This animal, more than any other, has become a symbol of man-made climate change. At the same time, however, it is a role model for technologies that protect the climate. Its fur is unique and serves as a model for solar thermal applications.
Nature inspires technology: This is a way of explaining bionics in simple terms – science that tries to solve technical problems using biological models. Biologists work closely with engineers, architects and materials researchers. They have already drawn inspiration from the polar bear on several occasions. The non-slip sole of its paws, for example, is used by developers as a model for the texture of winter tires, while the special texture of its fur has its counterpart in high-tech air-cushioned outdoor clothing.
Some climate protection technologies for buildings also imitate the tricks of the Arctic resident – especially its thermal insulation, which it owes to the solar thermal properties of its fur. Polar bears live in the most extreme weather conditions, can withstand even the lowest temperatures and can swim for hours in ice-cold water. This is made possible by its dense, yellowish-white coat, under which there is a black epidermis and a layer of fat to provide thermal insulation. Although the hairs shimmer a yellowish white, they are colourless. They direct a portion of the sunlight to the black epidermis – in doing so, solar radiation is converted into heat energy. Some experts talk about 'polar bear fur format solar collectors' in this context.
At the Institute of Textile Technology and Process Engineering in Denkendorf near Stuttgart (Germany), for example, researchers have been working with nature's Arctic model for many years – and have developed what is known as transparent thermal insulation. This is a textile-based heat-insulating material that is suitable for covering solar collectors, for example. The transparent, specially coated upper side relays the sunlight. A dark, absorbing layer on the underside aids heat production. The think tank also caused a sensation some time ago with its polar bear marquee – an energy self-sufficient, textile membrane structure that stood on the site until last year. In it, incident sunlight fell onto an airflow solar collector, which also served as an efficient energy heat exchanger. The lowest layer consisted of a black coated textile fabric, the absorber, which absorbed the energy. The follow-up project currently on the agenda is the integration of a long-term heat accumulator to be integrated into the textile membrane. Warm summer air thus reaches a long-term storage system with silica gel, in which it is "stored" until winter time. Another layer in the building envelope ensures high thermal insulation to the outside – responsible for keeping the winter cold away.
