A circular supply chain closes the loop: end-of-life material is collected and recycled back into manufacturing instead of becoming waste, reducing dependence on virgin extraction.
Circularity = recycled_input / total_input
Linear model: material → waste (single pass)
Circular model: material ⇌ recycle loop, leakage = 1 - recycling_rate
- Recycling rate — fraction of collected end-of-life material successfully routed back into manufacturing rather than landfilled.
- Production throughput — how fast new units are manufactured and enter the "use" phase.
- Virgin material need — minimum fraction of every batch that must come from newly extracted raw material (process/quality constraints), shown as gold particles entering the loop.
- Mode toggle — switches between a fully circular loop (recycle → manufacture) and a linear model (recycle station disabled, everything collected is landfilled) for direct comparison.
Real-world application: circular-economy strategies (e.g. EU Circular Economy Action Plan, closed-loop metal and plastics recycling) aim to raise circularity indices like this to cut raw-material extraction and landfill volumes.