Scope 2 Electricity Emissions: Methodology and Grid Emission Factors

Step-by-step method for converting metered electricity consumption into a defensible Scope 2 inventory under the GHG Protocol Corporate Standard with mandatory dual reporting (location-based + market-based per Scope 2 §6.3), a 50-jurisdiction grid-factor reference table backed by live MasterBrain shortcodes, an EAC instrument decision matrix covering REGOs, GOs, RECs, I-RECs and PPAs, residual mix treatment for AIB European and EPA eGRID jurisdictions, the Scope 3 Cat 3 T&D companion calculation, and a forward-looking section on hourly carbon-free energy. Aligned to the GHG Protocol Corporate Standard, GHG Protocol Scope 2 Guidance (2015), UK DEFRA 2025, Ember Yearly Electricity 2025, and EPA eGRID 2023.

A methodology page is the execution layer — it takes the boundary definitions from the glossary, the certificate definitions from the EAC reference, and the raw factor dataset from the data layer, and tells you exactly how to translate metered electricity consumption into a defensible Scope 2 inventory. Unlike Scope 1 (where variant misselection dominates), Scope 2’s primary editorial challenge is the dual-method requirement — every reporter holding contractual instruments must publish two parallel inventory totals, and the most common production failure is a market-based “zero” that is not the same kind of zero across frameworks (a bundled REGO is not a contracted PPA, and SBTi reviewers increasingly know the difference). Jump to the decision tree, the 50-jurisdiction factor table, or open the Scope 2 Electricity Calculator.

Why Scope 2 Is Structurally Different from Scope 1

Scope 1 is a closed system. Fuel goes in, combustion happens inside the inventory boundary, CO₂ comes out. The reporter owns the meter, the fuel, the asset, and the emission. The factor library is a published lookup against a small set of fuel chemistries. The accounting question is “did you pick the right factor for the right fuel” — most production failures live in variant-selection error, not in any structural ambiguity about the inventory itself.

Scope 2 inverts almost every one of those properties. Electricity arrives at the meter from a grid the reporter does not own, generated by a portfolio of assets the reporter does not control, with a per-kWh emission profile that varies by hour, by season, and by year. The reporter does not own the emission — they own the consumption, and the GHG Protocol Scope 2 Guidance (2015 amendment to the Corporate Standard) defines two parallel methodologies for converting that consumption into a reportable inventory:

• Location-based (LB) — the reporter’s electricity consumption is multiplied by the average emission intensity of the grid that physically delivered it. The factor is published by a national or regional grid authority (DEFRA for the UK, IEA for most other sovereign nations, EPA eGRID for the US). The accounting question reduces to a single look-up plus a multiplication.
• Market-based (MB) — the reporter’s electricity consumption is multiplied by the emission profile they have contracted for, recognised through energy attribute certificates (REGOs, GOs, RECs, I-RECs), power purchase agreements (PPAs), or supplier-specific tariff disclosures. The portion of consumption not covered by any qualifying contract uses a “residual mix” factor — the average intensity of the grid after removing the generation already claimed by other reporters’ instruments.

The two methods produce different numbers for any reporter holding renewable instruments. The Scope 2 Guidance §6.3 requires that both numbers be disclosed when market-based instruments are held — neither suppresses the other, and “we report market-based only” is non-compliant. This dual-reporting invariant is the defining structural feature of Scope 2 accounting and is enforced in every audit-grade calculation engine, including our own.

Regulatory Matrix — What Each Framework Requires

Before choosing a method, confirm what each framework you report to actually requires. The five most common Scope 2 disclosure regimes diverge in subtle but material ways, particularly on whether market-based is acceptable as a sole disclosure (it almost never is) and on the GWP basis expected for any per-gas reconstruction (rare for Scope 2 — grid factors are pre-aggregated CO₂e at the publisher’s basis, but the basis still must be disclosed).

Three patterns emerge. First, location-based is required by every framework — even the most market-friendly regime never lets the reporter delete it. Second, market-based scrutiny is rising — what passed CDP review in 2018 (a Scope 2 zero from bundled REGOs purchased on the secondary market) is increasingly questioned by SBTi reviewers in 2026. Third, regulatory disclosure and target-tracking diverge: SBTi’s emerging position is that a bundled REGO can satisfy CDP and CSRD compliance but does not move the dial on a science-based target without additional additionality evidence. The methodology choice cascades from these distinctions.

