Circular economy is increasingly promoted as a solution to decouple economic growth and environmental impacts. To design a circular and sustainable system, a structured approach is needed. In this study, we suggest to follow a 3-step approach. First, the status quo is evaluated using environmental assessment methods. We determine current circularity (share of assessed product and material retained and further used in the system), environmental impacts, the most impactful products and processes, and assess contaminants and impurities.