1.3.1 Long term goal and project aim
This research investigates possible improvements to the management of existing building components; specifically, retaining or increasing the performance of components that are no longer needed to perform the duty in the building for which they were intended.
The envisaged route to change is development of academic knowledge of systems for building component reuse, repurposing and upcycling, such that, over time, this knowledge has the gravity and substance to influence policy and prompt innovations that are put into practice by industry actors, entrepreneurs, or university spin-out organisations.
To contribute to this long term goal, the project seeks to generate knowledge that sparks a new orientation towards valuing secondary materials. The aim of the project is to investigate, propose and test systems for reuse, repurposing and upcycling of existing building components.
1.3.2 Research scope, objectives and thesis structure
The research aim is undertaken through a predominantly qualitative mixed methods approach.
The project begins in the locale of the industrial sponsors (Poplar HARCA and Tower Hamlets Homes; Appendix A) and their operations in the London Borough of Tower Hamlets. It develops theory about urban systems that could enable reuse, repurposing and upcycling of existing building components, and then, based on this theory, examines a practical case of using secondary timber as feedstock for cross-laminated timber (CLT). CLT is a structural building component formed of layers of timber laminated at right angles to one another. It is manufactured offsite in panels up to 16 m in length, 4 m in width and 300 mm thick, for use as wall, floor and roof elements. Commercial production began in the 1990s, and volumes have grown exponentially as CLT’s market share has increased (Brandner, 2013).
The theoretical work at urban scale and the practical work at product scale are mutually supportive aspects of the thesis. The research objectives and sub-objectives in pursuit of the project aim are as follows.
Research objective 1: Describe what happens to building components at end-of-use;
explain why the construction industry relies on waste management; and propose how a system of component management would differ.
1.1 Observe and investigate waste logistics, monitoring, attitudes and behaviours on construction sites and at waste transfer stations;
1.2 Reflect on and describe the systemic mechanisms that appear to influence management of end-of-use building components;
1.3 Propose alternative means of managing end-of-use building components in response to these systemic mechanisms;
1.4 Plan the steps, responsibilities and actions that could enable a transition to component management.
Research objective 2: Investigate how information about ‘existing buildings as material banks’ is currently obtained; propose means of improving information flows to support component management; and test how this could facilitate the emergence of reuse, repurposing and upcycling ideas.
2.1 Critically review existing practices and research that can contribute to an understanding of E-BAMB;
2.2 Examine the limitations of these practices for supporting reuse, repurposing and upcycling;
2.3 Show how new approaches to generating E-BAMB knowledge can address present shortfalls;
2.4 Discuss these proposals in the light of other relevant advances to illustrate a scenario for future knowledge of E-BAMB.
Research objective 3: Investigate the environmental implications of using secondary timber as feedstock for CLT; test the fabrication process and mechanical properties of cross-laminated secondary timber (CLST); and discuss the practical feasibility and economic drivers of a CLST enterprise.
3.1 Review the existing context of waste wood removed from building stocks and the present use of CLT in new construction;
3.2 Make CLST and cross-laminated primary timber (CLPT) at small-scale and examine their compressive and bending stiffness and strength;
3.3 Examine the potential effects of manmade defects and reduced properties of individual lamellae on properties of CLST;
3.4 Make recommendations for further research necessary to advance this concept to pilot-scale and commercial application;
3.5 Model the enterprise system that would produce CLST and use it to test the credibility of theories developed in pursuit of research objectives 1 and 2.
Figure 3: Thesis structure.
Figure 3 sets out the structure of the thesis. Chapter 2 critically reviews existing literature and Chapter 3 explains the methodology adopted in this project. Together, the opening three chapters establish the need to develop better management of existing building components to improve upon the global environmental impacts of the construction industry. Chapters 4 and 5
bring this perspective to bear on urban systems of component management. Chapter 4 addresses research objective 1 and Chapter 5 addresses research objective 2. They aim to contribute to knowledge that can inform policymakers, as well as advancing the academic field through a new emphasis on repurposing and upcycling as alternatives to direct reuse. Chapter 6 addresses research objective 3. It exemplifies an approach to existing building components by examining the case of CLST as a potential upcycled product and the notional enterprise that would bring it about.
1.3.3 Publications arising from this research
1. Rose and Stegemann (2018a), From Waste Management to Component Management in the Construction Industry, published in the MDPI journal, Sustainability. The present author’s contribution to the paper was as primary author. The paper’s introduction and review is an abridged version of sections 1.1 and 1.2 of the thesis, and the remainder of the paper is included in Chapter 4 of the thesis. The article’s specific contributions include:
Critical review of existing literature and waste interventions that seek to mitigate construction industry environmental impacts and bring about reuse of building components;
Multiple case studies to examine systemic mechanisms that lead to components being discarded, such as the failure to identify components in advance;
Development of a triage process to address identified flaws and separate out those components that can be reused, repurposed or upcycled;
Identification of responsibilities for policymakers, clients, design teams, new upcycling enterprises and academia within the triage process, to increase capacity for component management and thus mitigate industry's environmental impacts.
