Research Proposal – Circular Economy Practices in Australian Construction and Demolition Waste

Introduction and Background

Construction and demolition (C&D) waste is the largest single material stream in the Australian economy. National reporting places C&D generation at approximately 29 million tonnes per annum, close to 40 per cent of all waste generated, with a headline recovery rate of roughly 76 per cent (Department of Climate Change, Energy, the Environment and Water 2022). That figure is dominated by the crushing of concrete, brick and asphalt into low-value road base. Material accounts show the economic value recovered per tonne remains far below the value embodied in the original product (Australian Bureau of Statistics 2022), so most reported recovery is in fact downcycling rather than the retention of function.

Policy settings have tightened. The National Waste Policy Action Plan commits Australian governments to an 80 per cent average recovery rate by 2030, a 10 per cent per capita reduction in waste, and increased recycled-content procurement (Commonwealth of Australia 2019). Landfill levies now range from roughly A$80 to A$170 per tonne by jurisdiction and category, with strategies linking levy revenue to market development for recovered materials (NSW Environment Protection Authority 2021). Voluntary rating tools add parallel pressure: Green Star Buildings credits diversion, material transparency and reduced embodied carbon (Green Building Council of Australia 2021), and the Infrastructure Sustainability scheme scores resource efficiency on civil projects (Infrastructure Sustainability Council 2021).

Circular economy (CE) thinking offers a more ambitious response than incremental recycling. Rather than treating waste as an end-of-pipe problem, CE seeks to retain materials, components and assemblies at their highest utility through cycles of reuse, repair, remanufacture and, only as a last resort, recycling (Kirchherr, Reike & Hekkert 2017). Applied to the built environment, this reframes buildings as material banks and shifts attention upstream to the design, procurement and contractual decisions that determine whether recovery is possible decades later (Pomponi & Moncaster 2017).

Problem Statement

Despite favourable policy signals, the adoption of genuinely circular practices by Australian contractors and design consultants appears uneven and shallow. Diversion reporting is widespread because rating-tool compliance requires it, yet design for disassembly, structural reuse and high recycled content in load-bearing applications remain rare outside demonstration projects. The literature offers plausible explanations, including cost, standards uncertainty and weak client demand, but most evidence is European, drawn from different levy structures, denser secondary-material markets and different procurement law (Adams et al. 2017; Ghisellini, Ripa & Ulgiati 2018). No Australian study has tested which barriers actually predict adoption once firm size, project type and procurement mode are controlled, so policy risks targeting the most frequently mentioned barrier rather than the most binding one.

Aim and Research Questions

The aim of this research is to explain the adoption of circular economy practices in Australian construction and demolition activity by identifying the relative influence of barriers and enablers on contractor and designer behaviour, and by tracing how those influences manifest in the material flows of actual projects. Three research questions follow.

1. Which barriers to circular economy practice are most strongly associated with low adoption among Australian contractors and design consultants, and does that association vary by firm size, project type and procurement mode?
2. How do practitioners describe the mechanisms through which enablers such as landfill levies, rating-tool credits, recycled-content procurement requirements and Australian material standards translate into project decisions?
3. What do project-level material flows reveal about the gap between reported diversion performance and the retention of material value in Australian construction projects?

Literature Review

Circular economy principles in the built environment

Kirchherr, Reike and Hekkert (2017), analysing 114 definitions, showed that the CE concept is frequently reduced to recycling, with reuse and reduction receiving markedly less attention, which matters for construction because recycling captures the least value in the material hierarchy. Pomponi and Moncaster (2017) proposed a multidimensional research framework for the built environment, arguing that technical solutions fail when the behavioural and economic dimensions are ignored. Ghisellini, Ripa and Ulgiati (2018) concluded that selective deconstruction generally outperforms mechanical demolition environmentally, but that its economic case depends heavily on disposal costs, labour rates and the proximity of reprocessing infrastructure, and that conditionality is precisely why an Australian assessment is required.

Design for disassembly and material recovery

Design for disassembly (DfD) treats reversibility as a design objective, favouring mechanical fixings over adhesives, layering assemblies so short-life and long-life components can be separated, and documenting material composition so future recovery is informed rather than exploratory. Hossain et al. (2020) positioned DfD, together with digital material inventories, as the principal technical enabler of circularity, while noting that its benefits accrue to a future owner rather than the party bearing the initial cost. This temporal misalignment is a structural obstacle that market signals alone are unlikely to resolve.

Barriers to adoption

Adams et al. (2017) surveyed the construction supply chain and found high conceptual awareness coupled with low implementation, with cost, a lack of client interest and unclear standards cited most often. Two Australian features deserve particular attention. First, the acceptability of recycled aggregate in structural concrete is governed by AS 2758.1, and practitioner uncertainty about compliance pathways is reported as a deterrent to specification (Standards Australia 2014). Second, thin and geographically dispersed secondary-material markets raise transport costs, which on a continent of long haulage distances can neutralise the avoided-disposal saving that a levy is intended to create.

