Scenario-Based Assessment of End-of-Life Reuse and Recycling Strategies for Steel and Concrete in Residential and Commercial Buildings: Impacts on CO₂ Emissions and Energy Use

Abstract

The construction and demolition sector are a significant contributor to global CO₂ emissions and energy consumption, largely due to the widespread use of carbon-intensive materials such as steel and concrete. With the ongoing rise in global building demand, managing CDW through circular EOL strategies, particularly reuse and recycling has become increasingly critical to advancing sustainability and climate objectives. This study assesses the long-term environmental impacts of four EOL strategies for steel and concrete in residential and commercial buildings across 26 global regions between 2005 and 2060. EOL Material Flow Modeling is employed to simulate how much material recovery in this process , while associated CO₂ emissions and energy consumption are estimated using region-specific data from the IMAGE model (SSP2 scenario), Four scenarios are developed to reflect varying levels of circularity: (1) Business-as-Usual, (2) Enhanced Reuse, (3) Enhanced Recycling, and (4) a Combined Strategy that integrates improvements in both reuse and recycling. Scenario outcomes are evaluated based on key environmental indicators, including total CO₂ emissions, energy use, and material efficiency per unit of emission and energy. The results indicate that the Scenario 4 achieves the most substantial reductions in emissions and energy demand across all regions, particularly in high-growth areas such as China, India, and the United States. . The Scenario 2 also demonstrates strong performance, especially in contexts with developed reuse infrastructure and enabling policies. Scenario 3 offers moderate benefits, while Scenario 1results in limited environmental improvement. Significant regional variation is observed, reflecting differences in production technologies, building lifespans, and the effectiveness of material recovery systems. The findings highlight the critical role of integrated reuse and recycling strategies in promoting circular construction practices and reducing the environmental footprint of the building sector. They also emphasize the need for regionally tailored approaches based on local material flow dynamics, technological readiness, and policy support. By quantifying the environmental benefits of alternative EOL strategies, this research offers evidence-based insights for policymakers, industry stakeholders, and urban planners aiming to transition toward more sustainable and resource-efficient construction systems.