Development and application of an enhanced building circularity indicator: A pilot study in Taiwan

Abstract

The concept of circular economy, which promotes the reuse and regeneration of materials or products, is a key solution to the environmental challenges posed by the building industry. How this concept can facilitate the building sector's transition to sustainability has become a critical question for stakeholders. The Ellen MacArthur Foundation's “Material Circularity Indicator” (MCI) has been adopted to evaluate building circularity, but its application lacks comprehensiveness. This paper reviews existing literature on MCI for buildings and proposes an enhanced framework, the “Enhanced Building Circularity Indicator (EBCI),” to address these limitations. The EBCI incorporates often overlooked factors such as lightweight design, recycling levels, modularity, and a whole lifecycle perspective. The framework is tested through Taiwan's Taisugar Circular Village (TCV), the country's first circular housing project, which integrates circular economy strategies, including circular materials, modular design, and Product-as-a-Service business models. Results show that the EBCI effectively assesses building circularity across material, product, system, and building levels, highlighting the importance of recycling levels, modularity, and lifespan extension in improving circularity. The study also discovers that different normalization factors (mass vs. economic value) significantly impact the results. Including renovation times (RTs) in the assessment leads to minimal differences in circularity scores, suggesting limited additional value for this factor. The EBCI provides a comprehensive and adaptable approach to assessing building circularity, offering valuable insights for policymakers and industry stakeholders seeking to promote sustainable building practices.