Every Scope 3 calculation method comes with the same condition: if you can get data directly from your suppliers. Measured data from suppliers, such as their electricity use or product emissions, is the highest-quality input you can use.
In practice, even asking suppliers for data is hard. This article looks at why, and at strategies that work.
Why supplier data is hard to get
The first answer most companies hear is: “We’ve never calculated that.” Understanding why helps you plan.
1. Awareness and capability. Climate disclosure started with large companies, but their supply chains reach deep into small and mid-sized businesses. Asking a supplier that has never calculated its own Scope 1 and 2 for a product carbon footprint (PCF) is asking a lot.
2. Data sensitivity. Energy use and emissions intensity indirectly reveal production efficiency. It is natural for suppliers to hesitate before sharing that with customers.
3. No standard way of asking. Each customer asks for different items, units and boundaries. A supplier receiving requests in several formats has no clear standard to follow.
Three practical strategies
Rather than trying to collect perfect data in one go, build trust and work in stages.
Strategy 1: Start with a narrower request
Asking suppliers to “calculate and send your product carbon footprint” overwhelms most of them. Start with information they already have or can find easily.
For example, ask for “annual electricity and fuel use for the volume produced for us.” Suppliers can find this on utility bills or in equipment data, and it is enough for you to estimate emissions yourself. Lowering the bar this way makes a visible difference to response rates.
Strategy 2: Provide a standard template and calculation support
Sending a blank questionnaire is very different from sending a template with guidance and a calculation tool. A standard data collection template does two things: it reduces the work for suppliers, and it means the answers come back in a consistent format you can use.
Some leading companies go further and provide simple spreadsheets or web platforms where suppliers can calculate their own emissions.
Strategy 3: Focus on priority suppliers
Trying to get data from every supplier at once wastes resources. Use your category screening results to identify the suppliers behind your largest categories. In many companies, a relatively small share of suppliers accounts for most of Category 1 emissions.
With those priority suppliers, go beyond data requests: offer support for reducing emissions, or include sustainability terms when contracts are renewed.
When suppliers can’t provide data
Some suppliers won’t be able to respond, however good your strategy. For them, estimate emissions with the average-data or spend-based method. What matters is recording transparently that substitute data was used, and where it came from.
The GHG Protocol’s Scope 3 calculation guidance recommends documenting which category, why and which data source you used. For example: “For 30 Category 1 suppliers that did not respond, we applied industry-average emission factors from an LCI database. This covers about 15% of Category 1 emissions.”
Supplier data collection never ends
Supply chains change every year. New suppliers join, existing suppliers change their processes and emission factors are updated. Build a regular, annual collection process rather than a one-off exercise.
You can also raise data quality step by step: suppliers you estimated with average data in year one can be asked for measured data in year two or three. That is exactly what the GHG Protocol means when it recommends moving to more accurate methods over time.
In the end, supply chain carbon data is something you build together with suppliers. Treat it as a partnership that raises carbon management capability across the supply chain, not just as a data request and Scope 3 management becomes sustainable.
For background, see Scope 3 and Scope 3 calculation methods.