Standards and reporting
GHG conversion factors
GHG conversion factors turn recorded activities into estimated emissions, provided the activity, unit, year and accounting boundary match the selected factor.
What do the government factors actually do?
The government publication supports activity-based calculation of Scope 1, 2 and 3 emissions separately, rather than deciding which disclosures an organisation owes.
Module 01 / 04
Activity
Start with the measured quantity, such as electricity purchased or distance travelled.
Module 02 / 04
Factor
Select the row that describes the activity and its measurement unit.
Module 03 / 04
Classification
Assign the result to its appropriate inventory scope and category.
Module 04 / 04
Disclosure
Apply the requirements of the report being prepared.
Read the detailed guidance and evidence
The Corporate Standard provides the accounting framework, while the factor workbook supplies calculation inputs.
Our standards overview helps separate the reporting basis from the calculation method.
Which 2026 file should you download?
Use the full set for its instructions and the corrected flat file where automatic processing is appropriate.
| Resource | Use | Check |
|---|---|---|
| Full set | Human review of worksheets, definitions and factors | Read Introduction, relevant worksheet guidance and What’s new |
| Flat file | Automated processing | Retain the July 2026 corrected version and a stable row identifier |
| Methodology | Understanding derivation and limitations | Read the chapter for the activity being calculated |
| Major changes | Interpreting movements between publications | Identify changes before comparing annual results |
Which factor year matches your reporting period?
Use the annual set for activity falling entirely or mostly within its calendar year under methodology paragraph 1.10.
Module 01 / 04
Activity dates
Record when the consumption or journey occurred.
Module 02 / 04
Annual majority
Identify the calendar year containing most of the reporting activity period.
Module 03 / 04
Publication
Retain the matching annual factor publication.
Module 04 / 04
Filing date
Do not substitute the year in which the report is filed.
Read the detailed guidance and evidence
A fictional April 2026 to March 2027 period falls mostly within calendar 2026, so the annual-set rule points to 2026 rather than the filing year.
An exactly balanced or unusual period deserves a documented judgement rather than a fabricated automatic answer.
How do you stop unit errors?
Write the activity and factor units beside each other before multiplying, using the definitions in the relevant workbook worksheet.
| Activity record | Factor denominator | Preparation check |
|---|---|---|
| Electricity in MWh | kWh | Convert MWh to kWh before applying a per-kWh factor |
| Fuel in litres | litres or kWh | Choose a factor matching the available fuel evidence |
| Travel distance | vehicle-km or passenger-km | Do not exchange vehicle and passenger units |
| Freight activity | tonne-km | Retain both the mass and distance basis |
Which parts of an emissions factor belong together?
Keep generation, transmission losses and upstream fuel emissions distinct, following DESNZ paragraph 3.9 and the applicable inventory boundary.
Module 01 / 04
Generation
Purchased electricity generation is the Scope 2 component.
Module 02 / 04
Grid losses
Transmission and distribution losses are separately classified as Scope 3.
Module 03 / 04
Upstream
Well-to-tank factors address upstream fuel-chain emissions.
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No duplication
Do not add an aggregate and its components to the same total.
Read the detailed guidance and evidence
The Scope 2 guide explains the purchased-energy methods, while the Scope 3 guide addresses value-chain categories.
A factor labelled consumed electricity does not make every component Scope 2.
What does a worked conversion look like?
This fictional 12 MWh electricity example uses the real Table 9 generation factor without adding upstream or grid-loss components.
| Step | Value | Interpretation |
|---|---|---|
| Recorded activity | 12 MWh in calendar 2026 | Fictional UK purchased grid electricity |
| Normalise unit | 12 × 1,000 = 12,000 kWh | Matches the factor denominator |
| Apply factor | 12,000 × 0.13096 = 1,571.52 kgCO₂e | 2026 generation factor in kgCO₂e/kWh |
| Present tonnes | 1,571.52 ÷ 1,000 = 1.57152 tCO₂e | Generation emissions only |
Why does the exact file version matter?
The 31 July correction changed erroneous zeros to blanks in parts of the flat file, while the June full set was unchanged.
Module 01 / 04
Source file
Save the actual workbook or flat file used.
Module 02 / 04
Release note
Record its publication and correction status.
Module 03 / 04
Missing values
Keep unavailable values distinct from genuine zero factors.
Module 04 / 04
Recalculation
Identify outputs affected by a corrected input.
Read the detailed guidance and evidence
The affected flat-file areas include certain well-to-tank car factors and hotel stays, according to the government correction notice.
Treating an unavailable factor as zero would silently remove an estimated emissions contribution rather than resolve the evidence gap.
Does a lower factor prove an operational saving?
No, because the 2026 major changes report and methodology identify changes to both data and methods.
| Possible cause | Question to investigate | Evidence |
|---|---|---|
| Activity change | Was less energy actually consumed? | Comparable quantities and boundary |
| Grid change | Did the electricity generation mix change? | Annual methodology and data |
| Method change | Did factor derivation change? | Methodology break and revision notes |
| Boundary change | Were sites or activities added or removed? | Inventory and consolidation record |
What should you do when activity data are missing?
Record the gap and chosen estimation method rather than quietly replacing missing evidence with zero, with methods disclosed as directed by the publication.
Module 01 / 04
Identify
Name the site, period and activity with missing evidence.
