Integrating life cycle assessment and systemic circularity indicators for circular economy decision making: A case study of a conventional commercial building in Nigeria

Circular economy has been seen as a model of production and consumption that aims to mitigate environmental impact and enhance resource recovery, reuse, and recycling. However, decision-making on whether reducing environmental impact will enhance resource recovery and vice versa based on various scenarios is often complex. Thus, it is important to consider eco-efficient and eco-effective perspectives during circular economy decision-making. Using the Life Cycle Assessment (LCA) from cradle-to-cradle (C2C) with a Predictive Building Systemic Circularity Indicator (PBSCI), this study enhances circular economy decision-making by assessing circularity level and impact potential of a conventional commercial building in Nigeria. By modeling various scenarios, the circularity of the case building is sensitive to the average product utility of materials and the circularity plans along the CE building blocks. The PBSCI results indicated that the base scenario achieves 50.6% circularity of the building's mass, whereas scenarios one to six exhibit circularity levels of 70.3%, 90%, 0%, 0%, 77.4%, and 85.6% by mass, respectively. Also, the LCA results advocated that the impact potential of the building is sensitive to the various PBSCI scenarios, the impact assessment methods, and the chosen EoL allocation approach. The environmental impact varies across scenarios, with the base scenario leading to substantial global warming potential and ozone layer depletion. As a result, the study recommends Scenario 2, which exhibits the maximum circularity and the lowest environmental impact, as the most eco-efficient and eco-effective option for the case building. This paper presents a novel framework for improving CE decision-making from the production stage of a building. The findings could guide product designers on the various alternatives to attain systemic circularity in product systems design.