Interaction of clothing and thermoregulation

Human temperature regulation is based upon a physiological system 'designed' for a naked person. Hence, the statement 'man is a tropical animal'. Human thermoregulation can be described as a feedback system with sensors in the body core and the skin, and effectors in the form of skin blood flow (vasoconstriction and dilation), metabolic activity (shivering), pilo-erection and sweating. This system on its own would provide some adjustment capabilities to various environments, but would nevertheless limit man to life in warm environments. It is the behavioural response that is the most powerful additional thermoregulatory effector in humans. People wear clothing, live in houses and have active heating and cooling systems to expand their habitat beyond the original physiological limits. Clothing is an important interface between the human and the environment. Apart from the cultural meaning of clothing it provides insulation against cold, protection against the sun, wind or rain as well as protection from other environmental hazards (chemicals, mechanical). The effect of clothing on thermoregulation depends in the first place on the textile materials used. These provide thermal insulation as well as resistance against vapour (sweat) transfer. However, a garment is more than just the textile layer. Air layers included in the clothing provide additional insulation and the total thermal protection provided by a garment is for a large part based on these enclosed air layers and strongly influenced by the clothing design and fit. Clothing comfort is determined by a number of clothing properties that affect the thermal conditions at the skin. Skin temperatures and the tactile sensation of the skin (e.g. sticky moist clothing) are the main signals that are fed to the brain and lead to an overall sensation of comfort or discomfort.