Learn how to approach Scope 3 emissions: identify hotspots, improve supplier data quality and build a practical process for value chain reporting.
Abstract
Scope 3 emissions are often the most complex part of a company’s carbon footprint because they depend on activities outside direct operational control, including suppliers, logistics, product use and end-of-life processes. Measuring them requires more than a calculation method: it requires value chain visibility, data quality and supplier engagement.
This article explains how companies can approach Scope 3 emissions in a practical way: by identifying hotspots, prioritising the most relevant categories, improving supplier data over time and building a repeatable process that supports credible reporting and better decision-making. In doing so, Scope 3 becomes a clear example of why ESG data must be structured, governed and scalable across the value chain.
Takeaways
- Scope 3 emissions are a value chain challenge, not only a carbon accounting exercise.
- Supplier data is often incomplete at the beginning, so companies need a progressive and prioritised approach.
- Hotspot analysis helps focus efforts where emissions and data gaps are most significant.
- Supplier engagement improves data quality over time and supports more credible reporting.
- Scope 3 management connects reporting, procurement, risk management and long-term decarbonisation.
What Scope 3 emissions include
Scope 3 emissions refer to indirect greenhouse gas emissions that occur across a company’s value chain, outside the boundaries of Scope 1 and Scope 2. They can include purchased goods and services, transportation, business travel, use of sold products, waste, investments and other upstream or downstream activities.
The GHG Protocol Corporate Value Chain (Scope 3) Standard identifies 15 categories of Scope 3 emissions and provides the main international reference for accounting and reporting value chain emissions. Its objective is not only to help companies calculate emissions, but also to understand where the most relevant impacts occur and where reduction efforts should be focused.
For many companies, Scope 3 represents the largest part of total emissions, especially when production, logistics, purchased materials or product use are significant. However, it is also the hardest part to measure because it depends on data that often sits outside the company.
This is why Scope 3 should not be approached as a purely technical calculation. It is a process that connects carbon accounting, procurement, supplier engagement and ESG data governance.
Why Scope 3 becomes difficult in practice
The main challenge with Scope 3 is not the definition itself. The difficulty lies in accessing reliable, comparable and updated data across the value chain.
Companies may need information from hundreds or thousands of suppliers, often operating in different geographies, sectors and maturity levels. Some suppliers may already track emissions; others may only provide basic activity data, while others may not have structured data available at all.
This creates three recurring problems:
data availability is uneven;
calculation methods may differ;
supplier responses are difficult to compare.
In practice, many companies start with estimates or spend-based data and then progressively improve data quality. This is a realistic approach, as long as assumptions are documented and improvements are planned over time.
The goal is not to achieve perfect Scope 3 data from the first reporting cycle. The goal is to build a process that becomes more accurate, more consistent and more useful year after year.
Start with hotspots, not with perfection
A practical Scope 3 process starts with hotspot identification. Instead of trying to collect detailed data for every activity immediately, companies should first understand which categories, suppliers or business activities are likely to drive the largest share of emissions.
Hotspots may emerge from purchased goods and services, logistics, energy-intensive suppliers, product use or specific materials. The relevant categories depend on the company’s sector, business model and value chain structure.
A hotspot-based approach helps companies avoid dispersing resources and focus supplier engagement where it matters most. It also allows ESG and procurement teams to identify where improved data quality would make the greatest difference.
This is particularly important for companies that are still building their ESG data processes. Starting from hotspots makes Scope 3 more manageable and prevents the process from becoming too broad too early.
Supplier engagement is not just data collection
Supplier engagement is often treated as a questionnaire exercise. In reality, it is much more than that.
To improve Scope 3 reporting, companies need suppliers to understand what data is required, why it matters and how it will be used. This requires clear communication, consistent requests and realistic expectations.
The Science Based Targets initiative highlights supplier engagement as a key lever for addressing Scope 3 emissions, especially when companies are setting or implementing value chain targets. Its guidance focuses on evaluating and setting supplier engagement targets, implementing initiatives and monitoring progress.
