Assessing the circularity and sustainability of circular carpets — a demonstration of circular life cycle sustainability assessment

Abstract

Abstract Purpose Robust assessments are needed to identify the best circular economy (CE) approaches related to their contribution to achieving a CE by simultaneously considering the complexity of the three pillars of sustainability (environmental, economic, social). In this regard, the circular life cycle sustainability assessment (C-LCSA) framework was recently developed. This study aimed to demonstrate its applicability and capability of identifying trade-offs and interlinkages between the different dimensions using a case study of different CE approaches to carpet tiles. Methods C-LCSA integrates circularity and life cycle sustainability assessments (LCSA). Thus, this study applied the material circularity indicator (MCI) in parallel to life cycle assessment (LCA), life cycle costing (LCC), and social life cycle assessment (S-LCA). The last technique was applied as social hotspot assessment. Five CE approaches of carpet tiles produced in the US, including strategies like reducing the consumption of primary materials through recycled and bio-based feedstock or replacing carpet tiles for a longer overall service life, as well as recycling, were assessed and compared to their mainly linear counterpart. Results and discussion The study revealed that recycling carpet tiles containing recycled and bio-based materials at the end-of-life (EoL) resulted in the lowest global warming potential (8.47 kg CO2 eq.) and the highest circularity (MCI value of 0.76, with 1 indicating the maximum level of circularity) compared to the other scenarios. However, this scenario had a trade-off with a higher acidification potential (0.039 kg SO2 eq.) and higher costs (US$19.98) compared to the disposal scenario. On the other hand, the scenario using primary, non-bio-based materials in production and disposing of the carpet tiles at their EoL performed the worst in circularity (MCI value of 0.11) and implied high environmental impacts while being more cost-effective (US$10.27). Conclusions C-LCSA transparently revealed interlinkages in terms of circularity and the overall sustainability performance of different CE approaches. While no significant differences in terms of social hotspots were identified, approaches associated with a higher circularity and improved environmental performance in most impact categories tended to result in higher costs. This emphasized the need for individual and holistic assessments of the new CE approach to identify and address trade-offs. To enhance and foster C-LCSA in academia and industry, further studies applying the framework to different sectors are encouraged.