Meaning
Chain of custody accounting rules within sustainability certification standards govern the mathematical allocation of recycled or bio-based feedstocks to specific finished polymer outputs. In chemical recycling and circular resin manufacturing, mass balance attribution tracks alternative inputs through co-processing facilities where physical separation of circular and fossil molecules is impossible. The method governs the issuance of certified sustainability claims on polymer datasheets and commercial resin invoices.
Accounting boundaries stop where material losses leave the physical system or when mass balance credits expire past their rolling eligibility window.
Allocation Model
Co-feeding pyrolysis oil alongside fossil naphtha in steam crackers blends circular carbon directly into the general olefin pool. Chemical plants calculate mass conservation balances across the cracker and downstream polymerization units to assign sustainability attributes to designated product batches. A plant converting ten percent recycled feedstock can attribute that total recycled volume to a high-value film grade resin while selling the remaining output as standard fossil grade.
Site audits verify that total attributed claims never exceed actual circular feedstock inputs.
Credit Transfer
Book and claim rules dictate how circular attributes transfer between site inventories and corporate entities under mass balance attribution guidelines. Certified credits remain valid until physical accounting periods expire.
Supply Auditing
Third-party certification bodies inspect mass balance accounting ledgers to prevent double counting of recycled feedstocks across supply chains. Molders receiving certified resin rely on precise attribution documentation to support environmental product declarations for consumer packaging.
