When buildings are renovated or demolished across Europe and Asia, millions of tonnes of polystyrene insulation foam enter the waste stream every year. Expanded polystyrene (EPS) and extruded polystyrene (XPS) are among the most widely used thermal insulation materials in construction, valued for their exceptional strength-to-weight ratio, moisture resistance, and long-term thermal performance.
But there is a problem embedded in these materials — literally. For decades, construction-grade polystyrene foam was manufactured with hexabromocyclododecane (HBCD), a brominated flame retardant added to meet fire safety regulations. HBCD was the dominant flame retardant for EPS and XPS insulation worldwide, with typical concentrations of 0.7% in EPS and up to 2.5% in XPS.
In 2013, HBCD was listed under Annex A of the Stockholm Convention on Persistent Organic Pollutants, triggering a global phaseout. The substance was identified as persistent, bioaccumulative, and toxic — it resists environmental degradation, accumulates along food chains, and poses documented risks to aquatic organisms and human health. The EU classified HBCD as a Substance of Very High Concern under REACH and prohibited its use in new EPS production from 2015 (XPS) and 2017 (EPS).
The industry transitioned to a polymeric brominated flame retardant known as PolyFR, a styrene-butadiene copolymer with higher molecular weight and lower bioaccumulation potential. PolyFR is now standard in new construction-grade EPS and XPS. However, the legacy stock of HBCD-containing insulation in existing buildings is enormous — representing decades of installation — and is only now beginning to reach end of life as buildings undergo renovation or demolition.
Under the EU Persistent Organic Pollutants Regulation, waste containing HBCD above the unintentional trace contaminant threshold of 100 mg/kg must be managed to ensure the destruction of the POP substance. In practice, this has meant that most HBCD-contaminated EPS from construction demolition is sent to incineration or hazardous waste treatment — destroying a valuable polymer resource in the process.
Mechanical recycling cannot solve this problem. Grinding and re-melting HBCD-contaminated EPS simply carries the contaminant into the recycled product. Even conventional chemical recycling approaches face difficulties: depolymerising contaminated PS produces a crude styrene stream containing brominated compounds and closely boiling impurities that standard distillation cannot adequately separate.
The same challenge applies to PolyFR-containing insulation. While PolyFR is considered a safer alternative to HBCD, it still needs to be removed from the styrene stream to produce monomer of sufficient purity for re-use in sensitive applications.
Sulzer Chemtech’s EcoStyrene™ technology was developed specifically to handle the most challenging polystyrene waste streams — including construction-grade EPS and XPS contaminated with HBCD, PolyFR, and other legacy additives.
The process uses a combination of advanced depolymerisation, quenching, and proprietary extractive distillation to achieve what conventional separation cannot: the complete removal of flame retardant residues, brominated compounds, closely boiling species such as o-xylene and phenylacetylene, and other contaminants. The result is styrene monomer that meets ASTM-grade specifications — pure enough for food-contact packaging, medical devices, and other demanding applications.
This is a remarkable material transformation: polystyrene insulation foam that spent decades in a building wall, containing a banned persistent organic pollutant, is converted into monomer that can be safely re-polymerised into a food tray or yoghurt cup. No downcycling, no quality compromise, no contaminant carryover.
The wave of HBCD-containing insulation reaching end of life is accelerating as Europe’s building renovation wave gathers pace. EU energy efficiency directives are driving large-scale retrofitting of older building stock, generating significant volumes of legacy EPS demolition waste. At the same time, the PPWR mandates increasing recycled content in plastic packaging from 2030, creating demand for high-quality recycled styrene that can only be met through advanced chemical recycling.
EcoStyrene™ connects these two needs: it provides a safe, validated route for managing hazardous legacy insulation waste while simultaneously producing the food-grade recycled styrene that the packaging industry urgently requires. For waste managers, it transforms a disposal cost into a revenue-generating feedstock. For polymer producers and brand owners, it delivers a verified source of recycled content for regulatory compliance.
Every unit operation in the EcoStyrene™ process has been individually validated at commercial scale. The technology is offered as a licensed solution, enabling deployment in new plants or as an upgrade to existing recycling facilities. Sulzer’s engineering capabilities span the full project lifecycle, from initial feasibility studies through to plant commissioning and after-sales support.
The ability to accept flame-retardant-contaminated feedstocks is not a marginal feature — it is the defining advantage that unlocks the single largest untapped polystyrene waste stream in Europe and beyond. Construction and demolition PS waste has been waiting for a technology that can handle it safely and profitably. EcoStyrene™ delivers that solution.
To learn how EcoStyrene™ can support your operations, contact Sulzer Chemtech Process Solutions at solutions.sulzer.com