A new model of sustainable product development process for making trade-offs

The decisions made during product development (PD) lock in 70–80 % of total product cost, and the quality of the product is also largely fixed. Therefore, these decisions have a great influence on product life cycle cost, quality, and sustainability. To improve such decisions, designers need to make high-level trade-offs among various criteria to see their effects. Therefore, developing a model to support trade-offs for sustainable product development is a significant concern for designers. This research attempts to consider sustainability, quality, and cost simultaneously to make trade-offs between environmental issues and other customer requirements to select the best design specifications on their basis. Sustainability is considered as a customer requirement, which then is translated into design specifications. In this study, sustainable design is treated as an optimization problem to maximize value-added activities while minimizing environmental effects. Multi-attribute utility theory is utilized in order to formulate combination of the customer’s opinions and make a trade-off between different groups of customer requirements in the final model. An optimization model is then defined to model sustainability, quality, and cost in the product development process in order to find the optimum level of their combination thereof. By using this model, designers need not select between different solutions since they can find the optimal solution. A case study is illustrated and the results are discussed.