Residual Mix — The Most-Skipped Section in Scope 2 Reporting

Residual mix is the emission factor for the portion of grid electricity not claimed by any contractual instrument. Conceptually: take the published grid average, subtract the generation associated with all the renewable EACs already retired by other reporters, and what remains is dirtier than the grid average — because the renewables have been “claimed”. A reporter with 50% EAC coverage who uses the published grid average for the unmatched 50% double-counts the renewable generation on their unmatched portion. The residual mix corrects this.

The mathematics of why residual mix exceeds grid average: in any jurisdiction with significant renewable generation, the published grid factor is the volume-weighted average across the full generation portfolio (renewable + fossil + nuclear). When any reporter retires a REGO/GO/REC for, say, 1 MWh of wind generation, that 1 MWh of zero-emission generation is now “owned” by them. For everyone else on the grid still using the grid-average factor, that wind MWh has effectively been removed from their share — the residual generation pool is dirtier. The residual mix factor reconstructs this dirtier pool as a published number.

Three jurisdictions to know:

• AIB European Residual Mixes — published annually by the Association of Issuing Bodies, covering the EU-27 plus UK, Norway, Switzerland, Iceland. The 2024 publication shows residual mix factors for member states ranging from approximately 0.3 to 0.6 kg CO₂e/kWh — well above the published grid averages because European EAC retirement volumes are substantial. The UK 2024 residual mix is approximately 0.488 kg CO₂e/kWh — over 2.7× the LB grid factor of 0.131 kg CO₂e/kWh.
• EPA eGRID residual mix — published as part of the eGRID release, covering the 26 NERC subregions. Used in market-based Scope 2 reporting for US sites with declared instruments. eGRID also publishes “non-baseload” rates which are a different decision tool used for marginal-emission analysis, not for Scope 2 residual.
• Outside AIB and EPA territories — no published residual mix exists for most non-European, non-US jurisdictions. Industry practice is to use the location-based grid factor as a residual proxy with explicit audit flag, or apply a conservative untraced premium (typically 1.10× to 1.20× the grid factor). The Scope 2 Electricity Calculator applies a 1.15× factor by default for unsupported jurisdictions and surfaces an audit warning to that effect — which is a defensible conservative position but should be replaced with a published residual mix where available.

EAC Decision Matrix — REGOs, GOs, RECs, I-RECs, PPAs

The table below is the production reference for which energy attribute certificates count as what under which framework. Six rows cover the dominant instrument types globally; the columns capture framework recognition, the GHG Protocol Quality Criteria position, additionality, residual mix treatment, and audit risk.

The structural pattern: bundled REGO/GO/REC has the lowest cost per MWh and the lowest additionality credit; contracted PPAs have the highest cost and the highest credit. SBTi’s emerging position increasingly differentiates between these — what counts toward CDP scoring or CSRD compliance does not necessarily count toward science-based target progress without project-level additionality evidence. The methodology consequence: a Scope 2 zero achieved through bundled REGOs is a different disclosure from a Scope 2 zero achieved through a contracted VPPA, even though the calculation arithmetic is identical. Reporters should make the instrument basis visible in their disclosure narrative.

The Calculation — Step by Step

The two methods share an identical mathematical structure but apply different factors to different portions of the consumption.

Two subtleties matter at audit. First, when an EAC instrument is held but no supplier factor is disclosed, the matched portion is treated as zero-emission per REGO/GO/REC convention — that is the entire point of the instrument. Second, EF_residual ≠ EF_grid in any jurisdiction with material EAC retirement; using the grid average for the unmatched portion double-counts the renewable generation already claimed by other reporters and is a methodological error specifically called out in CSRD ESRS E1-6.

Country and Subregion Factor Reference — 40 Sovereigns + 10 US eGRID Subregions

The full MasterBrain v2025.6 grid registry, rendered live via the — shortcode. Every cell auto-updates on the next DEFRA / IEA / EPA annual release without manual edits to this page. Sources: DEFRA 2025 (UK), Ember Yearly Electricity 2025 (most non-US sovereigns), EPA eGRID 2023 (US national + subregions). Values are gross-generation basis — T&D losses are not pre-baked; treat them as a Scope 3 Cat 3 companion per §7.

