Belgian researchers have revealed the concept for a fabric that can keep a person warm when worn one way and cool them down when worn the other way. Until now, most cooling fabrics have been made up of impermeable membranes that trap air and moisture against the skin, making them uncomfortable to wear. The team used the enhanced capabilities of photonic tailored textiles to solve this problem. They integrated infrared-emitting and absorbing components into mechanically flexible fabrics.

The Janus cloth with a thickness of 20 meters is named after the two-faced Roman god Janus. The material’s two interlaced sides are made up of two different types of fibers: dielectric and metallic, with highly differing infrared-emitting capabilities. On the one hand, dielectric fibers can release a considerable amount of radiation, but metallic fibers have a low emissivity. Janus textile is thin and flexible, in addition to its passive heating and cooling qualities. Moisture travels away from the body through gaps between the threads, assuring the wearer of comfort. For the time being, though, high manufacturing costs may prevent such reversible materials from appearing in clothing anytime soon. Large-scale production of the material is not currently practical but the findings can spur more study into comparable materials.