2. Rose and Stegemann (2018b), Characterising Existing Buildings as Material Banks (E-BAMB) to Enable Component Reuse, published in the Proceedings of the Institution of Civil Engineers journal Engineering Sustainability. The present author’s contribution to the paper was as primary author. The paper is included in Chapter 5 of the thesis with minor amendments to remove duplication. The article’s specific contributions include:
Critical review of existing practices and research that can contribute to an understanding of E-BAMB;
Examination of the limitations of these practices for supporting reuse, repurposing and upcycling;
Description of new approaches to generating E-BAMB knowledge that may address present shortfalls;
Discussion of these proposals in the light of other relevant advances to illustrate how an E-BAMB information system could be formulated and strengthened in future.
3. Rose et al. (2018), Cross-Laminated Secondary Timber: Experimental Testing and Modelling the Effect of Defects and Reduced Feedstock Properties, under peer review at the MDPI journal, Sustainability. The present author is the paper’s primary author, leading the topic’s conceptualisation and rationale, coordinating investigations and others’ contributions, writing the majority of the paper and editing. The paper draws together work conducted under the supervision of the primary author by Master’s students, Evi Unubreme and Tianyao Lyu (experiments), and Thibault Dufresne (Finite Element Modelling; FEM), and includes Mechanically Jointed Beams Theory (MJBT) calculations that were designed, carried out and described by Dan Bergsagel of Scale Rule. Portions of the text that describe work that was undertaken primarily by a collaborator from a different discipline are reproduced in italics. The paper is included in Chapter 6 of the thesis with some additional sections that were removed in the submitted version. The article’s specific contributions include:
A carefully evidenced proposal for the use of secondary timber emerging from demolition to make CLST as an example of upcycling – an alternative to reuse (which is often impractical), or conventional waste management (which chips or incinerates wood and does not capitalise on the residual value and performance of solid timber);
Preliminary research to explore the practical feasibility of making CLST;
Preliminary investigation of the mechanical properties of CLST, using three complementary techniques:
• experimental testing of the stiffness and strength of CLST and a control in compression and bending,
• FEM of the potential effects of manmade defects on CLST stiffness in compression and bending, and
• MJBT calculation of the potential effects of reduced secondary timber stiffness due to ageing on CLST stiffness in compression and bending;
Identification of research questions for further work to advance the concept of CLST towards commercial application.
4. Romero et al. (2019), Quantification of Material Stocks in Existing Buildings Using Serendipitous Data: A Case Study on Timber in a London Borough, in preparation. The present author is the paper’s secondary author, conceiving the study, providing access to sources of data, supervising investigations by the primary author, writing elements of the paper and reviewing. The paper develops a method for understanding the components in existing building stock with sufficient detail to inform reuse, repurposing and upcycling. The method is applied to the case of timber in residential buildings in the London Borough of Tower Hamlets. An abstract of the paper is included in Appendix B.
Conference contribution 1. Rose et al. (2015a), Mining the construction process and our existing building stock: an assessment of current demolition and waste management practices and a triage process for resource valorisation, delivered by the present author at WASCON 2015 – Resource Efficiency in Construction in Santander, Spain. The paper assesses current construction and demolition waste management based on multiple case studies. It introduces the triage process and identifies areas of intervention. The extended abstract is included in Appendix C.
Conference contribution 2. Rose et al. (2015b), Viable and scalable reuse in construction: the case of upcycling waste wood to make cross-laminated timber, delivered by the present author at UCL Urban Sustainability and Resilience Research Showcase in London, UK. The presentation discussed current management of wood waste, put forward the principle of CLST and reported the results of initial mechanical testing. The abstract is included in Appendix D.
Conference contribution 3. Rose and Stegemann (2016), Triage: Designing a Materials Management Framework for secondary use of construction components, delivered by the present author at EU COST Action Mining the European Anthroposphere in Odense, Denmark.
The presentation discussed the triage process for separating out reusable components from materials to be sent to waste management, and reported on live case studies testing the triage in practice. The abstract is included in Appendix E.
Conference contribution 4. Rose and Stegemann (2017), An urban triage for existing construction components entering the waste stream, and the case of cross-laminated timber upcycled from waste wood, delivered by the present author at Positions on Circularity in the Built Environment in Munich, Germany. The presentation discussed the triage process and preliminary research to explore the feasibility and practicality of CLST, including pilot production by the author. The abstract is included in Appendix F.