Factor Boundary Checker
Every emission factor covers a certain amount of the supply chain — just the combustion, or everything upstream of it, or the whole lifecycle. That is its boundary, and the boundary decides which scope the factor belongs in. The number itself never tells you which one you have, and neither, most of the time, does the column header. Seven questions, about a minute, and this tells you whether your factor is where its boundary says it belongs.
Combustion is Scope 1, generation is Scope 2, and upstream fuel and grid losses are Scope 3 category 3. A lifecycle or biogenic figure belongs in no scope at all — it is a memo item, not a smaller Scope 2.
Seven questions, about a minute. An emission factor has a boundary — how much of the supply chain it covers — and the boundary decides which scope it belongs in. The number itself never tells you either, and neither, usually, does the column header.
- A well-to-wheel, lifecycle or cradle-to-gate figure is not a larger version of a scope 1 or scope 2 factor — it is a different quantity, and in our corpus rows of that kind carry no GHG Protocol scope at all. Booking one into scope 1 or scope 2 overstates that scope by the upstream portion and puts a number where the Protocol has a line for something else. Replace it with the direct row and book the upstream portion separately.
- Whether this factor carries biogenic CO₂, and where it is reported, has not been established. It matters most for fuels with a bio blend and for grid mixes with biomass generation, where the biogenic portion can be material and is easy to leave inside the scope total by default.
- The boundary has been taken from the factor name or inherited rather than traced to the source method document. That is the single most reliable way to be wrong here, and we have measured it in our own sourcing: a factor header frequently does not state its boundary at all, and where it does the wording is the publisher’s rather than the Protocol’s. One reading of the method note settles it permanently for that whole factor set.
What would change this verdict
- A factor set can change boundary between vintages without changing its name. A publisher that issued combustion-only figures and later moves to a well-to-wheel basis produces a step change in your trend that looks like performance and is not.
- Adding a bio blend to a fuel introduces a biogenic portion that was not there before, and it arrives inside the same factor family you were already using.
Coverage position — each test, where you stand, and the rule
| Test | Your position | The rule |
|---|---|---|
| What the factor is for | Purchased electricityDecides which boundaries exist for itmet | A fuel has a combustion and an upstream row; electricity has generation and losses |
| What the source calls it | Says well-to-wheel, total, lifecycle or cradle-to-gateBoundary declaredmet | The boundary is a property of the factor, not of the number |
| Where you booked it | Scope 2This boundary belongs in no scopeopen | The boundary decides the scope, and the corpus records it per row |
| Upstream booked separately | Not applicableNot applicablemet | Well-to-tank rows carry scope 3 category 3 in the corpus |
| Transmission and distribution losses | NoNot bookedopen | T&D loss rows carry scope 3 category 3, not scope 2 |
| Biogenic CO₂ | Not establishedNot establishedopen | Biogenic CO₂ is a memo item reported outside the scopes |
| How the boundary was established | Taken from the factor name or column headerAssumedopen | The boundary is in the method document, not in the header |
Why this verdict: The boundary this factor carries is not the boundary the scope expects. Two of the boundaries in our corpus carry no GHG Protocol scope at all — a lifecycle grid intensity and a biogenic CO₂ memo — which means booking either into scope 1 or scope 2 is not an error of degree. It puts a number where the Protocol has a line for something else, and the resulting total cannot be compared with anyone reporting correctly. A well-to-wheel figure in a direct scope has the same shape: it overstates that scope by exactly the upstream portion, and if the upstream is also reported in category 3 the energy is counted twice. The correction is to take the direct row for the direct scope and let the upstream row carry the upstream.
This page states no factor values and performs no arithmetic. It never adds an upstream factor to a combustion factor and never computes an uplift — it reports which boundary a row carries and whether that matches where you put it. The values themselves live in the factor browser, and the calculators are where they become a total.
A factor set can change boundary between vintages without changing its name, which produces a step change in your trend that looks like performance. We will email you when a set this checker applies to moves — not otherwise.
