Supplier Carbon Data Missing? A Practical Guide to Using Secondary Data in a PCF

A practical guide to secondary data, supplier requests, data-quality checks, and transparent customer reporting

Short answer: Missing supplier carbon data does not always prevent a company from calculating a Product Carbon Footprint. A preliminary calculation may use suitable industry or database data, provided that the substitute is representative, traceable, and clearly disclosed. Generic data must not be presented as supplier-specific evidence, and important gaps should have an improvement plan.

A customer has requested the Product Carbon Footprint, or PCF, of one of your products.

Your engineering team has the Bill of Materials. The factory can provide electricity and production records. However, several suppliers cannot provide carbon data for their materials or components.

Some suppliers have never calculated a PCF. Others provide a company-wide emissions report without product-level information. Some send a carbon number but cannot explain what it includes.

Does the entire project have to stop?

Usually, no.

A credible PCF does not require pretending that every input is perfect. It requires using the best appropriate information available, documenting the choices made, and improving the most important data gaps over time.

What does “supplier carbon data” mean?

The term can refer to several different types of information.

Supplier-specific PCF

A supplier-specific PCF is a carbon footprint for a defined material or component supplied to your company.

It should identify:

• Material or product assessed
• Calculation unit, such as one kilogram or one component
• Production location
• Reporting period
• Life-cycle stages included
• Calculation method
• Important assumptions and exclusions
• Independent review or verification status

A carbon number without this context is difficult to use responsibly.

Supplier activity data

A supplier may not have calculated a PCF, but it may be able to provide the physical information needed for a calculation, such as:

• Electricity consumption
• Fuel consumption
• Production volume
• Material inputs
• Recycled content
• Process losses
• Transport information

This information can be highly valuable because it allows a calculation to use the supplier’s actual operating conditions together with suitable emissions reference data.

Supplier attributes

A supplier may be unable to provide detailed production data but still be able to confirm:

• Production country
• Production technology
• Material grade
• Primary or recycled production route
• Recycled-content percentage
• Supplier location
• Factory or furnace type

These details help identify a more representative secondary dataset.

Secondary data

Secondary data comes from sources other than the specific supplier’s measured operations. It may include:

• Life-cycle inventory databases
• Industry associations
• Government publications
• Peer-reviewed studies
• Recognised sector datasets
• Published Environmental Product Declarations

Secondary data is not automatically poor-quality data. Its usefulness depends on how well it represents the material, technology, geography, reporting period, and calculation scope being assessed.

Missing supplier data does not mean “use any average”

Using secondary data is a normal part of many PCF studies. The professional judgement lies in selecting a suitable substitute.

Suppose a BOM contains two kilograms of aluminium. Available datasets may include:

• Global-average primary aluminium
• Regional primary aluminium
• Recycled aluminium
• Extruded aluminium profile
• Rolled aluminium sheet
• Aluminium produced using a specific electricity mix

All of these may contain the word “aluminium,” but they do not represent the same product or production route.

A suitable substitute should be assessed against at least five questions.

1. Is it the same material or process?

“Plastic,” “steel,” and “aluminium” are usually too broad.

Where possible, match the actual material grade, product form, and production route. ABS resin is not interchangeable with polypropylene. Stainless steel is not interchangeable with carbon steel. Aluminium sheet may require additional processing beyond aluminium ingot production.

2. Is the technology representative?

The same material can be produced using different technologies.

Primary and recycled metal production can have substantially different energy requirements. A supplier using an electric arc furnace may not be well represented by data for a blast-furnace route.

3. Is the geography representative?

Electricity generation, fuel use, transport systems, and industrial technology vary by country and region.

A European dataset may not represent production in China, India, or another manufacturing region. Global-average data may be acceptable for an early estimate, but a closer geographical match is preferable when location is known and materially affects the result.

4. Is the data recent enough?

Industrial technology and electricity systems change over time.

