Date of Award

5-2025

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Edgar Stach, Dr.-Ing

Second Advisor

Kihong Ku, DDes

Third Advisor

Dario Trabucco, PhD

Abstract

Executive Summary

The transition towards circular economy in the design and construction industry represents a transformative opportunity to align economic growth with environmental sustainability. This dissertation delves deeply into how circular strategies can be implemented within the construction sector, examining their potential to mitigate resource depletion and waste generation, while fostering innovation and efficiency. By integrating theoretical frameworks with empirical research, the study provides a robust understanding of the challenges and opportunities associated with circular models and offers actionable insights for stakeholders navigating the shift from linear to circular economic practices.

The backdrop for this research lies in the unsustainable nature of the traditional linear economic model, which dominates the construction industry. The environmental implications of this model are profound, including resource depletion, habitat destruction, and increased greenhouse gas emissions. Recognizing these issues, there is an urgent need to transition towards a circular economy, which emphasizes the regeneration of resources, reduction of waste, and sustainable development. Within this context, circular models offer a pathway to operationalize circular economy principles, enabling the design and construction industry to evolve towards sustainability.

The central research question addressed in this dissertation is: How can circular models be effectively implemented in the design and construction industry to support sustainability transitions? To answer this, the study explores the theoretical foundations of circular economy, their practical applications, and the systemic changes required to embed these models within industry practices. The research also identifies the benefits of circular models, including reduced material costs, improved resource efficiency, and enhanced competitiveness, alongside the barriers that hinder their adoption, such as regulatory challenges, cost concerns, and resistance to change.

The concept of the circular economy underpins this research, offering a paradigm shift from the linear model to one that prioritizes the closing, slowing, and narrowing of resource loops. In the construction industry, this involves designing buildings and infrastructure to maximize material recovery, minimize waste, and extend the lifecycle of materials and components. For example, prefabricated modular systems enable components like walls and beams to be easily dismantled and reused in new projects, reducing demolition waste and conserving resources. Additionally, closed-loop supply chains, where materials are continuously recycled and reintegrated into production processes, exemplify the practical application of circular economy principles in construction.

The literature review highlights the evolution of circular economy principles and their relevance to the construction industry. The transition from a linear to a circular model requires a fundamental rethinking of design, production, and consumption patterns. Key principles of the circular economy, such as designing for disassembly, material recovery, and shared ownership, are particularly relevant to construction. For instance, reversible connections in building structures allow for easy disassembly and reuse of components, while leasing models for building materials ensure that resources are returned and repurposed at the end of their lifecycle.

Circular models play a pivotal role in operationalizing circular economy principles. Circular models prioritize strategies that narrow, slow, and close resource loops, enabling companies to reduce waste and optimize resource use. In the construction industry, these models manifest in various ways, including design-phase models that incorporate sustainable materials and modular construction techniques, construction phase models that emphasize waste reduction and on-site recycling, and supply-phase models that establish closed-loop material recovery systems. The dissertation identifies key benefits, such as cost savings through material efficiency, reduced environmental impact, and enhanced brand reputation. However, it also acknowledges challenges, including the high upfront costs of implementing circular practices, limited availability of secondary materials, and regulatory barriers.

Empirical research forms a cornerstone of this study, combining multiple case studies and survey-based analysis to provide a comprehensive understanding of CBM adoption in the construction industry. The case studies examine companies implementing circular economy, offering insights into their experiences, challenges, and successes. For example, a Danish construction firm developed a materials exchange platform that enables contractors to buy and sell excess materials, reducing both costs and waste. Similarly, a UK-based modular housing company adopted a circular leasing model, wherein building components are rented rather than sold, ensuring their reuse at the end of their lifecycle. These examples illustrate the practical application of circular models and their potential to drive innovation and sustainability in construction.

Survey data complements the case studies, capturing the perspectives of nearly 150 construction industry stakeholders across Europe. The findings reveal common perceptions about circular models, with small firms citing upfront costs and lack of technical expertise as significant barriers, while large firms highlight challenges in integrating CBMs into complex supply chains. The survey also identifies key enablers of circular model adoption, such as government incentives, stakeholder collaboration, and capacity-building initiatives.

Regulatory and legal frameworks play a critical role in shaping the adoption of circularity in the construction industry. The dissertation examines the impact of policies such as the European Union’s Circular Economy Action Plan, which sets ambitious recycling targets for construction and demolition waste. While these policies create a supportive environment for CBMs, inconsistencies in local building codes and regulations often hinder their implementation. For example, stringent safety requirements for reclaimed materials, such as recycled concrete aggregates, limit their application despite evidence of their safety and performance. The research underscores the need for harmonized regulations that balance innovation with safety and quality standards.

A significant contribution of this dissertation is the development of a circular framework tailored to the initial design & planning phase of construction industry. This framework integrates design thinking principles with practical tools to guide stakeholders in implementing circular strategies. Key components include material flow mapping, which visualizes the lifecycle of materials to identify opportunities for reuse and recycling; a circular economy toolkit, featuring templates like the circular model canvas and collaboration strategies that foster partnerships between designers, contractors, and waste management firms. For instance, a construction firm in the Netherlands applied the framework to reclaim wooden beams from demolished buildings, treating and repurposing them for new flooring projects.

The findings of this research highlight the importance of experimentation and collaboration in overcoming barriers to circular model adoption. Internal experimentation, such as testing prefabricated wall systems made from recycled gypsum, demonstrates the viability of circular practices, while collaborative innovation, such as closed-loop concrete recycling programs, exemplifies the power of partnerships in driving sustainability. The research also emphasizes the adaptability of circular models, noting that strategies must be tailored to a company’s size, resources, and specific needs.

The dissertation concludes that circular economy offers a transformative opportunity for the construction industry to align environmental goals with economic benefits. However, realizing this potential requires a multi-faceted approach that includes policy support, industry collaboration, and capacity building. Policymakers must establish clear and consistent regulations that promote material reuse and innovation, while industry stakeholders must foster stronger partnerships to share knowledge and resources. Additionally, training programs are essential to equip professionals with the skills needed to implement circular models effectively.

Future research is recommended to explore the long-term impacts of circular models, including market integration and full-scale implementation. Emerging technologies, such as AI-driven material recovery systems and 3D printing with recycled materials, also warrant further investigation. By providing a comprehensive roadmap for integrating circular economy principles into construction, this dissertation offers practical tools and strategies to support sustainability transitions in one of the world’s most resource-intensive industries.

Comments

Presented in partial fulfillment of the PhD in Architecture & Design Research degree at Thomas Jefferson University.

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