Australia / Guides / A customer asked for your emissions data: what to send and why
Australia · guideA customer asked for your emissions data: what to send and why
The short answer
The request usually lands because your customer is a Group 1 or Group 2 reporter under AASB S2 and your company sits in their Scope 3, Category 1 ("purchased goods and services") — meaning your own operational emissions become a line item they have to measure, whether or not you report anything yourself. AASB S2 requires those customers to measure emissions consistent with the GHG Protocol Corporate Standard, and the GHG Protocol's own guidance names the data a supplier is best placed to supply: activity data (units of a product or service delivered), energy consumption, fuel use, and — when nothing more specific exists — total spend by category. A defensible response pack answers with real records rather than estimates wherever records exist, states the calculation method used for anything that is not, and keeps the underlying data traceable back to invoices, meter readings or fuel receipts so the number survives a later audit. Banks, insurers and other financiers ask a close cousin of the same questions for the same underlying reason: their own financed-emissions and credit-risk disclosures run on the same GHG Protocol categories.
Key facts — verified dates on each
Why the request reaches a company too small to report itself
AASB S2 phases mandatory climate reporting in three groups by size, and a business well below every Group 3 threshold can still receive a formal data request from a customer that is inside the regime. That is because a reporting entity's Scope 3 emissions are, by definition, emissions that happen in someone else's operations — a supplier's factory, a contractor's van, a service provider's office. The reporting entity has to measure them anyway, and the only way to measure another company's emissions accurately is to ask that company for its numbers.
For most small and mid-sized suppliers, the relevant category is Scope 3 Category 1, "purchased goods and services" — everything the customer buys from them. A caterer, a logistics contractor, a software vendor and a component manufacturer all sit in the same category from the customer's point of view, even though the underlying activity looks nothing alike. The size mismatch is the point: a Group 1 company's reporting obligation reaches every supplier on its purchase ledger, regardless of that supplier's own reporting status.
What the request typically asks for
Requests vary in format — a spreadsheet, a supplier portal, a CDP-style questionnaire, or a plain email — but they converge on the same handful of data types, because these are what the GHG Protocol's own calculation guidance identifies as usable inputs. In descending order of how directly they map to actual emissions: activity data (units of product or service actually delivered, e.g. tonnes shipped, kilowatt-hours of a manufactured good, hours of a service performed), energy consumption (electricity and other purchased energy used to produce what was supplied), fuel use (litres or units of fuel burned directly in delivering the goods or service), and spend by category (the dollar value of what was purchased, used only when better data is not available).
A request rarely demands all four at once. Most start with whichever is easiest for the requester to plug into their own model — commonly spend data, because it is the one figure both sides already have on an invoice — and get more specific over time as the relationship matures or the customer's own reporting group advances past its first year.
- Activity data — units of product/service actually supplied
- Energy data — electricity and purchased energy consumed to deliver it
- Fuel data — litres or units of fuel burned directly
- Spend data — dollar value by purchase category, the fallback when nothing more specific exists
The GHG Protocol basis behind the request
AASB S2 does not invent its own emissions-measurement methodology. It requires an entity to measure greenhouse gas emissions in accordance with the Greenhouse Gas Protocol: A Corporate Accounting and Reporting Standard, unless a jurisdictional authority or exchange requires a different basis — which is why a customer's request almost always maps cleanly onto GHG Protocol terminology (Scope 1, 2, 3; the fifteen Scope 3 categories) rather than an AASB-specific framework.
The GHG Protocol's Scope 3 guidance sets out four calculation approaches for Category 1, ranked from most supplier-specific to most generic: the supplier-specific method (using a supplier's own product-level cradle-to-gate emissions data), the hybrid method (blending supplier-provided activity or energy data with secondary emission factors), the average-data method (activity data — mass, units, hours — multiplied by an industry-average emission factor), and the spend-based method (dollar spend multiplied by an average emission factor per dollar for that category). A supplier who can hand over real activity or energy data lets the customer move up that ranking, which is generally why the request is framed as a request for records, not an estimate.
Because the standard is method-agnostic about how a supplier arrives at its numbers, a response built on actual records — meter readings, fuel receipts, production logs — carries more weight than a modelled estimate, but a well-documented estimate using a recognised method is still usable input; the requirement is that the method is stated, not that every figure be a direct measurement.
What a defensible response pack contains
A response that holds up under a later audit or assurance review is built the same way any other compliance file is built: the figures, the method behind each figure, and the record each figure traces back to, kept together rather than sent as a single unsupported number in an email reply.