Procurement and rating-tool levers

Rating tools function as a demand-side lever, converting circular performance into a certifiable asset attribute. Green Star Buildings rewards documented diversion, responsible product certification and upfront carbon reduction (Green Building Council of Australia 2021), and the Infrastructure Sustainability scheme applies analogous credits to civil works, where recovered aggregates and reclaimed asphalt pavement are already routine (Infrastructure Sustainability Council 2021). Public procurement is a second lever, since recycled-content commitments under the National Waste Policy Action Plan aggregate otherwise fragmented demand (Commonwealth of Australia 2019). Whether these levers change contractor behaviour, or merely change contractor reporting, remains poorly evidenced.

Three gaps therefore emerge. The literature is dominated by European and Chinese settings; it seldom tests barriers as predictors rather than as ranked perceptions; and it rarely triangulates practitioner accounts against project material flows. This proposal addresses all three within a single Australian design.

Conceptual Framework

The study adopts a barriers and enablers model in which institutional and market drivers act on firm-level adoption of circular practices, which in turn produces diversion and embodied-carbon outcomes. Enablers and barriers are modelled as opposing forces on the adoption node rather than as a single continuum, since a firm may face strong levy pressure and a binding standards constraint at once. Figure 1 illustrates the framework and the feedback pathway by which verified project performance returns to influence the driver environment.

The framework is operationalised through the six domains in Table 1, each pairing a representative barrier with its counterpart enabler and the Australian instrument through which that enabler operates. Survey constructs, interview prompts and case-review coding categories are all derived from these domains, so the three phases interrogate the same structure from different angles.

Methodology

Research design

An explanatory sequential mixed-methods design will be used, in which a quantitative phase establishes the pattern of association and a subsequent qualitative phase explains it (Creswell & Plano Clark 2018). This ordering suits the problem because the relative weight of barriers is best resolved statistically, whereas the mechanisms linking enablers to decisions require practitioner accounts. A third component, project case reviews, provides material-flow evidence independent of self-report, guarding against the social desirability bias that affects sustainability surveys.

Phase 1: contractor and designer survey

An online questionnaire will be administered to a sampling frame of approximately 2,000 firms drawn from industry association membership lists covering builders, demolition contractors, architects and engineering consultants across New South Wales, Victoria, Queensland and Western Australia. A target of 250 usable responses represents a response rate of roughly 12.5 per cent, consistent with comparable Australian construction surveys, and provides adequate power to detect medium effect sizes across eight predictors at an alpha of 0.05. The instrument will measure adoption of eight circular practices on a behavioural frequency scale, perceived strength of the barriers and enablers in each of the six domains in Table 1 using seven-point Likert items, and firm characteristics including turnover, employee count, project type and procurement mode. Content validity will be established through expert review by four academics and four practitioners, followed by a pilot of twelve respondents excluded from the main analysis.

Phase 2: semi-structured interviews

Fifteen semi-structured interviews will be conducted with respondents purposively sampled from Phase 1 to maximise variation across adoption level, firm size and jurisdiction. Selecting participants on the basis of their survey responses is the defining feature of the explanatory sequential design and allows the protocol to probe deviant cases, such as small firms reporting high adoption despite severe cost barriers. Interviews of 45 to 60 minutes will explore how levy exposure is priced into tenders, how rating-tool credits are pursued or discounted, how standards uncertainty is resolved, and what would change the respondent’s behaviour on the next project.

Phase 3: project case reviews

Three completed projects, one commercial building, one civil infrastructure package and one residential development, will be reviewed to reconstruct material flows from waste dockets, subcontractor reports, specifications and rating-tool submissions. Two metrics will be calculated. The conventional diversion rate is recovered mass divided by total generated mass: for a project generating 2,400 tonnes of which 1,860 were recovered, diversion rate = 1,860 / 2,400 = 77.5 per cent. A value-retention ratio is the mass recovered at or above its original functional grade divided by total recovered mass: 340 / 1,860 = 18.3 per cent. The contrast between these figures operationalises the downcycling problem and provides the most direct answer to the third research question.

Analysis plan

Survey data will be screened for missingness and common method bias. Descriptive statistics will profile adoption levels; exploratory and then confirmatory factor analysis will test whether the six hypothesised domains are empirically distinct; and ordinal logistic regression will model adoption as a function of barrier scores, enabler scores and firm controls, reporting odds ratios with 95 per cent confidence intervals. Kruskal-Wallis tests will compare adoption across firm-size bands and procurement modes. Interview transcripts will be analysed thematically using a codebook derived from Table 1 and expanded inductively, with a second coder independently coding 20 per cent of the material and agreement assessed by Cohen’s kappa. Integration will occur through a joint display arraying statistical findings against the themes and case-review metrics.

Ethical Considerations

Approval will be sought from the university Human Research Ethics Committee before any recruitment, and the study will be conducted in accordance with the National Statement on Ethical Conduct in Human Research (National Health and Medical Research Council 2023). Participation is voluntary and informed by a plain-language statement, with consent recorded electronically for the survey and in writing before each interview. Commercial sensitivity is the principal risk, since waste performance and tender pricing are competitively significant. Firms and projects will therefore be de-identified in all outputs, described only by size band, sector and jurisdiction; case-review documents will be held on encrypted university storage and reported only in aggregated form; and participating organisations may review project descriptions before publication. Data will be retained for five years and then destroyed.

