This thesis explores how European fashion designers work with sustainability and how the use of eco-design tools can help designers develop more sustainable design strategies.
The research is based on a review of design literature and an exploratory empirical study of fashion designer practices. The study is based on interviews. The results are analyzed through the prism of practice theory (Shove et al., 2012) and more specifically of the three elements - materials, skills, meaning- in the context of fashion design. 
 Sustainability is implemented in fashion design mainly through the choice of materials and the competences related to sustainability are acquired through experiments, media, encounters and examples from other companies. Designers have highlighted some of their difficulties, notably that of marrying creative freedom with the imperatives of sustainability in a context where there is a lack of time and transparency of information. Eco-design tools could be an answer to these difficulties. However, they are only rarely used in the daily practice of designers.

Based on these observations, a proposal for a new qualitative, universal design tool is formulated. It takes the form of a digital platform aiming to facilitate access to information by relying on the factors of collaboration and inspiration that are very present in the practice of fashion designers.