Greening the Green: An Investigation of Circular Economy in the Life-cycle of Building Thermal Insulation

A stable economy is defined as an economy that generates profit without having negative impacts on the natural capital to provide a better future of living for the next generations. Sustainable Development (SD) is defined as the economy which considers economic development by considering future generations’ essential living requirements. As a major result of the current dominant economic model, which is called ‘take, make and dispose’, the term Circular Economy (CE) emerged as an effectual alternative method to provide a healthy economic growth method and further protection against natural capital depletion. The literature has proven the CE’s positive effect on economic growth, business potential and the environment. In the context of CE, Agent-Based Modelling (ABM) has attracted many researchers and enterprises to enhance the profitability of complicated economic systems comprising different components. Each individual component interacts with other ones and is considered an agent. Each agent can be comprised of several variables. The ABM is largely employed in different industries and fields, such as the housing market, agriculture, information, marketing, manufacturing, and logistics. Based on the aim of this research; by utilising the ABM platform, a single agent-based model was designed for product circularity assessment and Life-cycle Cost Analysis (LCCA) via AnyLogic simulation software. The model was developed, applied, and evaluated on a polyurethane (PUR) based polyisocyanurate (PIR) building thermal insulation product. Sensitivity analysis was successfully conducted to identify and assess the sources of uncertainty within the model. Moreover, the simulation results were compared against available secondary and experimental data. The research findings discuss how the proposed model applies to the circularity assessment of other similar supply chains. The results highlighted various cost-effective areas throughout the entire life-cycle of the chosen product. This thesis categorises the product's life-cycle into primary life-cycle and multiple after-life cycles as re-utilisation, repair, recycling, and landfill. The results of this study offer invaluable insights regarding material selection and its economic implications on the product's life-cycle cost. The study highlighted that there is a direct relationship between the raw material selection and the cost of energy consumption during the manufacturing process of the PIR building thermal insulation. Moreover, it was highlighted that transportation has a significant potential to increase costs directly linked to the distance between site deliveries and reversed logistics procedures. The results from this developed model identified that the contribution of the additional materials in the polyol recovery process of glycolysis recycling, along with the excessive methylene diphenyl diisocyanate (MDI), has a substantial effect on the cost of recycling of the PIR building thermal insulation. Also, the results identified that the cost of glycolysis agents and the catalyst contributed to 62% of the cost of the polyol recovery process compared to PIR waste. The developed model illustrated a substantial capability in conducting circularity assessment and LCCA and is applicable to any other products with minor modifications.