Many industrial facilities can inventory Scope 1 (field fuel) and Scope 2 (purchased electricity) with OSOS and invoices; but 60–90% of the total carbon footprint is hidden in Scope 3—in materials purchased, logistics, use of product sold, and supplier energy consumption. In 2026, EU buyers, Turkish suppliers within the scope of TSRS and the CBAM chain; It is gradually rejecting the “spend-based” approach. Verifiable, activity-based data is becoming the new compliance standard.
60–90%
Scope 3 share (manufacturing)
Varies by industry
15
GHG categories
Upstream + downstream
Cat. 1–4
Priority (industry)
Purchasing + logistics
primary data
2026 expectation
Spend-based → activity-based
Why is Scope 3 a “blind spot”?
Scope 1–2 is within the factory limit; Your measurement infrastructure (meter, OSOS, fuel recording) is under your direct control. Scope 3, on the other hand, is fed by sources far from your field, such as the supplier's energy intensity, the origin of the raw material, the transportation mode and how the customer uses the product. Even if an automotive or machinery supplier reduces emissions by 20% at its own factory, it can only show its share of the buyer's Scope 3 inventory with primary data or a verified supplier declaration.
15 category summary
| Cat. | Category | Turkish industrial priority |
|---|---|---|
| 1 | Purchased goods and services | High — raw materials, external processing |
| 2 | capital goods | Medium — in the machinery/investment period |
| 3 | Fuel and energy (non-Scope 1–2) | Medium — transmission losses, WTT |
| 4 | Upstream transport and distribution | High — import/logistics |
| 5 | operational waste | Medium — disposal method |
| 6 | business travel | low–medium |
| 7 | Employee transportation | low–medium |
| 8 | Upstream leased assets | Depends on the industry |
| 9 | Downstream transport | Medium—distribution |
| 10 | Processing of the product sold | High — intermediate supply |
| 11 | Use of the product sold | High — energy consuming products |
| 12 | End of life of the product sold | medium |
| 13 | Downstream leased assets | low |
| 14 | franchise | low |
| 15 | Investments | financial sector |
Spend-based vs activity-based calculation
| Method | Formula / logic | Plus | Minus |
|---|---|---|---|
| Spend-based | Expenditure (₺/€) × EEIO emission factor | Fast, ERP data is enough | Poor control; price fluctuation distortion |
| average-data | Quantity × industry average (kg, kWh, ton-km) | Unit based; better than spend | It may not reflect the supplier's reality |
| Supplier-specific | Supplier primary data / LCA / EPD | Strong in buyer control | Survey load, data quality variable |
| Hybrid | Primary on significant items, remaining average | Practical transition model | Methodology should be documented |
The GHG Protocol data quality hierarchy positions primary supplier data at the top. Typical roadmap for Turkish manufacturer: (1) Cat. Choose 1 and 4, (2) start with spend-based inventory, (3) collect activity-based data from top 20 suppliers, (4) write into an annual improvement plan.
Supplier survey template — sample fields
ESG surveys submitted by buyers are becoming increasingly technical. The following areas are common in 2026 supplier evaluations; It can be used as a minimum template that you can send to your own suppliers.
- Reporting period and limit (operational control / financial control)
- Scope 1–2 total tCO₂e and verification level (self-declared / third-party)
- Annual electricity consumption (kWh) and renewable share (Is there YEK-G amortization?)
- Natural gas / fuel consumption (TEP or kWh equivalent)
- Specific emissions by product (kg CO₂e / kg product or / piece)
- ISO 14064, ISO 50001 or CDP participation status
- CBAM embedded emissions (product HS code + tCO₂e/tonne, if applicable)
- Reduction target and base year
- Data source: OSOS, meter, invoice — has it been reconciled?
CBAM, CSRD and TSRS printing
For suppliers of cement, iron and steel, aluminium, fertilizer and hydrogen within the scope of CBAM, embedded emissions must be reported with primary data — the financial and reporting schedule is detailed in our Carbon Tax, CBAM and Turkey guide. In the EU, CSRD/ESRS mandates Scope 3 for large buyers; In Turkey, TSRS 2 climate statements use the same data language. The threshold and calendar are up to date in our TSRS Sustainability Reporting guide.
Our guide to Carbon Neutral, Net Zero and Scope 1–2–3 gives the basis for Scope concepts; This article focuses on supply chain operation. The three regulations convey the same message: supplier emissions are no longer “the buyer's problem.”
2026: moving from prediction to verifiable data
- Spend-based inventory → identify items covering 80% emissions with materiality matrix
- Activity-based survey + Request OSOS/invoice proof to top suppliers
- Cat. Prioritize if product has LCA or EPD for 1
- Save tonne-km, mode and fuel type for logistics (Cat. 4)
- Align TSRS/CBAM reporting period and supplier data period
- Document the methodology change in the base year and recovery account
ENOPTIMAL: consumption data supplier declaration support
The “annual kWh, OSOS reconciliation, reagent/profile consistency” fields requested in the supplier survey are the same data format that you produce with ENOPTIMAL in your own factory. Keeping your own Scope 1–2 inventory strong will ensure that your representation to the buyer is credible; The same platform collects consumption, invoice and production data in a single source. You can reference the OSOS + submeter standard as a "measurement maturity" checklist in the supplier development program.
Conclusion
Scope 3 is no longer a "we'll do it in the future" category; In 2026, export, TSRS and major buyer contracts require activity-based data. First, materiality in 15 categories, then Cat. Collect supplier primary data in steps 1 and 4. With a demo request, we can evaluate your factory Scope 1–2 inventory and supplier survey data model together.