Heat management

An interesting development is the use of "phase change" materials. These materials use the energy changes involved in latent heat of melting/freezing of encapsulated hydrocarbons to store and release energy. As the temperature rises heat is stored and as the temperature falls heat is released. Obviously the amount of heat exchanged is related to the mass of the "phase-change" material in the product.

A little breeze on a hot day is most welcome, since it will cool us by accelerating the evaporation of moisture from the surface of the skin. However, under cold conditions wind causes discomfort and a windproof outer garment is valuable, even essential under severe conditions. Fabrics having a high resistance to air penetration have been developed; they are closely woven to produce very small pores which increase air resistance. Vapour permeable coated fabrics now provide wind resistance and vapour permeability for high performance garments. The importance of maintaining loft (bulkiness) is important for windproof fabrics as well as thermally insulating fabrics. It has been found that the force of the wind can compress underlying fabrics or waddings, forcing out the air trapped in the clothing assembly.