Record the reference year and dataset version. Older data may still be usable, but its age should be considered when assessing representativeness.

5. Does it cover the same stages?

One supplier value may cover only activities inside the supplier’s factory. Another dataset may include raw-material extraction, upstream processing, and transport.

These values cannot be substituted without checking what each one includes.

In plain language, ask:

Does this number describe the same product, made in a reasonably similar way and place, during a relevant period, and does it include the same parts of the supply chain?

A practical hierarchy for missing supplier data

Use the most representative information available, not simply the most specific-looking number.

Option 1: Compatible supplier-specific PCF

Use a supplier PCF when its product, unit, calculation scope, period, and methodology are compatible with your calculation.

Check:

• Whether it describes the exact material or component purchased
• Whether the result is per kilogram, per item, or another unit
• Which life-cycle stages are included
• Which factory and reporting period it represents
• How shared factory emissions were allocated
• How recycled materials and production losses were treated
• Which calculation method was used
• Whether independent review was completed

Verification can increase confidence, but verification alone does not make an incompatible result usable.

Option 2: Supplier activity data

When a supplier cannot provide a complete PCF, request physical production data instead.

For example:

If you cannot provide a verified PCF, can you provide electricity, fuel, production volume, material input, recycled content, and production location for this material?

This may support a more representative calculation than an unexplained supplier carbon number.

Option 3: Supplier attributes plus secondary data

If detailed production data is unavailable, use known supplier attributes to select a closer reference.

For example:

• Material: aluminium sheet
• Production country: China
• Recycled content: 30%
• Production route: not confirmed
• Reporting year: 2025

This is more transparent than selecting a generic global aluminium value without recording any supplier characteristics.

Option 4: Representative industry data

When only the material and quantity are known, use a suitable industry or database average.

Record:

• Dataset name
• Provider
• Version
• Reference year
• Geography
• Technology
• Unit
• Included stages
• Reason for selection

Option 5: Conservative screening proxy

When information is extremely limited, use a clearly labelled screening assumption or range.

Do not present it as a final supplier result. Record what information is needed to replace it.

Supplier-specific data is not automatically better

A supplier may send a spreadsheet stating:

Carbon footprint: 1.82 kg CO2e

That number may look precise, but it is not usable until you know:

• Is it per kilogram or per component?
• Which product grade does it represent?
• Which production site?
• Which reporting year?
• Does it include raw-material production?
• Does it include transport?
• Were production losses included?
• Which calculation method was used?
• Was renewable electricity included?
• Was the result independently reviewed?

An unexplained supplier number can be less defensible than a transparent secondary dataset that closely matches the material and production region.

The relevant principle is:

Use the most representative, complete, consistent, and traceable data available for the intended use.

Prioritise the gaps that could change the result

You do not need to wait until every supplier provides perfect information.

Start by identifying which materials and components are likely to contribute most to the product footprint.

A practical process is:

1. Calculate an initial result using documented secondary data.
2. Identify materials or components with the largest estimated contribution.
3. Assess which results are based on weak or uncertain data.
4. Contact suppliers associated with both high impact and low data quality.
5. Replace estimates when suitable supplier information becomes available.
6. Recalculate and record the change.

This is more effective than sending the same detailed questionnaire to every supplier.

Purchasing spend can help identify important suppliers, but it should not be the only prioritisation method. A low-cost material may still create substantial emissions, while an expensive component may have a relatively low carbon contribution.

Use expected emissions contribution, strategic importance, data uncertainty, and customer requirements together.

Example: aluminium supplier data is missing

A manufacturer is calculating the PCF of one industrial enclosure containing two kilograms of aluminium sheet.

The supplier cannot provide a PCF.

