next winter, a new material promises to keep you warm when standing in freezing rain but cool when running around. Gateway Technologies in Colorado, us , has developed Outlast, a lightweight fabric that can adapt to changes in both body and environmental temperatures. The fabric keeps the wearer warm when they are inactive but switches to provide cooling when the wearer moves about.

Textiles rely on air trapped between the fibres for thermal insulation. The volume of air and consequently the thermal insulation properties of a fabric depends upon its thickness and density