Design for longevity is known as an eco-design opportunity and could help to reduce the environmental footprint of energy-free items. However, extending the lifespan of products is not always desirable and the focus should be on achieving an optimal lifespan. Operationally, recommendations for design for longevity usually refer to durability, repairability, upgradability or emotional attachment. The use of high-quality and robust material is frequently stated, although it is not obvious what high-quality material is. Based on a quality by design approach, this study aims to propose a methodology to design for optimal longevity with a consumer-oriented approach. To do so, it includes data collection of product quality and manufacturing processes and then embeds consumers’ knowledge. These are combined into data analysis to help to highlight relationships and the most appropriate quality contributors. This methodology relies on three-steps: first, a single quality score which includes consumers’ knowledge; secondly, a multi-scale reverse-engineering process; and finally a data analysis using principal component analysis. The originality of such a proposal is that it enables the consumers’ knowledge to be considered in the identification of appropriated quality contributors. The proposed methodology is implemented in the fashion sector as it is said to be the second most polluting one. Moreover, given the huge variety of materials and production processes available in textiles, the selection of the most suitable recommendations to support a longer lifespan is very complex. The presented case study involves 29 T-shirts and reveals the mechanical-related strengths to be the main quality contributors.

In the clothing industry, the understanding of the quality is a major issue to well meet the customer needs. The dilemma that faces manufacturers is to find the balance between good quality and “overquality,” what the quality criteria are, and how to target requirements specifications. The aim of this study was to propose a multi-attribute ranking method of products. Ranking is based on an overall quality score. The quality score, here called consumer-based quality, is computed via the combination of textile testing and consumer perception to deterioration. Such a perception has been surveyed, and damage that can lead to end of life has been investigated. Collected data have been translated into a consumer sensitivity using multi-criteria decision making and fuzzy techniques. The fuzzy analytic hierarchy process has been used. Five damage categories have been weighted. A selection of appropriate tests according to standards has been completed to test the product resistance to the damage. The tests results have been computed with the consumer sensitivity to obtain the consumer-based quality score. Finally, the ranking method is applied on T-shirts, and a single score ranking is made possible and objectively depict perceived quality.

The use phase of clothing contributes significantly to the overall environmental impacts due to clothing care practices. Decreasing environmental impact while maintaining washing performance in the use phase can be an effective strategy for sustainability and circularity in the textile value chain. However, existing studies on the environmental impacts of use phase usually consider limited washing conditions and neglect their impacts on washing efficiency. This study proposes a research framework that integrates the Response Surface Methodology (RSM) and Life Cycle Assessment (LCA) methodology to optimize washing parameters for better washing efficiency with less environmental impact in the clothing use phase. A series of laundry experiments were conducted to simulate household laundry, and an environmental impact assessment was conducted based on the experimental data. The optimized washing parameters were explored under eight impact categories and in terms of washing efficiency, and comparative analyses were conducted between three different washing scenarios. The results indicated that input load is the most significant factor influencing both washing efficiency and environmental impact, but with a negative correlation. The optimized washing conditions provided effective trade-offs, demonstrating notable environmental benefits through the scenario study. In the daily washing scenario with an expectation for a middle level of washing efficiency, using the optimized washing conditions can reduce the environmental impact by 80% on average compared to the high-washing-efficiency-oriented washing process and 60% on average compared to the low-environmental-impact-oriented washing process. However, for high washing efficiency demand, optimized washing conditions are less competitive due to increased washing time and detergent use. The results emphasized the importance of choosing appropriate washing parameters according to the demand for washing efficiency. Consistent environmental improvements can be achieved by changing consumer washing habits.

The Ecole Nationale Supérieure des Arts et Industries Textiles (ENSAIT) is one of the few schools specialising in materials for the textile industry. Each year it graduates around 110 engineers whose role is to meet the challenges of the sector while respecting the values of the companies and environmental standards. The ENSAIT engineer's course takes place over three years. From the first year of the engineering cycle, a seminar on sustainable development is offered. It is held in the second semester and lasts two full days. The first objective is to make them aware of corporate social responsibility (CSR) issues in companies. The second is to build on the knowledge acquired during the last 6 months to develop the life cycle of a garment and understand the associated impacts. Finally, it is to highlight the different possible strategies based on eco-design, fair trade, taking into account the regulatory constraints. This seminar is based on active pedagogy, where students work in teams and compare their results with each other. It also aims to provide the minimum tools to understand ecodesign strategies and to be an informed fashion consumer, and to become a textile engineer capable of participating in and technically supporting companies' CSR initiatives.

Afin de répondre aux enjeux environnementaux actuels, l’économie circulaire ambitionne de découpler la croissance économique de la consommation de ressources. Pour y arriver, elle se base sur la volonté d’accroitre l’efficience de ces ressources en s’appuyant, entre autre, sur l’allongement de la durée de vie des produits. Seule réserve, la notion de durée de vie est à la fois liée au produit et au consommateur et pour cette raison, elle est particulièrement complexe à appréhender, à définir et à évaluer.Par ces travaux nous souhaitons donc contribuer aux réflexions qui portent sur la durée de vie et en particulier sur celle des produits textiles. Pour cela, nous avons construit des indicateurs comme aide à la décision, ils permettent de répondre aux problématiques suivantes : l’estimation de la durée de vie, l’identification des paramètres d’écoconception et l’évaluation du bénéfice de l’allongement de la durée de vie.Le modèle d’estimation de la durée de vie proposé, dénommé « Qualité Orientée Consommateur » (QOC), s’inspire de la définition de durée normative proposée par l’ADEME. Il s’appuie en effet sur des données objectives et retranscrit la capacité des produits à résister au vieillissement. Aussi, afin de faire concorder ce score avec la durée de vie, nous avons pris le consommateur en compte en s’intéressant notamment à sa perception vis-à-vis de l’usure.S’intégrant dans la démarche d’écoconception et d’économie circulaire, nous souhaitions nous servir de la connaissance du consommateur pour adapter la fabrication des produits. Nous avons donc associé le score QOC aux caractéristiques des produits dans une analyse de données afin d’identifier les paramètres influents, ainsi connus nous pouvons dégager des recommandations de fabrication.Enfin, nous avons mis ce modèle en œuvre au cas des T-shirts et avons vérifié l’adéquation du score QOC par rapport à une durée de vie « réelle », durée que nous avons intégrée dans des scénarios d’analyse du cycle de vie (ACV) afin de quantifier l’intérêt des produits de plus longues durées de vie. L’ACV offrant un angle statique, nous avons proposé de nouveaux points de vue plus dynamiques : en observant l’évolution des impacts dans le temps, nous sommes effectivement en mesure de quantifier l’influence de la durée de vie d’une part et d’évaluer la cohérence d’une chaine de fabrication par rapport à la qualité produite d’autre part.