For companies, this means supplier engagement should be structured over time. The first step may be collecting basic data. The next may be improving accuracy. Later, the focus may shift to reduction initiatives, supplier targets or collaboration on specific hotspots.
Engagement therefore becomes a process of maturity building, not a one-off request.
Data quality improves progressively
Scope 3 data quality rarely improves all at once. It usually evolves through stages.
At the beginning, companies may rely on estimates, secondary data or spend-based calculations. As supplier engagement improves, they can move toward activity-based data, supplier-specific information and more accurate methodologies.
A good Scope 3 process should document:
which data sources were used;
where estimates were necessary;
which assumptions were applied;
how data quality is expected to improve.
This approach makes Scope 3 reporting more transparent and more defensible, even when data is not perfect. It also helps companies demonstrate progress over time, which is increasingly important when stakeholders look not only at emissions figures, but also at the credibility of the process behind them.
Why Scope 3 is becoming a governance issue
Scope 3 management does not sit only within sustainability teams. It requires collaboration between ESG, procurement, finance, operations and risk management.
Procurement plays a central role because many Scope 3 categories depend on supplier information. Finance may be involved when emissions data needs to connect with purchasing, spend or reporting systems. Risk and governance teams become relevant when data quality, auditability and supplier engagement need to be monitored over time.
In this sense, Scope 3 is not only an emissions topic. It is a governance challenge around data, suppliers and decision-making. Companies need to define who owns supplier-related emissions data, how information is collected and validated, and how improvements are tracked over time.A structured approach helps connect Scope 3 measurement with procurement, risk management and ESG reporting processes. This makes emissions data more useful not only for disclosure, but also for identifying priorities, engaging suppliers and supporting long-term decarbonisation decisions.
Mini-checklist: starting your Scope 3 process
✅ Identify which Scope 3 categories are most relevant for your business.
✅ Map where supplier data is needed and where data gaps are most significant.
✅ Start with hotspots instead of trying to measure everything at once.
✅ Define clear supplier data requests and make them consistent over time.
✅ Document assumptions, methodologies and data quality limitations.
✅ Use each reporting cycle to improve data accuracy and supplier engagement.
Explore related ESG Guides
To continue building a structured approach to ESG data, suppliers and reporting, you may find these ESG Guide articles useful:
CSDDD explained: what due diligence means and how to operationalise it across suppliers
How supplier due diligence helps companies structure risk, controls and traceability across the value chain.
ESG Data Collection: How and Where to Take Action
A practical guide to building reliable and traceable ESG data flows across organisations and value chains.
https://www.synesgy.com/en/esg-guide/esg-data-collection-how-and-where-to-take-action/
Double materiality explained: how companies identify their ESG priorities
How companies can define ESG priorities and focus reporting on what truly matters.
ESRS explained: what companies must report and how to prepare
A practical overview of how ESRS translate reporting requirements into data, governance and evidence.
https://www.synesgy.com/en/esg-guide/enesg-guideesrs-readiness-how-to-prepare/
FAQ
What are Scope 3 emissions?
Scope 3 emissions are indirect greenhouse gas emissions that occur across a company’s value chain, outside Scope 1 direct emissions and Scope 2 purchased energy emissions. They include upstream and downstream activities such as suppliers, logistics, business travel and product use.
Why are Scope 3 emissions difficult to measure?
They are difficult because much of the data comes from suppliers or external partners. Data may be incomplete, inconsistent or based on different methodologies, especially at the beginning of the process.
Should companies wait until supplier data is perfect?
No. A practical approach starts with available data, identifies hotspots and improves quality over time. What matters is documenting assumptions and building a repeatable process.
How can supplier engagement improve Scope 3 reporting?
Supplier engagement helps companies collect better data, clarify expectations and progressively move from estimates to more accurate supplier-specific information.
