Australian Housing Study Finds Scope to Increase Recycled Materials
An Australian housing study has examined how recycled materials can be measured, verified, and increased within a completed modular dwelling. Its findings highlight opportunities to reduce demand for virgin resources while showing why recycled-content claims require closer scrutiny before they inform purchasing decisions.
Homes NSW commissioned GECA, also known as Good Environmental Choice Australia, to undertake the Recycled Content Verification Study using a dwelling supplied by MOOV Modular. Rebuilt provided the embodied-carbon assessment and scenario modelling.
Rather than assessing a proposed design, the project investigated materials incorporated into an existing home. GECA reviewed more than 100 sources, mapped over 20 material categories and examined six priority material streams in detail. The work combined supply-chain analysis with Australian and international benchmarking.
Establishing a Measurable Baseline
The assessment established a verified dwelling-level recycled-content baseline of 20.1% by weight, with verification covering 94.15% of mapped dwelling weight. This coverage matters because a headline percentage alone does not explain how comprehensively a building’s materials have been assessed.
The six priority streams were structural steel, aluminium, plasterboard, engineered wood, insulation and composite decking. Their different starting points demonstrate why a single recycled-content target would be difficult to apply meaningfully across all building products.
Aluminium and plasterboard showed substantial room for improvement compared with international practice. Insulation and composite decking were already closer to leading performance. The study therefore recommends setting requirements for individual materials and strengthening them progressively as supply chains and verification capabilities develop.
Material Opportunities Vary Significantly
Rebuilt’s account of the project provides further detail on those differences. Aluminium had no recycled content reported in the assessed baseline, compared with an identified near-term opportunity of 20–30%. This is a reporting result for the products assessed, rather than evidence that all aluminium used in modular housing contains no recycled material.
Plasterboard had reported recycled content of 4–7%, against an international benchmark of 20–30%. Engineered wood was reported at around 40%, compared with international opportunities of 70–90%.
By contrast, insulation had reported recycled content of 82%, close to the cited benchmark of 85–90%. Composite decking stood at 85%, with higher-performing alternatives offering further potential.
These figures suggest that procurement teams should distinguish between materials requiring substantial changes in sourcing and those where maintaining performance and improving documentation may be the immediate priority.
Recycled Content and Carbon Need Separate Assessment
The dwelling’s carbon footprint was assessed at 382.3 kilograms of carbon dioxide equivalent per square metre for lifecycle stages A1–A3. These stages cover raw-material supply, transport to manufacturing and manufacturing itself.
The figure should therefore be understood as a material production assessment, rather than a complete account of construction, operation and end-of-life emissions.
Modelling indicated that higher recycled content across the six priority streams could reduce this footprint by up to around 10%. However, this was a scenario result, not a reduction already achieved.
Structural steel illustrates the distinction between circularity and carbon performance. The report identifies steel as the dwelling’s largest carbon contributor and finds that changing its production route offers greater carbon-reduction potential than increasing recycled content within conventional steelmaking alone.
Verification Changes the Meaning of a Claim
The study also examined whether supplier information could substantiate the percentages being reported. A figure may describe an individual product, an average across a production line or the output of an entire manufacturing site.
Those boundaries affect how confidently buyers can apply the information to a particular building. Environmental Product Declarations, supplier statements, certifications and production records provide different forms of evidence and cannot automatically be treated as equivalent proof of recycled content.
For procurement teams, the practical implication is to specify both the information required and the evidence needed to support it. Asking for a percentage without defining its scope can produce figures that appear comparable while measuring different things.
Government Purchasing Can Shape Supply Chains
The findings identify public procurement as an important mechanism for improving both material performance and disclosure. GECA recommends introducing recycled-content and carbon evidence requirements at tender stage, with expectations increasing over time.
Consistent purchasing requirements across agencies could give manufacturers a clearer basis for investing in recycled inputs and traceability systems. The assessment also found that a relatively small group of manufacturers supplied significant material categories, creating opportunities for focused engagement with major suppliers.
A Pilot With Clear Limits
The report contains 16 recommendations covering procurement, verification, material targets and circular design. These include designing for disassembly, improving adaptability and tracking verification confidence alongside recycled-content performance.
Its conclusions nevertheless relate to one assessed modular dwelling. The study boundary focuses on the modular building package and excludes site-specific works and other elements unless captured in the project documentation.
The report also states that material provenance evidence was insufficient to establish verified landfill-diversion outcomes. Recycled content should consequently not be presented as proof of a particular quantity of locally recovered waste.
For housing providers and manufacturers, the pilot offers a method for building a stronger evidence base. Applying it across additional homes and suppliers would help determine which improvements can be repeated at scale.
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