Clothes with built-in air conditioning? How is the demand for wearable cooling technology growing exponentially, and how are startups doing it?

In the United States, work is underway to commercialize wearable technology that mimics air conditioning, while scientists in China are working on a highly reflective fabric. With more heat and heatwaves expected in the coming years, cooling has become the holy grail for clothing makers.

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“As climate change pushes temperatures in extreme directions, consumer demand for cooling clothing is also growing at a faster pace,” says Sophie Bakalar, partner at Collaborative Fund, which invests in green apparel startups.

“This trend is likely to continue as industrialization in the Global South increases and consumers have more disposable income to spend on convenience.”

Productivity is also affected. In 2021, heat exposure cost 470 million hours of work globally in agriculture, construction, manufacturing and the service industry, according to data compiled by The Lancet, a medical journal.

Research shows that heat waves are likely to become more frequent in the coming decades. For companies like Technic, this is a recipe for growth.

Today, the startup sells jackets, hats, neckbands and other apparel with built-in cooling technology to businesses and individual customers in nearly 30 countries.

In 2022, it generated revenues of around £7 million (US$8.8 million), compared to £150,000 in 2014, when Technique launched refrigerated baseball caps as its first commercial product.

“The market is growing tremendously,” says co-founder and managing director James Russell.

The company is now developing a cooling vest that will be equipped with smart sensors capable of monitoring workers’ biometrics and predicting when they might be at risk of heat exhaustion.

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It is also working on equipment that can absorb heat using phase change materials, which NASA originally developed to help astronauts maintain a constant body temperature in space.

Just as traditional air conditioning units keep a space cool by transferring heat outside, Chen has made palm-sized thermoelectric devices that react to the preferred temperature set by the user.

The devices are powered by rechargeable lithium-ion batteries, which are small and flexible enough to be integrated into clothing. They provide the maximum reduction in skin temperature by 10°C.

Chen says his research team has already partnered with a California-based startup to commercialize the technology. They still need to develop an automated production line that can manufacture thermal devices on a large scale, which would cut production costs from several thousand dollars per T-shirt to nearly $200 (HK$1,500).

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Scientists manipulated polyester’s structure using nanomaterials and a redesigned weaving technique, resulting in a material that reflects nearly 90% of the sun’s rays, according to a 2021 study published in the journal Science. A traditional white cotton T-shirt reflects about 60% of the sunlight.

Reflective polyester also emits more infrared energy than regular fabrics, lowering body temperature.

According to the study, the material can remain up to five degrees Celsius cooler than ambient air temperatures in the middle of the day, and as much as 10 degrees Celsius at night. While their work has not yet been commercialized, the study authors say that polyester is “readily compatible” with the apparel industry.

Hot summers have fueled innovation across a range of consumer products and wearables. Tokyo-based company Kochofuku has developed a fan-equipped baby carrier, while another Japanese company, A-Mec, is making a cooling vest for dogs.

Even with a variety of approaches, most of these cooling solutions face similar limitations, says Bacalar of the Collaborative Fund.

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The biggest of these factors is price, which must come down to make high-tech refrigeration equipment affordable and attractive. Even at a production cost of US$200 per shirt, Chen’s air-conditioned clothing would be too expensive for most people.

Techniche’s cooling suit costs about the same as the average suit worn by construction workers in the US and Europe, says Russell, but costs more than four times as much as comparable workwear in the developing world.

Some cooling clothing comes with other trade-offs. To work for eight hours, Chen’s air-conditioned clothing is combined with approximately 1.5 kg (3.3 lb) of electronic components. Techniche’s cooling jacket is 20 percent heavier than the traditional option. Then there are the limited styles offered, and the constant skepticism of potential buyers.

“It is worth noting that there are no rigorous firewalls required to validate brand claims about cooling yet,” Bacalar says.

All of these drawbacks are part of what makes outdoor workers such a good demographic to target: Cool clothes are more of a necessity for them than a novelty, and companies that hire such workers tend to foot the bill.

Russell says that nearly 90 percent of Technich’s revenues come from sectors such as construction and oil exploration.

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“There will come a time when people will need to wear cooling clothing with sensors, just to walk on the street,” he says. “It’s not tomorrow. It’s not the day after. (But) it’s absolutely inevitable.”