The manufacturer knows:

• Material form: aluminium sheet
• Quantity: 2 kg per product
• Supplier location: China
• Recycled content: not confirmed
• Transport: truck and sea freight
• Production technology: not confirmed

A defensible first approach is to:

1. Select a documented secondary dataset reasonably representative of aluminium sheet produced in the relevant region.
2. Record that supplier-specific production technology and recycled content are unavailable.
3. Calculate a preliminary result using the selected reference.
4. Test an alternative scenario using another plausible production route or recycled-content assumption.
5. Check whether the difference materially affects the total product result.
6. Prioritise the aluminium supplier if the material is a significant contributor.
7. Replace the estimate when compatible supplier data becomes available.

The report could state:

Aluminium production was modelled using regional secondary data because supplier-specific production and recycled-content information was unavailable. The aluminium input represents a significant part of the preliminary result and has been prioritised for data improvement.

What should you ask the supplier for?

A staged request usually receives better responses than a long technical questionnaire.

Basic product information

Ask for:

• Material or component name
• Grade or specification
• Production country
• Production site
• Quantity or unit
• Recycled content
• Reporting period

Existing carbon information

Ask whether the supplier has:

• Product-specific PCF
• Environmental Product Declaration
• Life-cycle assessment
• Verified carbon report
• Customer-specific carbon calculation
• Facility-level emissions inventory

A facility inventory is not the same as a product footprint, but it may provide useful calculation inputs.

Production activity data

If no PCF exists, ask for:

• Electricity consumption
• Fuel and process-heat consumption
• Production output
• Raw-material inputs
• Scrap and yield
• Direct process emissions
• Allocation method
• Packaging and outbound transport data

Use a consistent reporting period wherever possible.

Supplier request email template

Subject: Product carbon data request for [material/component]

Dear [Supplier name],

We are preparing a Product Carbon Footprint for [product name] in response to a customer requirement.

Please provide any available product carbon information for the following supplied material or component:

• Material or component: [description]
• Part number or grade: [reference]
• Production site: [if known]
• Requested unit: [for example, kg CO2e per kg or per component]
• Preferred reporting period: [year]

If a product-specific carbon footprint is available, please also provide:

• Included life-cycle stages
• Calculation method or standard
• Reporting period and production location
• Main data sources and assumptions
• Verification status
• Supporting report or declaration

If a product-specific footprint is not available, please provide any available information on:

• Production country and technology
• Electricity and fuel consumption
• Production volume
• Material inputs and recycled content
• Production scrap or yield

Please indicate which information is measured, estimated, or based on industry averages.

Thank you.

How to assess a supplier PCF before using it

Receiving a supplier PCF is not the end of the review. Check whether it can be integrated into your own calculation.

If the supplier PCF is not fully compatible, determine whether part of the underlying activity data can still be used.

Document every substitution

For each missing supplier input, maintain a simple data-gap register.

This register helps answer:

• Where did the number come from?
• Why was it selected?
• How important is the uncertainty?
• What will be done to improve it?

It also prevents temporary estimates from becoming permanent assumptions.

How to communicate the result to a customer

A customer-facing report should explain:

• Which parts use supplier-specific data
• Which parts use company data
• Which parts use secondary data
• Why secondary data was selected
• Which gaps could materially affect the result
• Whether the result is preliminary or independently reviewed
• When important data will be updated

Suitable wording could be:

The preliminary PCF uses primary manufacturing data for our production site. Supplier-specific carbon data was unavailable for three material inputs, so documented secondary datasets were selected based on material type, production geography, and available technology information. These substitutions and their limitations are listed in the data-quality register. The aluminium input is the highest-priority area for improvement.

Avoid statements such as:

• “All values are based on supplier data” when database averages were used
• “Verified PCF” when only individual inputs were verified
• “Actual emissions” when significant values are estimated
• “ISO 14067 certified” without a defined and completed conformity process
• “Complete supplier coverage” when suppliers provided only company-level reports

Preliminary PCF versus customer-ready PCF

Missing supplier data affects different uses differently.

Internal screening

Secondary data is often sufficient to identify hotspots and prioritise improvement.

