A decision-making framework for environmentally sustainable product design

Design is a process through which customer needs are transformed into product or service specifications, and then used to develop a model or prototype. The prototype is tested, and modifications are brought to it before the production process starts. Moreover, the design process may be divided into different stages, starting from the definition of the customer needs, going through the conceptual design phase and ending up with the detailed design. In this article, we address the conceptual design phase, where the customer needs are assumed to be known. The proposed approach considers, based on customer needs, primary and secondary design criteria. Each design criterion has a set of predetermined possible values (options) from which the designer may select. Making the best selection of all the design features while satisfying the customer needs in terms of cost, quality (customer preference) and environmental performance is a combinatorial problem and therefore a decision-making framework would be helpful for the designers. In this article, the design criteria are evaluated using fuzzy technique for order preference by similarities to ideal solution based on cost, quality and environmental sustainability. A multiobjective and a single-objective binary programming models are then developed and solved, and their optimal solutions are obtained. The multiobjective solutions provide the decision makers with the possible trade-offs, whereas the single-objective model solution can be used as a final decision-making tool. The proposed approach is implemented in a user-friendly software developed by the authors. A case study is conducted using a baby car seat for which three main and six secondary design criteria are considered. The obtained results show the effectiveness of the approach used.