Select an emission factor by its scope before its number

This guide is for inventory preparers and reviewers evaluating factor candidates. It supplies a selection workflow, not a factor library or a universal default. The applicable reporting programme and method govern the final choice.

Write the calculation need first

Specify the activity, reporting period, Scope 2 method and required gases.

Grid averages, contractual rates, life-cycle factors and avoided-emissions estimates serve different purposes. See GHG Protocol Scope 2 Guidance (2015), sections 6.5–6.11, for method-specific factor hierarchies. Choose for applicability, never merely for the lowest value.

This guide uses published guidance; proposed revisions are not applied as requirements.

Check six aspects of each candidate

1. Activity: fuel type, equipment, electricity supply or other activity represented, including blends or technology where relevant

2. Boundary: included emission sources and life-cycle stages

3. Geography and period: represented location, data year and applicability

4. Units: numerator, denominator and required conversions

5. Gases: CO2, individual gases or combined CO2e; check GWP basis

6. Method: source hierarchy and required contractual evidence

CO2 alone does not represent all gases. Do not reapply GWP to a combined CO2e factor. Retain gas-specific factors where required. Technical reference: EPA purchased-electricity guidance (December 2023), sections 1.1 and 2.1.

Check any programme-specific source rule

For BRSR Core, the Industry Standards Note addresses recognised factor sources and disclosure of the source used. For Indian grid electricity with measurable data, it specifies the latest applicable CEA-published grid factor. Source: part B, attribute 1. “Latest applicable” requires checking the publication and its intended use; this guide does not nominate a numeric factor or assume one year serves every purpose.

Recheck suitability before reusing a corporate-inventory factor for product or project calculations, or another Scope 2 method.

A hypothetical factor-selection review

Fictional teaching example, not a Nitium client case. A preparer has 12 MWh of electricity activity for one site and a defined generation-emissions calculation. Three candidate descriptions are reviewed:

• Candidate A: geography is unsupported for this calculation. Hold it.

• Candidate B: includes upstream stages outside this generation-only calculation. Hold it.

• Candidate C: passes these checks for this fictional exercise. Its invented value is 400 kg CO2e/MWh.

The example calculation is 12 MWh × 400 kg CO2e/MWh = 4,800 kg CO2e, or 4.8 tonnes CO2e. If the activity is stored as 12,000 kWh instead, convert to 12 MWh or use the equivalent 0.4 kg CO2e/kWh for this same invented factor. Do not multiply 12,000 directly by a per-MWh factor.

The number 400 is invented and must not be used as an actual reporting factor. Record each candidate’s disposition. Correct arithmetic cannot fix an unsuitable boundary.

Fictional calculation: 12 MWh × 400 kg CO2e/MWh = 4,800 kg CO2e = 4.8 tonnes CO2e. The same invented factor is 0.4 kg CO2e/kWh, so 12,000 kWh gives the same result. Neither value is a real reporting factor.

Keep a reproducible factor record

• Factor ID, publisher, document/dataset title and version

• Source URL and exact locator

• Publication date, data year, geography and applicability

• Original value and unit, gases and GWP basis

• Boundary and method conditions

• Selection rationale, reviewer and approval date

• Linked calculations and transformations

• Reuse or licence limitations and the permitted evidence reference

Link to the original source instead of circulating a copied paid or restricted factor table. Preserve the factor version used. Review new releases and apply the inventory’s change policy before revising historical calculations.

Before the factor enters the calculation

Have another reviewer verify selection, units, boundary and gas coverage. Reproduce the calculation and record unresolved questions and proxy limitations.

Our first-inventory checklist shows how activity and factor records fit together. Nitium's carbon footprint analysis service supports inventory calculations and documented assumptions within an agreed scope. Discuss a factor-selection question or email contact@nitium.in.

Reviewed 10 October 2026. Originally prepared 5 October 2026. This aid does not certify factor suitability, replace the applicable methodology or provide independent assurance. All example factors are fictional.