Thermal comfort is a vital requisite for work productivity or even survival in extreme weather. However, energy experts have predicted that by the middle of this century, global air-conditioning power consumption will reach 12% or more of total electricity demand. The energy consumption of air conditioning in buildings has become an urgent problem that needs to be optimized and solved.
Dr. Po-Chun Hsu, an assistant professor in the Department of Mechanical Engineering and Materials Science at Duke University, has proposed a “radiative personal thermal management” system by providing an innovative solution to achieve personalized thermal comfort in an energy- and health-oriented manner. By engineering the nanostructure of textiles and mid-infrared nanophotonic properties, he developed waterproof wearable fabrics that can provide extra heating or cooling to the users without any extra energy input, thereby saving building heating/cooling energy and providing a healthy thermal environment.
Thermal radiation, just like colors, is a surface phenomenon, which only needs a few tens of microns to obtain the heating/cooling properties, unlike the traditional textiles that need millimeters or even centimeters thickness. Regarding radiative personal thermal management, Po-Chun Hsu further explained that this is a way to achieve heating or cooling effects by adjusting the amount of radiant heat emitted. The concept is similar to smart clothes which aim to regulate the “valve” of human body heat loss rather than actively provide extra thermal energy to supply/remove heat from the human body, so it is much more efficient than the electric heater/cooler.
However, there is still a long way to go before actually realizing and manufacturing these clothes. Po-Chun Hsu has a more in-depth plan for radiative personal thermal management. He is expecting that people can use radiant heat management with very little energy consumption in the future to achieve a personalized setting of a somatosensory comfortable temperature. Compared to the current temperature control equipment driven by electric energy, the way to adjust radiant heat is more like a "valve" for adjusting the intensity of heat dissipation, rather than actively providing heat, which only takes a small amount of energy to keep most of the heat around.
In the future, he also hopes to realize the intelligent control of wearable materials through this solution.
"Just like we can now use mobile phones to control lights and microwave ovens. One day we can use mobile phones to control our clothes to adjust its functions."