothing or may finally diffuse through the outer clothing layer into the environment.…”

Study of heat and moisture transfer within multi-layer clothing assemblies consisting of different types of battings

“…absorption or condensation) within clothing is a serious problem for sportswear and clothing worn in cold climate [1][2][3][4][5]. As the wearer stops the exercise and his metabolic heat production reduces, the reduction of clothing thermal insulation due to condensates within clothing and the heat absorption by the moisture de-sorption re-evaporation of the condensates will cause "chilling" discomfort or even hypothermia.…”

Mathematical modeling and numerical simulation of heat and moisture transfer in a porous textile medium

“…Email: mancusi@unisannio.it moisture accumulation due to absorption or condensation within clothing is a serious problem also for sportswear (e.g. Berger & Sari, 2000;Ghaddar, Ghali, & Jones, 2003;Havenith, Hartog, & Heus, 2004;Lotens & Havenith, 1995). As the sportsman stops the exercises his metabolic heat production drastically reduces, the reduction of clothing thermal insulation due to condensates within clothing and the heat absorption by the moisture de-sorption re-evaporation of the condensates will cause "chilling" discomfort or even hypothermia (e.g.…”