Module 02 / 04
Estimate
Document an appropriate estimation basis and its limitations.
Module 03 / 04
Separate
Keep estimated records distinguishable from measured inputs.
Module 04 / 04
Review
Assign an owner and revisit the estimate when records arrive.
Read the detailed guidance and evidence
The publication distinguishes these activity-based factors from Defra spend-based multipliers, which may support an initial supply-chain assessment where activity data are insufficient.
The Scope 3 calculation guidance addresses category-specific methods rather than a universal substitute for missing activity data.
What belongs in a factor evidence register?
Keep the selected source row and calculation alongside the activity record so another preparer can reproduce it.
| Record | Fields | Purpose |
|---|---|---|
| Activity | Entity, site, period, quantity and unit | Establish what was measured |
| Factor | Publication, file version, worksheet, row and value | Locate the calculation input |
| Boundary | Scope, category, geography and component | Prevent incompatible aggregation |
| Review | Estimate, correction, reviewer and unresolved issue | Explain decisions and changes |
What should a platform or consultant demonstrate?
Ask for the worked example to be reproduced with an exportable calculation trail before relying on an aggregated dashboard.
Module 01 / 04
Import
Preserve activity units and distinguish blanks from zeros.
Module 02 / 04
Factor library
Show annual versions and exact selected rows.
Module 03 / 04
Correction
Replace an input while retaining its history.
Module 04 / 04
Export
Provide activity, factor, calculation and review records.
Read the detailed guidance and evidence
Use the carbon software buying guide and carbon consultancy guide to turn unresolved calculation questions into a defined brief.
For SECR, the methodology disclosure still needs a clear explanation even when software performs the arithmetic.
Which mistakes should a reviewer look for?
Check the input relationships as well as the arithmetic, with the methodology available beside the workbook.
| Risk | Review test |
|---|---|
| Wrong year | Compare the activity period with the annual-set rule |
| Wrong denominator | Cancel units explicitly in a sample calculation |
| Double counting | Identify aggregate factors and their components |
| False improvement claim | Separate activity, boundary, data and methodology changes |
How do factors support a reporting handover?
The useful deliverable connects the published result to its underlying activity and documented judgements, rather than delivering a number alone.
Module 01 / 04
Report
Name the reporting output and its boundary.
Module 02 / 04
Working
Retain the detailed calculation and selected factors.
Module 03 / 04
Explanation
Describe estimates and comparability limitations.
Module 04 / 04
Ownership
Identify who can answer outstanding evidence questions.
Read the detailed guidance and evidence
The Environmental Reporting Guidelines explain the wider reporting context.
Use the SECR report template to connect these calculation records to a report outline.
How should you prepare a factor calculation?
This editorial nine-stage sequence organises the evidence and review without creating a separate reporting obligation.
- 101
Name the output
Identify the reporting basis and required emissions boundary. - 202
Map the activity
List included sources, sites and reporting dates. - 303
Reconcile records
Resolve missing bills, duplicates and estimated quantities. - 404
Choose the annual set
Apply the activity-year rule and document unusual periods. - 505
Select the row
Check geography, activity, unit and component. - 606
Calculate
Retain unrounded working values and convert output units. - 707
Test the aggregation
Keep scopes and upstream components separate. - 808
Review changes
Explain corrections, assumptions and comparability limitations. - 909
Retain the evidence
Save the source file, calculation and approved disclosure.
Which annual set matches your dates?
Use the activity-period check as a preparation aid, with unusual periods reviewed against the methodology.
Which factor set applies · by the activity-data year
A check of the factor-year rule only.
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Can you download a working outline?
This original editable outline supports preparation and review and is not a government-approved form.
| Use | Review |
|---|---|
| Adapt | Replace example fields with the actual reporting boundary and records |
| Check | Review every applicable requirement and unresolved issue before reporting |
Frequently asked
Questions people ask
Are these still called Defra conversion factors?
The older name is widely used, but the 2026 company-reporting publication is issued by DESNZ.
Should I use the year I file the report?
Match the annual set to activity falling entirely or mostly in that calendar year, rather than automatically using the filing year.
Is the flat file the same as the full set?
It is the automatic-processing format and should be used with the guidance and exact release status of the full publication.
Is a blank factor a zero?
No, because an unavailable factor must not be interpreted as a measured zero-emissions value.
Are electricity grid losses Scope 2?
The DESNZ methodology distinguishes generation as Scope 2 from transmission and distribution losses as Scope 3.
Does the 2026 factor fall prove our company reduced emissions?
No, because reported changes can reflect activity, boundaries, underlying data and methodology as well as operational action.
Sources
Primary sources
Primary provisions and official owner guidance checked on 26 October 2026; historical and draft resources are labelled in the guide.
- DESNZ2026 conversion factors: files and July correction
- DESNZ2026 methodology: paragraphs 1.10, 3.8–3.9 and Table 9
- UK GovernmentEnvironmental Reporting Guidelines
- DESNZAnnual conversion factor collection
- DESNZ2025 conversion factor publication
- DESNZ2026 major changes report
- GHG ProtocolCorporate Accounting and Reporting Standard
- GHG ProtocolScope 2 Guidance
- GHG ProtocolCorporate Value Chain Standard
- GHG ProtocolScope 3 Technical Calculation Guidance
- legislation.gov.ukSECR methodologies: paragraph 20F
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