Physiological aspects of electrically heated garments

Abstract

Inactive man exposed to cold climates and dressed in conventional cold-weather clothing experiences difficulty in maintaining the temperature of the hands and feet. Comfort and performance, especially manual dexterity, are degraded as the temperature of the extremities falls with duration of exposure, and there is also the risk of cold injury. Electrical heating (EH) is a form of auxiliary heating which can offer a solution in some circumstances and is most useful when the wearer can conveniently connect to a power supply of a vehicle or some other type of military equipment. Physiological evaluations and user trials on various types of electrically heated (EH) items including coveralls, gloves, mitts, socks and insoles have been reviewed in this paper, using studies done by the Army Personnel Research Establishment (APRE) as the main source material. Cold-chamber trials showed the effectiveness of EH in maintaining hand temperatures and slowing the fall in foot temperatures even in the extremely cold climate of −32^°C; however, impermeable outers worn over EH gloves, degraded the thermal protection available compared to leather outers. After user trials, whole-body heating in the form of coveralls was judged unnecessary provided that EH hand and foot protection and cold-weather clothing were available. A survey of a number of field trials has been undertaken with a view to extracting general advantages and disadvantages rather than those specific to a particular type of EH equipment. This survey indicated that the user perceived the advantages of EH clothing in terms of increased comfort and manual dexterity; however, users also pointed out disadvantages such as encumbrance, restriction to movement and durability problems. Clearly EH items need to be carefully tailored to the user's requirements and this may incur financial penalties.

Keywords:

• Clothing
• Electrical heating
• Thermal physiology
• Cold