Circular function deployment: a novel mathematical model to identify design factors for circular economy

The circular economy is applied in product design to address resource scarcity problems. Prior studies on circular economy associated with product design show a lag of interest in quantifying and assessing the product circularity score, which can support the product designer to identify the improvement opportunities. To address the gap, this study attempts to develop a circular function deployment method using 23 circularity metrics to compute product circularity score and identification of improvement opportunities. An empirical study by choosing a toothbrush as the case product is conducted to evaluate the effectiveness and practical applicability of the proposed method. The assessment of the current design shows that circularity metrics such as upgradability and adaptability, disassembly and reassembly, longevity, and biological cycle have to be addressed to improve the product circularity score. The design expert team’s knowledge has been utilized to develop a new design for toothbrush by addressing the critical metrics, which results in an incremental improvement to product circularity score for essential components from 0.583 to 1.136 without affecting the product functionality. The findings motivate the practitioners to explore the circular economy concepts in their product design to establish their market competitiveness.