FREE SUSTAINABLE SUPPLY CHAINS LEARNING PATH

WikiFree original practice workbook

The circular exchange

CASE STATUS: fictional/synthetic teaching material. Do not present the example as real research, employment experience or measured business performance.

OUTCOME
Compare a new-product and repair route with a transparent footprint worksheet and a supplier evidence request.

BEFORE YOU START
Basic percentages and a spreadsheet or paper calculator. No environmental accounting software is required.

CASE
The fictional Cedar Repair Cooperative is considering repairing returned lamps instead of replacing them. The figures below are invented teaching assumptions, not verified emissions factors or a product environmental claim.

INPUTS
Route,Manufacture or repair kg CO2e,Transport kg CO2e,Useful service units
New lamp,8,1,100
Repaired lamp,3,2,80


ENTRY CHECK

Question: Why use a common service unit?

Self-check: Different useful lives make per-item totals misleading.

Question: Can a guessed factor support an audited claim?

Self-check: No. Record it as an assumption and seek evidence.

Question: Does recycling remove transport impacts?

Self-check: No. The collection and processing boundary still matters.

STAGE 1: Draw the return loop

Prerequisite: Basic percentages and a spreadsheet or paper calculator. No environmental accounting software is required.

Instruction: A return flow needs collection, inspection, routing and an owner for exceptions. Keep usable products distinct from parts recovery and disposal. A circular-looking diagram is not evidence of a smaller footprint. First identify what actually moves, which condition changes its route, and what information travels with it. A lamp that fails an electrical safety inspection must not silently enter the reuse route.

Practice task: Draw the five steps from customer return to the next user. Add separate routes for repairable and non-repairable lamps and label two unknowns.

Deliverable: A return-flow map with decision points.

Acceptance check: Every returned item has a disposition, an owner and an inspection checkpoint.

If stuck: If everything goes straight to reuse, add the inspection and rejection branch.

Record your work, decisions and evidence:




Record your result against the acceptance check:



STAGE 2: Set a fair comparison

Prerequisite: Bring your previous output: A return-flow map with decision points.

Instruction: State the functional unit before adding impacts. Our example compares one unit of useful lighting service, not one lamp purchase. Include manufacture or repair and transport for both routes; other effects are explicitly outside this simplified exercise. Dividing each route total by its service units permits a like-for-like comparison, but only within these assumptions. Avoid presenting this worksheet as a full life-cycle assessment.

Practice task: Write the functional unit and boundary. Calculate total kg CO2e per lamp and per service unit for both routes.

Deliverable: A boundary statement and normalized comparison.

Acceptance check: New is 9/100=0.09; repaired is 5/80=0.0625 kg CO2e per service unit.

If stuck: If you compare 9 and 5 alone, normalize by the unequal useful service.

Record your work, decisions and evidence:




Record your result against the acceptance check:



STAGE 3: Test an assumption

Prerequisite: Bring your previous output: A boundary statement and normalized comparison.

Instruction: A result can depend more on an uncertain input than on arithmetic. Change one assumption at a time and preserve the baseline. At 40 service units, repair rises to 0.125 kg CO2e per unit and loses its advantage. The break-even repaired service life is 5/0.09, about 55.6 units. This is sensitivity analysis, not proof of actual product performance.

Practice task: Test repair lifetimes of 40, 60 and 80 service units. Explain what evidence would resolve the choice.

Deliverable: A sensitivity table and a decision threshold.

Acceptance check: All three scenarios use the same 5 kg total and disclose that service life is assumed.

If stuck: Do not change lifetime and transport together unless you label a separate combined scenario.

Record your work, decisions and evidence:




Record your result against the acceptance check:



STAGE 4: Ask suppliers for evidence

Prerequisite: Bring your previous output: A sensitivity table and a decision threshold.

Instruction: An evidence request should identify the measurement period, unit, method, boundary and responsible person. A supplier sustainability slogan cannot populate a calculation cell. Track whether each value is measured, estimated or missing. Involving repair staff also reveals practical constraints such as parts availability and inspection time that a carbon-only comparison misses.

Practice task: Draft five questions for a repair supplier and a simple evidence register. Include one question about safety inspection and one about service life.

Deliverable: A supplier evidence request with owners.