This checker applies the GHG Protocol scope definitions and the boundary each MasterBrain row records. It reads no inventory of yours and calculates nothing. It tells you whether a factor sits where its boundary says it belongs — not whether the value is current, whether the geography fits, or whether the source suits what you are reporting. Those are separate questions with their own checkers.
What this verdict means
Five outcomes, arranged by how much damage the mistake does and how likely it is to be caught. The ordering is deliberate: the worst one is not the biggest error, it is the one nobody ever queries.
Counted twice
A lifecycle or well-to-wheel factor already contains the upstream portion, and the upstream has been booked separately too. The same emissions are in the inventory in two places.
Boundary mismatched
The factor does not belong where it has been booked. A lifecycle intensity or a biogenic figure in Scope 1 or 2 is not a small error of degree — those carry no scope at all.
Upstream omitted
The factor is in the right place and only half the energy is in the inventory. Whatever emits before the fuel or electricity reaches you belongs in Scope 3 category 3, as its own line.
Boundary unstated
Nothing is wrong on the facts given, and the placement rests on an assumption. The boundary was read off a header or inherited rather than traced to the method.
Boundary matched
The boundary was established from the method document and the scope follows from it. A statement about placement only — not about whether the value is current or the geography fits.
Where each boundary belongs
Four boundary classes cover almost everything you will meet in a corporate inventory. The mapping is not a convention we have chosen; it follows from what each factor actually measures.
| Boundary | What it measures | Scope |
|---|---|---|
| Combustion / direct / tank-to-wheel | The fuel burning, at the point you burn it | Scope 1 |
| Generation | Producing the electricity or heat you bought | Scope 2 |
| Well-to-tank / upstream | Extraction, refining and delivery, before it reaches you | Scope 3, category 3 |
| Transmission & distribution losses | Electricity lost between the generator and your meter | Scope 3, category 3 |
| Lifecycle / well-to-wheel | All of the above, added together | None |
| Biogenic CO₂ | Carbon from biomass, reported as a memo item | None |
Those last two rows are the ones that surprise people, and they are the subject of their own section below. Everything above them is a normal accounting question with a right answer.
Read down your own energy types rather than down the boundary list — what matters in practice is which lines you should have for each thing you buy or burn.
| What you buy or burn | The direct line | The line most often missing | Also exists, and is not a scope |
|---|---|---|---|
| Fuel you burn yourself | Combustion — Scope 1 | Well-to-tank — Scope 3 cat 3 | Biogenic portion, if it is a bio blend |
| Purchased electricity | Generation — Scope 2 | T&D losses — Scope 3 cat 3 | Lifecycle intensity; biogenic portion of the mix |
| Purchased heat or steam | Generation — Scope 2 | Upstream fuel and network losses — Scope 3 cat 3 | Biogenic portion, where the source is biomass |
| Fuel a carrier burns for you | Combustion — Scope 3, the transport category | Well-to-tank — also Scope 3 | Well-to-wheel, which bundles both together |
The boundary is a property of how the factor was calculated, not of the number. Two factors for the same fuel, in the same units, differing by a factor of ten, can both be correct — because one is the combustion and the other is the whole lifecycle. Nothing about either figure reveals which is which.
The two failures, and why only one gets found
Boundary errors run in two opposite directions, and they are not equally likely to be discovered. That asymmetry is the single most useful thing on this page.
Upstream omitted — understated, and completely plausible
You take the combustion factor for your fuel, book it in Scope 1, and never book the upstream half anywhere. Or you take a grid factor, book it in Scope 2, and never book transmission and distribution losses in category 3.
This is the most common boundary failure and the least visible, because a combustion-only inventory is internally consistent. Every number in it is correct for what it claims to measure. The total is simply missing a component, and there is nothing in the figures that looks wrong — no implausible value, no broken ratio, no failed reconciliation. It gets caught, when it gets caught at all, by somebody asking a question about completeness rather than about arithmetic.
Counted twice — overstated, and unquestioned
You take a well-to-wheel or lifecycle factor, book it in Scope 1, and also book the upstream separately in category 3. The upstream is now in the inventory twice.
