Since 1993, Japanese retailer Uniqlo has been driving innovation with its unparalleled approach to "solving the cold weather problem." Here we delve into exactly how HEATTECH® has become an indispensable pillar in Scandinavian fashion over the past two decades.

In the long history of centuries of people and clothing, the solution to fighting the cold has always been-rather simply-to make garments thicker and heavier. While the last few decades have brought a myriad of advances such as wind-resistant nylons and feather-filled technical clothing, winter clothing has remained an experience of being wrapped in bulky layers. That was until Uniqlo revolutionized the concept of staying warm with the introduction of HEATTECH® in 2003.

The brand had already been (figuratively) growing since the launch of its first store in Hiroshima in June 1984, becoming popular for its fleece and denim offerings, among other essentials. However, it wasn't until the late 1990s that Uniqlo began partnering with Toray, a Tokyo-based chemical company that is now nearly 100 years old-forming what would be a very productive and influential partnership in the fashion world.

"We seek to use the power of chemistry and chemical engineering to change the world for the better," explains Yukiko Teshigawara, general manager of Toray's environmental solutions department, speaking at Uniqlo's central office in the Ariake district of the Japanese capital. "By creating new value through innovative ideas, technologies and products. Materials have the power to transform society, to change lives. This concept is at the heart of everything we do."

"This collaboration has been an industry breakthrough," adds Yukiko Onishi of Toray's global operations department, describing HEATTECH® as a "key fruit" produced through the partnership between Uniqlo and Toray. In line with Uniqlo's philosophy of high-quality, affordable everyday clothing, a new innovation related to thermal underwear has emerged.

Together, the two forces created a new material from scratch. Teams from both sides came together with various ideas and strategies-and although these were some of the brightest minds in the apparel industry, the path was not without difficulties. Progress was slow and the road was peppered with repeated frustrations, but both Uniqlo and Toray remained inspired by their mission to create something that did not previously exist. "Even when we thought it was good enough, it still wasn't," says another Toray representative. Eventually, the efforts paid off: HEATTECH® was born, a thin, comfortable layer to keep people warm, transforming the way people live during cold seasons, all at an affordable price.

Delving into the unique features of HEATTECH®, Onishi boils them down to two key characteristics. "The first is that it absorbs moisture and generates heat," Onishi explains. "Our bodies produce water vapor without us realizing it, and the rayon inside HEATTECH® fabric absorbs that vapor. When that happens, the moisture molecules try to move, converting that kinetic energy into heat energy. The material traps the heat generated in pockets of air and retains it."

This is all highly technical, a fact that representatives of both Uniqlo and Toray do not deny. In Onishi's own words, the teams have "worked tirelessly" to make HEATTECH® what it is today-with improvements made every year, never compromising comfort. Much of the development comes from a dedicated weather simulation chamber at Uniqlo's Tokyo headquarters office-a large laboratory equipped to replicate various weather and humidity conditions, including negative temperatures that would make anyone in Scandinavia feel comfortable. The technology in the simulation chamber allows the Uniqlo team to accurately map areas of heat, perspiration, and movement on the bodies-sometimes of ambassadors or professional athletes.

Since 2003, the range has expanded significantly. From what began as a simple men's turtleneck, called Dry, HEATTECH® now includes T-shirts, crewneck sweaters, jeans, pants, vests, and more, for women, men, and children. The HEATTECH® line has also tripled in size with the introduction of HEATTECH® Extra Warm and HEATTECH® Ultra Warm, which are respectively 1.5 to 2.25 times warmer than regular HEATTECH®. Not to mention the prestigious collaborations HEATTECH® has undertaken along the way, the latest being with Japanese womenswear designer Mame Kurogouchi and French lingerie label Princess Tam Tam.

As HEATTECH®'s product categories have grown, functionality and overall comfort have seen a sharp increase in its popularity and general perception in the fashion world, including Scandinavians. A survey of fashion industry professionals during the Paris Fashion Week fall/winter '23 season found that more than half (51.2%) confirmed wearing HEATTECH®, with participants praising "warmth without bulk" as their favorite feature, followed by convenience and comfort.

So as the autumn chill sets in in the Nordic countries and queues form in front of Uniqlo stores in Scandinavia, rest assured that Uniqlo's HEATTECH® not only has the support of popular opinion, but also two decades of groundbreaking research and pioneering innovation behind it. And this is a trend that is set to continue. "Uniqlo and Toray will continue to progress over the years," Onishi confirms, "continuing to collaborate to create HEATTECH® garments that offer comfort to customers. You can expect the evolution to continue.