Summer is here and with it the heat waves common in the months of July and August. The solution, for most people, is to dress cool, avoid excessive exposure to the sun and use air conditioning. The latter is the most effective way to achieve a thermal sensation less burdensome, but requires high energy consumption. Scientists at the University of Chicago have developed an alternative solution that could be much more effective and less expensive: a new type of fabric capable of reducing the temperature, compared to the silk commonly used in shirts, dresses and other summer clothing, by 8.9 degrees and that responds to the name of SSHFinitials in English for spectrally selective hierarchical tissue.
Chenxi Sui and Ronghui Wu They are the researchers of the Pritzker School of Molecular Engineering from the University of Chicago, who have published an article in the journal Science with the advances achieved with this material. They emphasize that the problem of heat does not only come from the sun, but from cities that become in urban heat islands due to the multiplying effect of thermal radiation emitted by pavements and buildingsWith projections that by 2050, 68% of the population will live in cities, the scale of the problem is evident.
‘People usually focus on the performance or material design of cooling textiles. To make a textile that has the potential to be applied to real life, you must consider the environment‘, Wu explains in an article published by the University of Chicago.
According to his calculations, only 3% of the clothes a person wears directly face sunlight. The other 97% is heated by thermal radiation that reaches it from below and from the sides.against which solutions such as broadband emitting fabrics They cannot fight. These are the ones known as cooling fabrics that already exist for outdoor sports and that They work by reflecting sunlight in a diffuse pattern..
‘Sunlight is visible light, thermal radiation is infrared, so They have different wavelengths. That means you need to have a material that has two optical properties at the same time. That’s very challenging to do. You need to play with materials science to design and tune the material to give you different resonances at different wavelengths‘, Sui notes.
In tests conducted under the Arizona sun, Sui and Wu’s new fabric proved to be 2.3 degrees cooler than broadband emitting fabric used for outdoor endurance sportsBut the substantial difference is with common clothing, the 8.9 degrees of difference mentioned, and that the fabric can have other uses besides clothing.
Researchers are now working on a thicker version of the SSHF that is protected by an invisible layer of polyethylene and could be used to Coating the sides of a building or the exterior of a car, thereby reducing the temperature inside without using energy-consuming means. It could also be used to manufacture bags and boxes in which to transport fresh food without it spoiling due to heat.
‘You can save a lot on cooling, electricity and energy costs because this It is a passive process‘, says Sui about this invention for which they already have a provisional patent.