Development of circularity indicators based on the in-use occupation of materials

Abstract

Circularity can help to prevent depletion of the earth’s limited material resources, which are vital for human’s modern society. Circular economy strategies of slowing and closing loops of resources have the ultimate goal of keeping materials useful (i.e. in-use) while avoiding losses (dissipation) and hibernation of materials; therefore, appropriate indicators that can measure these aspects are necessary. We propose a measurement of the circularity of materials by quantifying their in-use occupation, that is, the maintenance of materials in a useful state in products for as long as possible, avoiding dissipation or hibernation. Specifically, two indicators were developed: in-use occupation ratio (UOR) and final retention in society (FRS). These indicators were applied in two case studies (materials in a laptop and wood products) with three scenarios each (linear, reuse, and recycling). The reuse scenarios generally presented a higher UOR (41–48% for laptop materials and 53% for wood) compared to recycling scenarios (29–45% for laptop materials and 52% for wood). Only two scenarios of wood products resulted in retaining materials for the next generation (FRS > 0%). We argue that the differentiation between supply, in-use, and hibernation phases is essential for a circular economy. The occupation of materials is shown in charts to facilitate understanding by non-experts and can provide a scientific basis for policies supporting technologies or products with increased in-use occupation and retention of materials.