Where factors come from
Factors come from the reference library. Every factor carries a reference to its source document and a licence, and is marked verified only when a person has checked it against that document, never by the software. Each reporting year is calculated with one pinned library release, so a new release never changes past years silently. See Reference library.
Factors are never typed in from memory. Where no factor exists for a gas that a source needs, the calculation reports a finding instead of inventing a value.
Your own emission factors
Setup → Your emission factors holds factors your organisation supplies: a fuel analysis, a supplier’s grid factor, a national factor the library lacks. Methodology owners and client admins add them; everyone else can read them.
- Precedence. A factor of your own beats the reference library for every source it matches: one set on a source first, then one set on an asset, then one for the whole organisation. Leave Applies to fields empty to match any value, or narrow it by fuel type, category, grid region and so on. A factor for the whole organisation with no attributes applies to every source that needs that role and gas, so narrow it.
- Country. Choose a country to limit the factor to that country’s assets. National grid factor fills in the grid factor role, CO₂ and t/MWh for a country whose grid factor the reference library does not have; a factor for one country outranks an otherwise equal one for every country.
- Units. The unit list shows the units the reference library uses for the chosen role, so the calculation can convert the value.
- Citation. Reference and Licence are required: name the document and who may use the value.
- Verification. Mark verified records your name and the date after you have checked the value against its reference. Until then results using it carry the unverified-factor warning. Changing any value clears the verification; editing only the note does not.
- Preview. Preview runs a dry-run calculation of one reporting year with the change and shows the CO₂e difference in total and per asset. Nothing is saved.
- Recalculation and locked months. Saving or deleting recalculates the months the factor covers. A change that would alter a locked month is refused; the preview lists those months. Reopen them for a restatement, or start the factor after them. See Reporting periods.
- Plan. Adding and editing your own factors is part of the Pilot, Professional and Enterprise plans. On Essentials existing factors stay readable and can be deleted.
The unverified-factor warning
The amber badge Includes unverified factors (x%) on the dashboards shows the share of the emissions in view that used at least one factor not yet verified. The Unverified factors tile on Data quality shows the same share. The audit export lists, for every result, whether each factor used is verified.
Energy basis: HHV and LHV
Combustion factors are published per unit of energy, either on a gross (higher heating value, HHV) or a net (lower heating value, LHV) basis. Each factor in the library states its basis.
- EmitLedger applies a factor only to energy on the same basis. It never converts between HHV and LHV.
- For gaseous fuel, the energy comes from the gas composition: enter LHV (MJ/Sm³) and HHV (MJ/Sm³) on the sample when the laboratory report gives them. See Gas compositions.
- If a factor needs HHV energy and the composition has no HHV, the calculation reports a finding for the gases that need it. CO₂ from the carbon mass balance is not affected.
- Liquid fuels use the calorific value for the factor’s basis from the library.
Factors published only as CO₂e
Some publishers give factors only as CO₂-equivalent, computed with a GWP set they state. EmitLedger uses such a factor as published:
- the result is stored as CO₂e, not split into CO₂, CH₄ and N₂O;
- changing the GWP set filter does not change that part of the total, because the publisher already applied its own GWP set;
- the calculation records which GWP set the publisher used, and warns when it differs from your organisation’s default GWP set.
Grid regions and industry segments
- Location-based Scope 2 uses the grid factor of the asset’s country, or of its Grid region when the asset has one and the library has a factor for it. When a regional factor cannot be used, the calculation falls back to the country factor and warns.
- Some factors apply only to one Industry segment. They are used only when the asset’s segment is set.
Both fields are on the asset’s Details tab. See Asset setup.