Initial customer response

A documented preliminary result may be acceptable if the customer understands the scope, data sources, limitations, and update plan.

Procurement questionnaire

Check the customer’s instructions. Some questionnaires accept secondary data if it is identified; others request supplier-specific or reviewed evidence.

Public environmental claim

A public claim requires greater caution. Missing supplier data, incompatible comparisons, or unexplained assumptions can make a precise claim misleading.

Independent verification

A verifier may accept justified secondary data depending on the applicable method, significance of the input, data-quality requirements, evidence, and intended use. Secondary data does not automatically prevent verification, but weak selection and poor documentation can.

Common mistakes

• Waiting for perfect supplier data before starting
• Using the first database result
• Selecting the lowest available value
• Treating a company carbon inventory as a product PCF
• Mixing incompatible supplier results
• Replacing secondary data without checking compatibility
• Asking every supplier for everything
• Hiding estimates behind excessive precision
• Failing to record temporary assumptions

A practical workflow

When supplier carbon data is missing:

1. Confirm the product, BOM version, calculation unit, production site, and intended use.
2. Identify materials and components without supplier data.
3. Select representative secondary data for an initial calculation.
4. Record its source, version, geography, technology, year, unit, and included stages.
5. Calculate a preliminary result and identify likely hotspots.
6. Prioritise suppliers based on expected impact and data uncertainty.
7. Ask first for existing PCFs, then for activity data or supplier attributes.
8. Review supplier information for compatibility before using it.
9. Replace temporary values and record how the result changes.
10. Explain remaining substitutions and limitations in the customer report.
11. Maintain a dated improvement plan for future updates.

Frequently asked questions

Can a PCF use secondary data?

Yes. Secondary data is commonly used where primary supplier information is unavailable or impractical to collect. It should be suitable for the material or activity, traceable to its source, and disclosed appropriately.

Does ISO 14067 require data from every supplier?

A credible ISO 14067-based study requires appropriate data and transparent treatment of data quality, but this does not necessarily mean obtaining a verified PCF from every supplier. Requirements depend on the calculation scope, applicable rules, significance of the input, intended use, and review process.

Can I use an Environmental Product Declaration from a supplier?

Potentially. Check that it covers the actual product, plant, period, declared unit, and relevant life-cycle stages. Also check whether its rules and modelling choices are compatible with your PCF.

Can a supplier’s company carbon report be used?

It may provide useful facility-level inputs, but it is not automatically a product footprint. A documented method is needed to assign facility emissions to the supplied product.

Should I always replace secondary data with supplier data?

No. Replace it only when supplier data is sufficiently complete, representative, and compatible. An unexplained supplier number is not automatically an improvement.

What if the supplier refuses to provide confidential production data?

Ask for less sensitive alternatives, such as a product-level PCF, verified declaration, production country, technology, recycled content, renewable-electricity evidence, or aggregated activity data. Record what could and could not be obtained.

How often should supplier data be updated?

Set a review cycle based on customer requirements, reporting rules, and material changes. Update sooner when the supplier, production site, material grade, electricity source, manufacturing process, or recycled content changes significantly.

Conclusion

Missing supplier carbon data does not automatically stop a Product Carbon Footprint.

Start with the best representative information available. Document why it was selected. Identify which assumptions could materially affect the result. Then improve those inputs through focused supplier engagement.

The objective is not to claim that every number is primary data. It is to produce a calculation that another professional can understand, reproduce, challenge, and improve.

A trustworthy result should make four things clear:

• What information came from the supplier
• What information came from your own operations
• What information was estimated using secondary data
• What will be improved next

References and further reading

• ISO 14067:2018 — Greenhouse gases: Carbon footprint of products
• GHG Protocol Product Life Cycle Accounting and Reporting Standard
• GHG Protocol Scope 3 Calculation Guidance
• WBCSD Partnership for Carbon Transparency
• European Commission Environmental Footprint Methods