Scope 3 Emissions: Where Supply Chain ESG Data Goes Wrong

Introduction

When CSRD requires companies to report Scope 3 emissions — the emissions that occur in their value chain, both upstream and downstream — it's asking them to report on data they don't own, from organisations they don't control, using methodologies those organisations may not have implemented.

This is the hard problem of corporate ESG reporting. And it's why Scope 3 is where most companies' climate programmes break down.

What Scope 3 Actually Covers

The GHG Protocol defines 15 Scope 3 categories. For most companies, the most material are:

• Category 1 — Purchased goods and services: the emissions generated in producing everything you buy
• Category 4 — Upstream transportation: emissions from transporting goods to you
• Category 11 — Use of sold products: emissions generated when customers use your products (critical for automotive, electronics, energy)
• Category 12 — End-of-life treatment: emissions from disposing of your products
• Category 15 — Investments: emissions from your investment portfolio (critical for financial institutions)

CSRD (specifically ESRS E1) requires disclosure of Scope 3 emissions where material under double materiality. For most manufacturing, retail, and financial services companies, Scope 3 is material — typically representing 70–90% of total emissions.

Why Scope 3 Data Collection Fails

Suppliers don't measure their emissions

The fundamental problem: you can only calculate your Scope 1 (purchased goods and services) from supplier-specific data if your suppliers measure and report their own Scope 1 and 2 emissions. The majority don't. This means you're dependent on industry-average emission factors — which are available from databases like ecoinvent and DEFRA — but which produce estimates rather than actual data.

No systematic supplier engagement

Many companies are waiting for suppliers to volunteer their emissions data. This never works. Effective Scope 3 programmes require a structured supplier engagement process: identifying priority suppliers (typically those representing 80% of spend), requesting specific data, providing templates, and following up.

Category selection errors

Companies frequently miscategorise Scope 3 emissions or omit material categories because of the complexity of the 15-category framework. Category 11 (use of sold products) is particularly commonly omitted — despite being material for many sectors — because it requires lifecycle assessment thinking.

No documented methodology

Even when Scope 3 data is collected, it often lacks a documented methodology — which means it can't be assured and won't survive regulatory scrutiny. ESRS requires you to describe your approach to Scope 3 data collection, the emission factors used, and the basis for materiality assessment.

The Minimum Viable Scope 3 Approach for CSRD

For companies in CSRD scope who don't have mature Scope 3 programmes, the minimum viable approach is: identify your material Scope 3 categories using the materiality assessment process; calculate spend-based estimates for Categories 1–8 using DEFRA or ecoinvent factors; establish a supplier data request process for your top 20 suppliers by spend; document your methodology, assumptions, and data quality; and commit to improving your data quality year-on-year.

This approach won't produce perfect data — but it produces a defensible, improvable baseline that satisfies ESRS requirements and passes assurance review.

Getting Support

Chabil Consulting helps companies build Scope 3 data collection frameworks and CSRD-compliant disclosure. Our Scope 3 programme runs 6–8 weeks and produces a methodology document, supplier engagement process, and baseline Scope 3 inventory.