Acceptance check: Every numeric assumption has a requested source or a visibly unresolved status.

If stuck: Replace vague requests for green credentials with the specific data your calculation needs.

Record your work, decisions and evidence:




Record your result against the acceptance check:



STAGE 5: Write a bounded recommendation

Prerequisite: Bring your previous output: A supplier evidence request with owners.

Instruction: A recommendation combines the comparison, uncertainty and operating conditions. Prefer a controlled pilot when critical evidence is missing. Name the conditions that would stop the pilot, the person who reviews returns and the data required to revisit the estimate. Do not describe a smaller modeled footprint as certified, carbon neutral or legally compliant.

Practice task: Write a one-page pilot recommendation with a measurement plan, inspection gate and review date.

Deliverable: A conditional circular-supply pilot brief.

Acceptance check: The brief states the simplified boundary, threshold, unresolved evidence and stop condition.

If stuck: Remove absolute environmental claims that go beyond the worksheet.

Record your work, decisions and evidence:




Record your result against the acceptance check:



WORKED CASE
The modeled repair route is 0.0625 kg CO2e per service unit versus 0.09 for new. Its modeled reduction is about 30.6%, but a 40-unit repaired life reverses the choice. A defensible brief therefore recommends checking useful life and transport evidence before making any public claim.

FINAL PROJECT
Deliver the return map, normalized comparison, sensitivity table, supplier request and a conditional pilot decision. Add a new transport assumption of 4 kg CO2e for repaired lamps and explain whether the 80-unit route still improves on new.

REQUIRED CRITICAL CHECK
All comparisons use the same functional unit and clearly label invented factors.

SCORING
Score each of the five stage acceptance checks from 0–16 (0 missing/incorrect; 8 partially supported; 16 complete and evidenced). Score the final integrated project from 0–20 (0 missing; 10 incomplete handover; 20 complete, reproducible and consistent with the case). Target: at least 80/100 AND the critical check must pass. A total score never overrides a failed critical check.

SCOPE LIMIT
This small educational comparison is not a verified life-cycle assessment, legal review or product certification.

SOURCES AND ACCESS
Assigned public videos can be watched free. Complete the original case in a text editor, on paper or in a spreadsheet you already have. No paid course, exam or provider certificate is included.

Free MIT Course: Sustainable Supply Chain Management
WikiFree: https://wikifree.com/courses/mit-sustainable-supply-chain-management/
Official source: https://www.youtube.com/playlist?list=PLUl4u3cNGP632pcFMkw9J-JWmasU6rFcn
Why selected: MIT lectures supply reverse logistics, footprint boundaries, stakeholder engagement and strategy; the lamp worksheet is original WikiFree practice.

Stage 1 selected lessons:

1. Lecture 3: Reverse Logistics and Closing the Loop (1:01:01)
https://www.youtube.com/watch?v=e_Hpp8cgeRs&list=PLUl4u3cNGP632pcFMkw9J-JWmasU6rFcn&index=1

Stage 2 selected lessons:

3. Lecture 5: Life Cycle Analysis (1:23:22)
https://www.youtube.com/watch?v=gpuvUU0Nl4k&list=PLUl4u3cNGP632pcFMkw9J-JWmasU6rFcn&index=3

Stage 3 selected lessons:

2. Lecture 4: Carbon Footprinting (1:12:42)
https://www.youtube.com/watch?v=OgpNXj2cEzA&list=PLUl4u3cNGP632pcFMkw9J-JWmasU6rFcn&index=2

Stage 4 selected lessons:

4. Lecture 7: Multi-stakeholder Engagements (1:02:26)
https://www.youtube.com/watch?v=UBfckR8Ne5c&list=PLUl4u3cNGP632pcFMkw9J-JWmasU6rFcn&index=4

Stage 5 selected lessons:

6. Lecture 10: Green Supply Chain Strategy (1:22:27)
https://www.youtube.com/watch?v=A0owfH3UERI&list=PLUl4u3cNGP632pcFMkw9J-JWmasU6rFcn&index=6

REUSE
Original WikiFree teaching text and synthetic fixtures are supplied for personal learning and adaptation with attribution. Provider lessons remain on their original sites and retain their own terms. No provider certificate is included.