The 7-Eleven products are famous for their use of the company’s patented technology of coffee charcoal fibers and a high percentage of Tencel fabric.
A series of similar products launched by lingerie maker Wacoal, priced between NT$980 and NT$1,300, have also outsold wool thermal undergarments by more than two times because of their relatively low prices, better warming effects and improved comfort level, said Wacoal lingerie adviser Liu Chiung-hui (劉瓊惠), who is based in the Shin Kong Mitsukoshi Department Store’s Xinyi Branch.
In light of the lucrative market for thermogenic clothing, OK Mart convenience stores also recently started selling similar products manufactured by the Far Eastern Group, whose warming effect is certified by the Swiss-based Societe Generale de Surveillance to be able to raise body temperature by 4.5°C after wearing them for six minutes.
Societe Generale de Surveillance, registered in Geneva in 1919, is a leading inspection, verification, testing and certification company.
However, customers are advised to pay close attention to the information labeled on such products, as certification criteria have not yet been established in Taiwan.
In China, only clothing that helps increase body temperature by 4°C or above, while managing to maintain a certain average temperature, can be labeled as thermogenic garments, Chiu said.
He added that Japan only certifies clothing that can raise body temperature by a certain number of degrees within a stipulated timeframe as qualified heat-generating clothes.
Chiu said Taiwan may adopt certification standards similar to those employed by China and Japan.
Taiwan Textile Federation secretary-general Justin Huang (黃偉基) said the nation could adopt certification criteria for the effects of heat-generating clothes by early next year.
While manufacturers of such products would not be ordered to send samples for testing and certification, those who pass the criteria are can apply for a certification mark to prove their products’ quality, Huang said.