In practice that means: the requested data points themselves (activity, energy, fuel or spend, whichever was asked for), a short note on which calculation approach was used for each figure and why, the underlying records the figures were drawn from — utility bills, fuel invoices, production or delivery logs, purchase ledgers — organised so a reviewer can trace a reported number back to its source, and the reporting period the data covers, matched to the customer's own financial year where that has been specified. Consistency across periods matters as much as accuracy in any single period, because a customer's year-on-year Scope 3 trend depends on suppliers reporting on a comparable basis each time they are asked.
- The figures requested — activity, energy, fuel or spend, matched to what was actually asked
- The calculation method used for each figure
- Source records the figures trace back to — bills, invoices, logs, ledgers
- The reporting period, aligned to the customer's financial year where specified
Why banks and insurers ask the same questions
A supplier that has never received a customer's Scope 3 request may still encounter the same data ask from a bank or insurer, for a related but distinct reason. Banks measuring their own financed emissions — the emissions associated with the loans and investments on their book — treat a business borrower's operational emissions as a Scope 3, Category 15 item on the bank's own ledger, calculated using the same GHG Protocol categories and, for financial institutions specifically, the Partnership for Carbon Accounting Financials (PCAF) methodology built on top of them. Insurers assessing underwriting risk, and increasingly loan officers assessing credit risk, ask a close variant of the same question because a business's energy intensity and emissions trajectory are treated as inputs to transition-risk pricing.
The practical consequence is that a business preparing one clean, well-sourced emissions data pack — built once, to the GHG Protocol categories, from real records — tends to answer a customer's Scope 3 request, a bank's financed-emissions questionnaire, and an insurer's underwriting questionnaire from the same underlying file, rather than needing three separate exercises.
The figures, and when we checked them
These numbers change by year or by notification. Each one shows the date we last verified it against the source — if that date looks old, check the source before relying on it.
Questions on this
Why did a large customer ask a small supplier for its emissions data?
The customer is very likely a Group 1 or Group 2 reporter under AASB S2, and the supplier's operational emissions fall inside the customer's Scope 3 (usually Category 1, purchased goods and services). AASB S2 requires the customer to measure that Scope 3 footprint against the GHG Protocol, and the only way to do that accurately is to ask each supplier directly.
Does receiving this request mean the supplier itself has to comply with AASB S2?
No. AASB S2's own reporting obligations apply only to entities that meet the Group 1, 2 or 3 thresholds. A supplier below those thresholds has no AASB S2 filing obligation of its own — the request is coming from the customer's obligation, not the supplier's.
What kind of data is usually the easiest to provide first?
Spend data by purchase category is usually the easiest, because both sides already have it on invoices. Activity data (units delivered), energy consumption and fuel use produce a more accurate answer and let the customer use a more specific GHG Protocol calculation method, but they take more work to compile.
What GHG Protocol standard is AASB S2 built on?
AASB S2 requires emissions to be measured in accordance with the Greenhouse Gas Protocol: A Corporate Accounting and Reporting Standard, unless a jurisdictional authority or exchange requires a different basis.
Is Scope 3 disclosure required in a reporting entity's very first year under AASB S2?
No. AASB S2 gives relief in the first annual reporting period an entity applies the standard — Scope 3 disclosure and comparative Scope 3 information are not required until the second annual reporting period.
What makes an emissions data response defensible rather than just a number in an email?
The figures should be paired with the calculation method used and the underlying records — bills, invoices, logs, ledgers — that the figures trace back to, covering a stated reporting period. That combination is what lets a reviewer, or a later assurance practitioner, verify the number rather than take it on trust.
Why would a bank or insurer ask the same kind of question as a customer?
Banks calculating financed emissions and insurers assessing transition risk both draw on the same GHG Protocol categories a customer's Scope 3 request uses. A business's operational emissions become an input to the bank's or insurer's own risk and disclosure calculations, for reasons parallel to — but separate from — a customer's supply-chain Scope 3 obligation.
Who reviews or verifies an emissions data pack sent to a customer?
The data pack itself is a preparation exercise; there is no requirement for third-party assurance on data sent supplier-to-customer. Assurance obligations sit with the AASB S2 reporting entity itself, which uses AUASB-registered assurance practitioners for its own disclosures — the supplier's pack simply needs to be traceable and consistent enough to support that later review if the customer's assurance practitioner asks to see it.
Primary sources
- GHG Protocol — Category 1: Purchased Goods and Services (Technical Guidance for Calculating Scope 3 Emissions)
- AASB — Australian Sustainability Reporting Standard AASB S2 (September 2024), Appendix C effective date and transition
Last reviewed 2026-08-15. Statutes and schedules change — the sources above are authoritative, this page is orientation.
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