This one is worse, and not because the error is larger. It is worse because of the direction. An understated inventory eventually attracts a challenge from somebody who expected a bigger number. An overstated one reads as conservatism, and nobody objects to a company being cautious about its own emissions. It can sit in a reported figure for years, and the correction, when it comes, is a restatement downwards — which is a considerably more awkward conversation than a restatement upwards.
If you only have time to check one thing, check whether any factor described as total, well-to-wheel, lifecycle or cradle-to-gate sits alongside a separate upstream line for the same energy. That combination is always wrong, and it is the failure least likely to be flagged by anyone else.
The two boundaries that belong in no scope
A lifecycle grid intensity and a biogenic CO₂ figure are not scope figures. They are not larger or smaller versions of Scope 2 — they are different quantities that the GHG Protocol reports elsewhere, and in our own factor corpus they carry no scope classification at all.
A lifecycle grid intensity covers generation plus the upstream fuel supply chain plus, depending on the source, the construction and decommissioning of the generating assets. It is the right figure for comparing electricity systems and the wrong figure for a corporate inventory line, because the inventory splits those components across Scope 2 and Scope 3 and expects them reported separately.
Biogenic CO₂ — carbon released from biomass — is reported as a memo item outside the scopes, on the basis that the carbon was recently absorbed rather than released from geological storage. Folding it into a scope total inflates that scope and makes the figure incomparable with anyone reporting it correctly. This bites hardest on fuels with a bio blend and on grid mixes with significant biomass generation, where the biogenic portion is material and easy to leave inside the total by default.
The header is not the method
The boundary of a factor lives in the method document that accompanies the dataset, not in the factor’s name or its column header. We know this because we have measured it while building our own corpus: headers frequently state no boundary at all, and where they do, they use the publisher’s wording rather than the Protocol’s.
Open the dataset’s methodology annex and search for the words system boundary, scope of the factor, or the name of a lifecycle stage. It is usually one paragraph, and it settles the question for the entire factor set rather than for the one row you were checking. Record what it says next to the factor — the boundary is the property most often lost when a factor set is inherited by the next person.
The practical consequence is that “we used the DEFRA number” or “it came from the supplier” is not an answer to what boundary a factor carries. Both statements are compatible with any of the boundaries above, and both are the kind of provenance that gets passed down for years without anyone re-opening it.
Edge cases that change the answer
- A publisher can change basis between vintages without changing the name. A set that issued combustion-only figures and later moves to a well-to-wheel basis produces a step change in your trend that looks like performance and is not. The factor name is identical on both sides of it.
- An unlabelled figure is usually the direct one — but that is an inference. Where a publisher issues both a direct and an upstream table, the unlabelled figure is normally the direct one. That is a reasonable reading and it is not evidence, and it is worth confirming once rather than adopting permanently.
- Adding a bio blend introduces a biogenic portion. It arrives inside a factor family you were already using, without any change to your own process, and the biogenic split is often not surfaced in the headline figure.
- Market-based and location-based are a different axis entirely. Both are generation boundaries and both sit in Scope 2; choosing between them is an instrument question, not a boundary question, and it does not interact with anything on this page.
- A carrier’s fuel is your Scope 3, not your Scope 1. The boundary of the factor may be identical to the one you would use for your own vehicles. What changes is who burned it, and therefore which scope it lands in.
- Upstream leased assets and franchises can move the whole question. If an activity sits in Scope 1 for you under one consolidation approach and Scope 3 under another, the boundary of the factor has not changed — the boundary of your organisation has.
What this checker does not decide
It states no factor values and performs no arithmetic. It never adds an upstream factor to a combustion factor and never computes an uplift. It reports which boundary a row carries and whether that matches where you put it. The values live in the factor browser; the calculators are where they become a total.
It does not tell you whether your factor is current. A correctly placed factor can still be years out of date. That is the Emission Factor Vintage Checker.
It does not tell you whether the GWP basis is consistent. Mixing AR5 and AR6 across an inventory is a separate failure with its own test — the GWP Set Consistency Checker.
