Sweat-wicking and radiative cooling: can new fabrics make living through extreme heat more bearable?
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Newer textiles aim to maximise heat transfer to the surrounding environment, a process known as radiative cooling. In 2018 Song and his colleagues engineered a fabric made from polyethylene, a common plastic, which they embedded with nanoparticles of zinc oxide, a compound used in sunscreen. In field tests using simulated skin, under full sun the fabric resulted in temperatures 5C to 13C cooler than cotton. “The new textile actually transmits about 90% of the body’s thermal radiation,” Song says. “It feels just like bare skin.”
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Common wisdom suggests that wearing white in summer will keep you cooler than black. That’s because black fabrics typically absorb more energy from the sun. “Black cotton fabrics typically absorb 80 to 90%, or even higher, of incoming solar radiation,” Song says. In comparison, white cotton fabrics absorb somewhere between 30% and 60%, he estimates. “So you will still feel hot under the sun even if you’re wearing white cotton.”
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A similar fabric his team developed can reduce skin temperature by 2.3C indoors, a difference they suggest corresponds to a 20% saving in the energy needed for air conditioning.
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Dr Shadi Houshyar, a senior lecturer at RMIT University, and her colleagues have developed a method of coating cotton with a thin layer of nanodiamonds, resulting in temperatures 2C to 3C cooler than regular cotton.
“It’s like a really thin layer of tissue [paper] on the surface of the fabric,” she says. “The fabric feels comfortable.”