With the increase of global production, the fashion industry and the textile industry must be transformed, which poses increasingly difficult challenges to sustainable, circular economy. Design starts with the selection of materials, so this thesis explores the roles of conventional and new types of yarn from the aspects of sustainability and effects on human health. The diversity of raw materials is highly important if we want to prevent the depletion of resources. For this, the use of new materials and new methods are essential – these must suit how the world now works and what society needs, and they must also be optimal for the product from a design perspective.