A supplier questionnaire lands from BHP, Woolworths, or a tier-1 builder. Somewhere on page two it asks for your "Scope 1 and 2 emissions, calculated in accordance with the GHG Protocol Corporate Standard." If you've never heard of the GHG Protocol before that moment, you're not alone. Most regional Queensland businesses haven't. This article tells you what it is, why every major buyer asks for it, and what it means for your response.
The Question Prospects Always Ask First
Before we get to the GHG Protocol itself, here's the question Aethiro hears from almost every prospect: "Have you done this before for [BHP / Microsoft / Woolworths / Rio Tinto / Commonwealth Bank]?"
It's a fair question. Every major buyer's supplier questionnaire looks different. The format varies. The wording varies. The number of questions varies. BHP asks one way, Woolworths asks another, and Microsoft asks differently again. So it feels like each one needs specialist experience.
It doesn't. Strip the formatting away and every credible buyer questionnaire wants the same three things:
- Scope 1 and Scope 2 emissions, calculated under a recognised methodology.
- The methodology is the GHG Protocol Corporate Standard.
- Numbers that are documented, traceable, and defensible to an auditor.
The client changes. The methodology doesn't.
What matters in a supplier response is not whether your consultant has worked with your specific client before. What matters is whether your numbers are built on the right methodology. Once they are, the questionnaire is just a formatting exercise.
What the GHG Protocol Actually Is
The Greenhouse Gas (GHG) Protocol is the global standard for measuring and reporting greenhouse gas emissions. It was developed by the World Resources Institute (WRI) and the World Business Council for Sustainable Development (WBCSD), with the Corporate Standard first published in 2001 and revised in 2004. It is currently undergoing further revision, with a new draft expected for public consultation in mid-2026 (GHG Protocol).
In plain English, the GHG Protocol does four things:
- Defines the scopes. Scope 1 is the emissions you directly cause (diesel in your trucks, gas at your site). Scope 2 is the emissions from electricity you buy from the grid. Scope 3 is everything else in your value chain, from supplier emissions to freight, business travel, and the use of products you sell.
- Sets the boundaries. What's "your business" for emissions purposes. Equity share, financial control, or operational control. Most SMEs use operational control because it lines up with how they actually run the business.
- Names the gases. Carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and the fluorinated gases. All converted into carbon dioxide equivalent (CO2-e) using global warming potentials.
- Specifies the methodology. What records to keep, how to calculate, what to disclose, and what to do when data is incomplete.
That's the whole structure. You don't need to read 116 pages to comply with it. You need someone who already has.
Why Every Major Buyer Converges on It
Mining majors, supermarkets, banks, tech companies, and construction tier-1s all reference the GHG Protocol for the same reason: every other framework they're already complying with sits on top of it.
| Framework | Relationship to GHG Protocol |
|---|---|
| AASB S2 (Australia) | Mandates GHG Protocol Corporate Standard for all measurement, with a narrow exemption for NGER reporters using the NGER Determination for their NGER-reportable Scope 1 and 2 facilities. |
| IFRS S2 / ISSB (Global) | Same baseline methodology. AASB S2 is the Australian adoption. |
| SBTi (Science Based Targets) | Requires GHG Protocol-compliant inventories as the basis for any approved target. |
| CDP (formerly Carbon Disclosure Project) | Built on GHG Protocol categories. Used by most ASX 200 procurement teams to assess suppliers. |
| ISO 14064-1 | Aligns with the GHG Protocol Corporate Standard. Adds verification structure on top. |
When a buyer references "GHG Protocol Corporate Standard" in their questionnaire, they're not asking you to learn a new framework. They're asking you to use the one that everything else they're complying with already sits on top of.
The Australian Translation: GHG Protocol + NGA Factors
One thing that confuses Australian SMEs: the GHG Protocol is global, but the emission factors you use in calculations are local. In Australia, those are the National Greenhouse Accounts (NGA) emission factors, published annually by DCCEEW (Department of Climate Change, Energy, the Environment and Water).
The two work together, not in competition:
- GHG Protocol tells you what to count and how to structure it. Scopes, boundaries, methodology.
- NGA Factors tell you what intensity to multiply your activity data by. Litres of diesel, kWh of grid electricity, kilograms of LPG.
A compliant Australian inventory uses GHG Protocol structure with NGA factors as the calculation inputs. That's the standard backbone behind every credible supplier response in this country.
What Actually Varies Between Client Questionnaires
If the methodology is constant, what does change between, say, a BHP questionnaire and a Woolworths one? Three things:
- Format and field names. BHP uses one set of headings, Woolworths uses another. Same numbers underneath, different boxes to put them in.
- Boundary requests. Some buyers want emissions only from the work you do for them (project-level). Others want your whole-of-business inventory. The methodology to calculate either is the same. The cut you present is different.
- Verification level. Some accept self-reported numbers in the first year. Others require ISO 14064 verification or third-party assurance. This affects how the numbers are presented, not how they're calculated.
That's it. Everything else is window dressing. Once you have a GHG Protocol-aligned inventory with NGA factors, responding to any buyer's questionnaire is a translation exercise, not a recalculation exercise.
What This Means for You
If you've just been sent a supplier questionnaire and the GHG Protocol reference is the bit that triggered the Google search that led you here, the practical takeaway is short:
- You need a Scope 1 and Scope 2 inventory built to the GHG Protocol Corporate Standard, calculated using NGA emission factors.
- You probably need to think about Scope 3 if your customer is a Group 1 or Group 2 entity under AASB S2, because they will be asking you for that next.
- You need the numbers to be documented and traceable, not just a number in a spreadsheet.
You do not need a consultant who has worked with your specific client. You need a consultant who builds inventories to the underlying methodology every client already uses.
How Aethiro Handles This
Every Aethiro inventory is built to the GHG Protocol Corporate Standard, with Australian NGA emission factors, by an ISO 14064 Lead Verifier (TUV SUD). That's the same methodology every major buyer in your supply chain references, regardless of whether they're a mining major in the Bowen Basin, a supermarket in Sydney, or a bank in Melbourne. The questionnaire format changes. The methodology doesn't.
If you've received a supplier questionnaire and you're not sure where to start, the Supplier Data Response service handles the response from baseline to submission. If you're earlier in the cycle and need a fast carbon snapshot for a tender, the Tender-Ready Carbon Snapshot™ delivers in days. If you're a Group 2 entity preparing for AASB S2 from 1 July 2026, the AASB S2 & Mandatory Climate Reporting service builds your full disclosure to the GHG Protocol baseline and beyond.
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