For most companies, the emissions that matter most are the ones they do not own. Scope 3 emissions — the indirect emissions across a company’s value chain — typically dwarf its direct (Scope 1) and energy (Scope 2) emissions, often accounting for the large majority of the total footprint. As IFRS S2, CBAM and ESG ratings increasingly demand value-chain data, Scope 3 has moved from optional to unavoidable for Thai companies. This guide explains what Scope 3 covers, why it matters, and how to approach it.
What Scope 3 Emissions Are
The GHG Protocol divides emissions into three scopes. Scope 1 is direct emissions from owned or controlled sources. Scope 2 is indirect emissions from purchased energy. Scope 3 is everything else — the indirect emissions across the value chain, both upstream (suppliers, purchased goods, logistics) and downstream (use and end-of-life of products). Because it spans the whole value chain, Scope 3 is usually the largest and the hardest to measure.
The 15 Scope 3 Categories
The GHG Protocol defines 15 Scope 3 categories, split into upstream and downstream:
- Upstream — purchased goods & services; capital goods; fuel- and energy-related activities; upstream transport & distribution; waste generated in operations; business travel; employee commuting; upstream leased assets.
- Downstream — downstream transport & distribution; processing of sold products; use of sold products; end-of-life treatment of sold products; downstream leased assets; franchises; investments.
Not all categories are relevant to every company. The first task is a screening to identify which categories are material to your business.
Why Scope 3 Matters Now
Three forces are making Scope 3 unavoidable for Thai companies:
- การเปิดเผยข้อมูลด้านสภาพภูมิอากาศตาม requires disclosure of Scope 1, 2 and material Scope 3 emissions as part of climate metrics. Climate and IFRS S2 disclosure depends on it.
- CBAM and export requirements push embedded-emissions data up the supply chain — your customers’ Scope 3 is your Scope 1.
- ESG ratings and investors increasingly score companies on value-chain emissions and reduction targets.
เอกสาร บัญชีก๊าซเรือนกระจก (GHG) that stops at Scope 2 no longer meets the bar.
How to Measure Scope 3
Scope 3 is estimated, not metered, so method and transparency matter as much as the number:
- Screen all 15 categories to find the material ones.
- Choose a method per category — spend-based, average-data, or supplier-specific (primary data), moving toward supplier-specific over time.
- Apply consistent factors — TGO and internationally recognised emission factors.
- Document assumptions and boundaries so the figure is auditable.
- Improve data quality each cycle, especially for your largest categories.
What to Disclose
Credible Scope 3 disclosure is about transparency as much as totals. Report which categories are included and excluded and why; the methods and data quality used; the emission factors applied; and any reduction targets. Under IFRS S2, this feeds directly into your climate metrics and targets. Disclosing a partial but honest Scope 3 inventory, with a plan to improve it, is far stronger than omitting it — and it should read identically across your Thai and English disclosure.
The Bilingual Dimension
For Thai issuers, Scope 3 figures, category boundaries and methodology notes must reconcile exactly across the Thai and English versions of the disclosure. A boundary described one way in Thai and another in English undermines the credibility of the whole inventory — which is why value-chain data is best handled within a single, reconciled bilingual ESG advisory กระบวนการแปล
Where Thai Companies Should Start
A full 15-category Scope 3 inventory is a multi-year journey, so the first cycle is about focus, not completeness. Start by identifying the two or three categories that dominate your footprint — for a manufacturer that is usually purchased goods and services; for a producer of energy-using products it is often use of sold products. Estimate these first with a spend-based or average-data method, be transparent that they are estimates, and begin engaging your largest suppliers for primary data. A focused, honest inventory of the material categories is far more useful — to investors, raters and your own decarbonisation planning — than a thin attempt to cover all fifteen at once.
Setting Scope 3 Reduction Targets
Measurement is only half the story; investors and ratings increasingly look for reduction targets that include the value chain. Frameworks such as the Science Based Targets initiative (SBTi) generally require companies to set Scope 3 targets where those emissions are a significant share of the total. Doing so means fixing a base year, choosing an appropriate metric (absolute or intensity), and — critically — building supplier engagement into the plan, because most of the reductions sit outside your direct control. For Thai exporters, credible value-chain targets are also becoming a commercial expectation from international customers, not just a disclosure line item.
Scope 3 will only grow in importance as IFRS S2 adoption deepens and value-chain expectations harden. The companies that start now — focusing on their material categories, being transparent about method, and reconciling the numbers across Thai and English — will be ready when disclosure of value-chain emissions moves from good practice to baseline expectation. Starting imperfectly, and improving each cycle, beats waiting for perfect data.
Common Scope 3 Mistakes to Avoid
Because Scope 3 is estimated and spans so many categories, it is easy to get wrong. The recurring mistakes:
- Double counting across categories — the same emissions captured twice, inflating the total.
- Ignoring the use phase — for many product companies, use of sold products is the largest category, yet it is frequently omitted.
- Staying spend-based forever — spend-based estimates are a fine starting point but a poor endpoint; the largest categories should move toward supplier-specific data.
- Skipping supplier engagement — most Scope 3 reductions sit with suppliers, so a plan that does not engage them cannot deliver.
- Changing boundaries silently — shifting which categories are included from year to year without explanation destroys comparability.
Avoiding these is less about sophistication than about discipline: define the boundary, document the method, and improve the data where it matters most.
📘 Free resource: Explore The FTSE 2026 Playbook Library — Othello’s ESG disclosure playbook plus focused editions for Thai banks, energy, property, healthcare, technology and more.
Related services from Othello International
Othello International is a Bangkok-based bilingual (EN↔TH) technical translation and ESG advisory firm. Related specialist services:
- บัญชีก๊าซเรือนกระจก (GHG) — Scope 1/2/3, TGO-aligned
- climate & IFRS S2 disclosure — TCFD four-pillar
- ESG disclosure translation — IFRS S2, GRI, FTSE-ready
- งานที่ปรึกษา ESG — ratings, climate, materiality
