Clothing heat exchange models for research and application

The regulated exchange of heat from the human body to the environment is essential in human survival. This exchange is adjusted by our physiological response mechanisms. We are able to sweat profusely to cool the body in exercise and heat exposure, and are able to fine-tune our body temperatures in moderate environments through variations in skin circulation. In slightly cool environments, we reduce blood flow to our extremities and skin and use our fat layer insulation to conserve central body temperature. We can increase our heat production by shivering and can create a small insulating air layer around our skin by pilo-erection. However, when temperature goes down further, we cannot sustain our body temperature in the long run without behavioural adjustments that include putting on clothing or using heated dwellings. In this context, clothing has allowed mankind to expand its habitat around the world and has had a positive influence on its development. Today, clothing is worn for various reasons. Apart from its functional aspects (insulation, protection), it has a strong cultural and social aspect as well. The latter are on occasion counterproductive in terms of the first. A business suit for instance is hardly functional in a tropical climate, nor is a ladies evening dress in a cold environment. Also, when the function of the clothing is not only protection against heat or cold, as e.g. is the case with chemical protective clothing, the barriers introduced in the clothing to achieve the required protection can cause a conflict between the protective function of the clothing and the thermal functioning of the body. These conflicts can lead to discomfort, but also to physical strain and in extreme cases can put the person at risk from heat or cold injury or illness.