A Systems Perspective on Mass Balance Accounting

In a new paper published by Rice University’s Baker Institute for Public Policy, Recycling Science Council Co-Chair Rachel A. Meidl, LP.D., CHMM, examines the ongoing debate over mass balance accounting and recycled-content attribution through a broader systems perspective. 

Mass balance is an accounting approach used to track certified materials through complex manufacturing systems and supply chains. Meidl explores how these accounting frameworks interact with broader circular economy goals, including material recovery, infrastructure investment, manufacturing and supply chain resilience. 

Her analysis centers on three principles: systems thinking, proportionality, and technology neutrality. The paper considers how accounting can provide credible, transparent, and independently verifiable information while examining the implications of increasingly detailed attribution requirements for markets, investment, and technology deployment.

Meidl also looked at the role of third-party certification and independent verification in supporting credible recycled-content claims and maintaining confidence in the accounting system.

As part of this broader framework, the paper asks policymakers to consider three questions when evaluating advanced recycling: whether processes produce legitimate commercial products, whether associated material flows can be independently verified, and whether resulting sustainability claims are transparent, credible, and auditable.

Ultimately, the paper encourages readers to consider mass balance as one component of a larger materials system and to evaluate accounting approaches alongside technical, economic, and environmental factors that shape plastics circularity.  

Read Rachel Meidl’s full paper, Optimizing the Circular Economy Through Better Accounting, here.