Industry-average or supplier-specific? What your Scope 3 emissions number is really telling you

If you have started reporting on Scope 3 emissions, chances are your first number came from an industry-average emission factor. You took a spend figure or an activity quantity, multiplied it by a published factor for "steel" or "freight" or "professional services," and arrived at a total. It's the standard entry point, and for good reason: it's fast, it's methodologically sound, and it gets you a defensible baseline while the rest of your reporting program catches up.

But it's worth being honest about what that number is really telling you, and, just as importantly, what it is not.

Industry averages are a legitimate starting point

There is a persistent myth in Scope 3 circles that average-based data is a lesser, temporary compromise, something to apologise for in a footnote. It isn't. The GHG Protocol explicitly recognises average-data methods as valid, and for most reporting companies facing their first mandatory disclosure cycle, they are the only realistic way to get complete category coverage in the time available.

An industry-average factor tells you, credibly, the approximate emissions intensity of a category of spend or activity. Applied consistently, it gives you a defensible total, a like-for-like baseline you can track year on year, and a number that will survive assurance review, provided it's applied correctly and the boundary and methodology are documented. For companies under AASB S2 or similar mandatory regimes, that combination of speed and defensibility matters. Nobody should be talked out of starting here.

What it can't tell you

The limitation isn't in the number's validity; it's in its resolution.

An industry-average factor describes the average supplier in a category, not any of your actual suppliers. Two suppliers in the same spend category can have wildly different emissions intensities depending on their energy mix, process efficiency, or how far along their own decarbonisation journey they are. Average-based data collapses that variation to a single figure, which means:

It can't show you where your actual hotspots sit within a category, only that the category itself is large or small. It can't detect supplier improvement. If a supplier switches to renewable electricity or redesigns a product to cut embodied carbon, an average factor won't move because it was never measuring that supplier in the first place. It gives you little to act on. A category total tells you what is large; it does not tell you why, or which lever to pull. And increasingly, it invites scrutiny. As assurance requirements tighten and stakeholders get more literate in Scope 3 methodology, "average-based, no supplier engagement" reads less like a baseline and more like a plateau.

This is the ceiling: an industry-average number can be accurate and still be undecisive. It answers, "how much," not "where" or "what next."

Supplier-specific data is the next step, not a correction

You might read the above as "industry averages were wrong; supplier data is right." That framing does more harm than good, it makes the transition feel like an admission of past error rather than what it is: a maturity steps every serious reporting program eventually takes.

Supplier-specific data, primary data collected directly from suppliers and ideally verified, does what averages structurally cannot. It shows you actual variation across your supply base, so you can see which suppliers are genuinely lower-carbon and which are dragging the category average up. It rewards supplier action, so a decarbonisation investment by a supplier shows up in your number, which is exactly the incentive structure you want if you are asking suppliers to engage. It sharpens category totals into supplier-level and even product-level hotspots, which is where procurement, engineering, and sustainability teams can make decisions and move the needle. And it holds up better under scrutiny because it's traceable to a specific source rather than a published, generic coefficient.

None of this requires 100% supplier coverage on day one. Most companies that make this transition well do it selectively, starting with their largest categories by emissions or spend, or their most strategically important suppliers, and building supplier-specific coverage outward from there. A hybrid inventory, part average, part supplier-specific, applied deliberately, is usually the realistic middle state for several reporting cycles. That is not a compromise either. It's what maturity looks like in practice.

Who actually needs this and it's probably not who you think

It's tempting to file supplier-specific data under "nice to have if you're already ahead of the pack", something for companies whose supply chain genuinely outperforms the category average and wants that reflected in the number. That's a real benefit but treating it as the main reason to make the move undersells how many reporting companies need this regardless of where they sit relative to the average.

If you've made a public reduction target, net zero, science-based, or otherwise, an industry-average inventory can never show you got there. The factors don't move when a supplier decarbonises, because they were never measuring that supplier to begin with. A target you can't evidence with your own numbers isn't a target you can defend, and at this point a stated target is closer to the norm than the exception.

The same pressure is building on the assurance side. As mandatory regimes like AASB S2 move from limited to reasonable assurance over time, a Scope 3 number built entirely on generic, published coefficients is going to draw more questions, not fewer. Supplier-specific data is what lets you answer, "how do you know" with something more than "that's what the category average says."

And there's a cascade effect worth naming: reporting companies aren't only being asked for this by regulators, they're being asked by their own customers, who are under the same mandatory reporting pressure and want primary data flowing down the chain rather than another layer of averages. If a customer is asking you for supplier-specific numbers, passing them an industry-average total doesn't hold up for long.

Outperforming the average is the reward once the data exists, it's what lets you tell a genuinely differentiated story, win the tender, or make the case to procurement. It's not the reason to start collecting it. The real drivers are proving a target, surviving assurance, and meeting what your own customers are starting to expect.

What this means for reporting companies right now

If you are reading your Scope 3 total and wondering why it isn't moving despite genuine supply chain effort, or why it does not seem to reflect what you know is happening on the ground with key suppliers, the number itself

isn't wrong. It's just reporting at the resolution you built it for.

The practical next question is not "should we move to supplier-specific data", eventually, most companies should, at least for their material categories. The more useful question is where first. Start with the categories carrying the most emissions or the most strategic weight, identify the suppliers you most need decision-useful data from, and build the request into your supplier engagement rather than treating it as a bolt-on data exercise. That is also, not coincidentally, where suppliers who have already invested in measuring and disclosing their own products and services footprint, through an Environmental Product Declaration or equivalent, start to become the easier, lower-friction data source in your inventory.

Industry averages got you a defensible number. Supplier-specific data is what turns that number into a decision-making tool. Both belong in a mature Scope 3 program; the question is only ever which one your next reporting cycle needs more of.

We work with reporting companies navigating exactly this transition, from average-based Scope 3 baselines to supplier-engaged, decision-useful inventories. If you are weighing where to prioritise supplier-specific data collection, get in touch.