Project Timeline

The research is scheduled over 15 months, as set out in Table 2. The sequential design imposes a strict dependency between Phase 1 analysis and interview sampling, so the survey field period carries a contingency and the case reviews are deliberately overlapped with interviewing to protect the critical path.

Significance for Policy and Industry

For policy, the study offers evidence on which lever moves behaviour. If standards uncertainty predicts non-adoption more strongly than cost, further levy escalation will be an inefficient instrument, and effort is better directed at specification guidance and compliance pathways under AS 2758.1. If client demand dominates, the case strengthens for embedding circular requirements in public procurement rather than relying on voluntary rating tools. The value-retention metric also gives regulators a way to distinguish genuine circularity from high-volume downcycling, addressing a known weakness in headline recovery reporting (Australian Bureau of Statistics 2022).

For industry, the case reviews will produce a transferable method for reconstructing project material flows from documents contractors already generate, lowering the cost of internal benchmarking, while the interviews will articulate how higher-adopting firms resolved cost and risk problems that others describe as prohibitive. Academically, the study extends the built-environment CE research framework (Pomponi & Moncaster 2017) by testing its economic, governmental and organisational dimensions simultaneously in a jurisdiction with unusually long haulage distances and a mature levy system.

Limitations and Delimitations

Several limitations are acknowledged. The survey captures self-reported behaviour, which is vulnerable to social desirability; the case reviews mitigate but do not eliminate this. The sampling frame, drawn from association membership, will under-represent small and unincorporated operators, who may face the most acute capability barriers. Three case projects are intended to be analytically rather than statistically generalisable. The design is also cross-sectional, so associations between barriers and adoption cannot establish causal direction, and a firm’s adoption record may equally shape how severely it now perceives a barrier. By delimitation, the study addresses building and civil construction in four states, excludes resource-sector demolition and hazardous streams such as asbestos, which are governed by separate regimes, and does not attempt full life-cycle assessment of recovered materials.

Conclusion

Australia recovers a large share of its construction and demolition waste by mass while retaining comparatively little of its value, and the policy architecture now in place, spanning the National Waste Policy Action Plan, state landfill levies, rating tools and recycled-content procurement, has not yet produced widespread circular practice. This proposal sets out a 15-month explanatory sequential study combining a survey of 250 contractors and designers, 15 interviews and three project case reviews, structured by a barriers and enablers framework, to determine which constraints actually bind and how the available levers work in practice. The intended contribution is an evidence base specific to Australian conditions that allows regulators, clients and firms to direct effort towards the constraints that matter most.

References

Adams, KT, Osmani, M, Thorpe, T & Thornback, J 2017, ‘Circular economy in construction: current awareness, challenges and enablers’, Proceedings of the Institution of Civil Engineers: Waste and Resource Management, vol. 170, no. 1, pp. 15-24.

Australian Bureau of Statistics 2022, Waste account, Australia, experimental estimates, ABS, Canberra.

Commonwealth of Australia 2019, National waste policy action plan 2019, Department of the Environment and Energy, Canberra.

Creswell, JW & Plano Clark, VL 2018, Designing and conducting mixed methods research, 3rd edn, SAGE Publications, Thousand Oaks.

Department of Climate Change, Energy, the Environment and Water 2022, National waste report 2022, DCCEEW, Canberra.

Ghisellini, P, Ripa, M & Ulgiati, S 2018, ‘Exploring environmental and economic costs and benefits of a circular economy approach to the construction and demolition sector: a literature review’, Journal of Cleaner Production, vol. 178, pp. 618-643.

Green Building Council of Australia 2021, Green Star Buildings submission guidelines, GBCA, Sydney.

Hossain, MU, Ng, ST, Antwi-Afari, P & Amor, B 2020, ‘Circular economy and the construction industry: existing trends, challenges and prospective framework for sustainable construction’, Renewable and Sustainable Energy Reviews, vol. 130, pp. 1-16.

Infrastructure Sustainability Council 2021, IS rating scheme technical manual, version 2.1, ISC, Sydney.

Kirchherr, J, Reike, D & Hekkert, M 2017, ‘Conceptualizing the circular economy: an analysis of 114 definitions’, Resources, Conservation and Recycling, vol. 127, pp. 221-232.

National Health and Medical Research Council 2023, National statement on ethical conduct in human research, NHMRC, Canberra.

NSW Environment Protection Authority 2021, NSW waste and sustainable materials strategy 2041, NSW EPA, Sydney.

Pomponi, F & Moncaster, A 2017, ‘Circular economy for the built environment: a research framework’, Journal of Cleaner Production, vol. 143, pp. 710-718.

Standards Australia 2014, AS 2758.1-2014: aggregates and rock for engineering purposes, part 1: concrete aggregates, Standards Australia, Sydney.