Mass-balance / Material Flow
Material inputs, outputs and stocks for a system boundary over a period, balanced by mass.
Bundle → Layer → Finding → Questions Filled
3 bundles · 3 layers · 6 findings · 13 questions
System definition What is balanced, within which boundary and for which period.
Boundary and period
The system boundary, its processes and the accounting period.
System boundary
The processes, site or territory included in the balance.
- Which processes, sites or territory lie inside the boundary?
- Which flows cross the boundary, and which are internal?
Accounting period
The period over which flows and stock changes are balanced.
- Which period does the balance cover?
- Are opening and closing stocks stated for that period?
Flows and stocks The quantities that enter, leave and accumulate.
Flow accounts
Inputs, outputs, losses and stock changes for each material.
Material flows
Each input and output flow with its material, quantity and unit.
- Which materials enter and leave the system, and in what quantities?
- Are quantities stated on a dry or wet basis, and in which unit?
- Which losses, such as emissions or waste, are counted as outputs?
Balance closure
Whether inputs equal outputs plus stock change within stated uncertainty.
- Does the balance close, and how large is the unexplained difference?
- How was the uncertainty of each flow estimated?
Claims and allocation How balanced quantities support claims about content.
Chain-of-custody allocation
Allocation of certified or recycled input to outputs under a declared model.
Allocation model
The chain-of-custody model used, such as mass balance, segregation or book and claim.
- Which chain-of-custody model is declared for this balance?
- Which allocation rule assigns certified input to specific outputs?
Credit account
The ledger of certified input credits and their use over time.
- How many credits were received and claimed in the period?
- Has any credit been claimed twice or carried beyond its allowed period?
Classifiers Filled
- Family
- World Models
- Category
- Physical world and living systems
- Entry kind
- standalone-mm
- Navigation path
- NAV.PHY.FLW.MAT
- Domain
- PHY.FLW.MAT
- Industry
- Cross-industry
- Tags
- massbalancematerialflowphy.flw.mat
What it is Filled
A mass balance is an accounting of material flows into, out of and stored within a defined system boundary over a period, following the principle that mass is conserved. It covers material flow analysis of processes, sites, sectors or economies, and chain-of-custody models that balance certified and uncertified inputs; single shipments and stock positions are outside the class.
Why it exists Filled
Material inputs, outputs and stocks for a system boundary over a period, balanced by mass.
Distinguishing features Filled
- It balances flows and stock changes over a period within a boundary, not single shipments or movements.
- Conservation of mass is the test: inputs must equal outputs plus stock change within stated uncertainty.
- A chain-of-custody mass balance allocates certified content by accounting, not by physical tracing.
- Resource consumption records measure use of a resource; the mass balance accounts for where the material goes.
What robots and AI may and may not do Filled
Must not
- Adjust flows to force a balance to close without recording the adjustment.
- Present a mass balance allocation as proof of physical content in a specific product.
- Issue or transfer certified credits without the certification body's rules being met.
- Change the system boundary between periods without stating it.
- Hide losses such as emissions or waste from the balance.
Only with a human decision
- Signing off a balance used for a certification, regulatory or financial claim.
- Choosing or changing the chain-of-custody model.
- Writing off unexplained differences.
May
- Compile flows and stock changes for a defined boundary and period.
- Check whether the balance closes and report the difference with its uncertainty.
- Trace which inputs support a claimed share of certified or recycled content.
- Flag credits that appear to be claimed twice.
Moral aspects Filled
- Mass balance claims can mislead buyers about the real content of a product if not explained.
- Hidden losses shift environmental burdens onto communities near the site.
- Credible balances underpin circular economy and climate policies that affect many people.
Who is affected
- Buyers and consumers relying on content claims
- Communities near production sites
- Certification bodies and auditors
- Producers and recyclers
Owners Filled
Steward
The operator of the system boundary, such as a plant or company, accountable for its material accounts.
Master systems
- Enterprise resource planning material ledger
- Certification scheme credit registry
- National material flow accounts
Links to other meta-models Filled
references
- wm-flw-012-inventory-movement - Movements supply the flows that are balanced.
related
- wm-flw-013-supply-chain-trace-chain-of-custody - Mass balance is one chain-of-custody model.
neighbor
- world-f5-waste-and-circular-flows - Waste and recycled flows enter and leave the balance.
What else AI and robots need to interact with it Filled
Identity and identifiers required Filled
- A balance is identified by its system boundary, period and the issuer's reference.
- Materials are identified by product or material codes, such as Harmonized System codes for trade flows.
- Certified credits carry identifiers from the certification scheme's registry.
Direct properties required Filled
- Mass of each input, output and stock change in kilograms or tonnes, for the stated period.
- Moisture or dry matter content where flows are reported on a dry basis, as a percentage.
- Content of the tracked substance or certified share as a mass fraction.
- Uncertainty of each flow, stated with its estimation method.
Recognition optional Filled
- A balance states a boundary, a period, inputs, outputs and stock changes for named materials.
- Often confused with an inventory snapshot, a single shipment record or a product content label.
Capabilities and actions required Filled
- Flows can be aggregated by material, process and period.
- Balance closure can be tested and differences reported.
- Certified input can be allocated to outputs under a declared rule.
Hazards and failure modes required Filled
- Greenwashing through overstated recycled or certified content claims.
- Undetected losses of hazardous materials when balances are not closed.
- Double counting of credits across sites or periods.
Standards and interfaces required Filled
- Eurostat economy-wide material flow accounts for national reporting.
- ISO 22095 chain of custody terminology for mass balance models.
- Certification scheme credit registries for certified content claims.
Context of use required Filled
- Used in industrial ecology, process engineering, recycling and certification schemes.
- Regulatory reporting of emissions and waste often depends on site mass balances.
Sources Filled
- ISO 22095 Chain of custody - General terminology and models, ISO
- Economy-wide material flow accounts handbook, Eurostat
Open questions
- Planned model: boundary questions, research and every section remain to be written.
Machine files
Provenance
planned (registry candidate) · todo
Built from: models/runtime-index.json, ver-cy/world-models/card-supplements/wm-flw-008-mass-balance-material-flow.json
Planned entry, hidden from the catalogue until researched.