It does not tell you whether the geography or the source suits your activity. A correctly bounded, current factor can still be for the wrong country or the wrong process.
It does not adjudicate your organisational boundary. Which entities and activities are yours in the first place is a consolidation question, and it changes which scope an activity lands in without changing anything about the factor.
How we keep this current
The scope mapping on this page is not our convention — it follows the GHG Protocol’s own definitions, and it is the classification our factor corpus records against each row rather than one applied afterwards in prose. That is what lets this page diagnose rather than assert: when it says upstream fuel belongs in category 3, that is the classification carried by the rows themselves.
The checker stamps the date of the check into every result and every export you take from it. The re-check control in the result panel emails you when a factor set this page applies to changes its basis — which is the change most likely to alter your answer, and the one least likely to announce itself.
Frequently asked questions
Probably neither. The most likely explanation is that they carry different boundaries — one is the combustion only, the other includes the upstream supply chain or the full lifecycle. Both can be correct for what they claim to measure, and nothing about either number reveals which is which. Check what each source calls the figure, and if the name does not say, check the method document. Picking the larger one because it looks more complete is how a lifecycle figure ends up in Scope 1.
Almost certainly the upstream half. Fuel emits before you burn it — extraction, refining, delivery — and that portion belongs in Scope 3 category 3, as its own line. It is the most common boundary gap and the least visible, because a combustion-only inventory is internally consistent: every number in it is right for what it claims, and the total is simply missing a component. Most publishers that issue combustion factors issue the upstream table alongside them, so closing it is usually a matter of using data you already have access to rather than collecting anything new.
No. A lifecycle or well-to-wheel figure is not a more complete Scope 1 factor — it is a different quantity, and the inventory expects its components reported in different places. Putting it all in Scope 1 overstates Scope 1 by the upstream portion, and if you also report that upstream in category 3 the same emissions are counted twice. It also makes your Scope 1 incomparable with everyone else’s, which is the point of having the scopes at all.
Scope 3, category 3 — not Scope 2. Scope 2 covers the generation of the electricity you bought; the electricity lost between the generator and your meter was generated on your behalf but never reached you, and the Protocol puts it in the fuel- and energy-related activities category. It is a separate factor with its own value, and it is among the most commonly omitted lines in an otherwise complete Scope 2 position.
Because it bundles together things the inventory deliberately keeps apart. A lifecycle grid intensity covers generation, plus the upstream fuel supply chain, plus — depending on the source — the construction and decommissioning of the generating assets. Corporate reporting splits those across Scope 2 and Scope 3 and expects them separately. The lifecycle figure is the right number for comparing electricity systems and the wrong number for an inventory line, which is why factors of that kind carry no scope classification at all.
Report it separately, as a memo item outside the scopes. The reasoning is that the carbon was recently absorbed by the biomass rather than released from geological storage, so it is tracked but not added to a scope total. Folding it into Scope 1 or Scope 2 inflates that scope and makes your figure incomparable with anyone reporting correctly. It matters most for fuels with a bio blend and for grid mixes with significant biomass generation, where the biogenic portion can be material and is easy to leave inside the total by default.
Assume nothing, and check the method document — it is usually one paragraph and it settles the question for the whole factor set rather than for the row you were looking at. Where a publisher issues both a direct and an upstream table, an unlabelled figure is normally the direct one, but that is an inference rather than evidence, and it is exactly the sort of inference that gets inherited unexamined for years. A silent header is common and it is not the same as the boundary being combustion-only.
It is a strong candidate. A publisher can change the basis of a factor set between vintages — moving from combustion-only to well-to-wheel, for instance — without changing the factor’s name. The step change that produces looks like a change in performance and is a change in measurement. It is worth checking the method note for both vintages before attributing the movement to anything you did or did not do.
No — it is a different axis entirely. Both are generation boundaries and both sit in Scope 2. Choosing between them is a question about which instrument reflects the electricity you contracted for, not about how much of the supply chain the factor covers. Nothing on this page interacts with that choice, and getting the boundary right does not settle it.