The structural span: from 0.028 kg CO₂e/kWh in Norway (~99% hydropower) to 0.699 in South Africa (coal-dominant) — over a 25× range across the MasterBrain set. Within the United States, the eGRID2023 subregion span is narrower but still material: 0.110 (Upstate NY hydro+nuclear) versus 0.566 (SERC Midwest, coal 59%) — a 5× spread that swamps the precision improvement from any other methodology choice. Always use the eGRID subregion factor in preference to the national average for US sites with subregion-traceable supply — the geography is doing more work than the methodology in any US Scope 2 inventory.

Scope 3 Cat 3 T&D Losses — The Companion Calculation

Approximately 5–10% of every kWh generated is lost between the power station and the meter — heat dissipation in transmission lines, transformer losses, distribution-network resistance. Those losses are physical generation that the reporter caused but does not consume, and the GHG Protocol Scope 3 Standard Category 3 (Fuel- and Energy-Related Activities, “FERA”) allocates them to the buyer as a separate inventory line. The Scope 3 Cat 3 T&D companion is mandatory under the Scope 3 Standard, increasingly expected under CSRD ESRS E1 value-chain disclosure, and routinely required by CDP for full points. The full country-by-country loss factors, the two arithmetic shapes, and the audit checklist are documented in our T&D losses methodology, with the 40-country implementation available in the T&D Losses Calculator.

Two methodology fixed points. First, T&D companion is computed against the location-based grid factor only — physical losses occur on the grid regardless of contractual instruments held. A reporter with 100% PPA coverage still has T&D losses on the physical grid, and they still belong in Scope 3 Cat 3. Second, the loss-percentage-to-factor conversion uses the “delivered kWh” denominator: per kWh consumed at the meter, the upstream grid generated kWh ÷ (1 − loss%) — and the loss is the difference. The (1 − loss%) denominator is the small-but-easy mistake that converts a 5% loss into a 5% headline rather than the correct ~5.3%.

For a UK reporter consuming 2,500,000 kWh: T&D factor = 0.177 × 0.083 / 0.917 = 0.01602 kg CO₂e/kWh; T&D companion = 2,500,000 × 0.01602 = 40,054 kg = 40.05 tCO₂e. As a share of the LB Scope 2 total (442.50 tCO₂e at 0.177 grid factor): 9.05%. For most reporters T&D sits in the 5–10% range relative to LB Scope 2 — material enough that omission is visible to any audit reviewer doing a back-of-envelope check.

Worked Examples — Cross-Verified to the Calculator

Three audit-record snapshots at this page’s review date (2026-05-09). Hardcoded values throughout per Editorial Standards §9b. To replicate any example, open the Scope 2 Electricity Calculator and enter the inputs documented in each example header — the calculator’s hash output will match the values shown here as long as MasterBrain v2025.6 is the active version.

Self-Generated Renewables — When Does It Reduce Scope 2?

On-site solar PV, on-site wind, and on-site CHP that generates electricity raise a Scope 2 boundary question: when does self-generated electricity reduce Scope 2, and when does it require an EAC retirement to claim the reduction?

The GHG Protocol position (Scope 2 Guidance §7.5 plus the Corporate Standard’s general control rules):

• Self-generated electricity consumed on-site, retained by the generator — never enters Scope 2 in the first place. There is no purchase, no grid import, no inventory line. The reporter does not need to retire EACs against this consumption because there is nothing to “match” — they directly own and consume the generation.
• Self-generated electricity exported to the grid — sold; the buyer’s EAC retirement (or the residual mix consequence) determines whose inventory it appears in. The seller does not get to keep the EAC and the export simultaneously; if EACs are sold along with the energy, they are no longer the seller’s to claim.
• Self-generated electricity consumed on-site with EACs sold separately to a third party — this is the trap. If the reporter has sold the EACs (REGOs/GOs) issued against their on-site generation to another organisation, that other organisation has the renewable claim. The original generator must use the residual mix factor for their on-site consumption, not zero — they kept the energy but not the attribute.
• Self-generated CHP electricity — the electricity portion is treated as above; the heat portion is Scope 1 (combustion of the input fuel) and the methodology overlaps with the natural gas combustion methodology for the fuel input.

The audit question for any organisation claiming Scope 2 reduction from on-site renewables: “did you retain the EACs?” If yes, the on-site consumption is genuinely zero-Scope-2. If no, the on-site consumption uses the residual mix and the reporter has a sold-EAC accounting line elsewhere. Mixing the two — claiming both the on-site reduction and the EAC sale revenue — is a double-count flagged by every reasonable-assurance audit.

Forward-Looking — Hourly Carbon-Free Energy and Granular Certificates

The current Scope 2 methodology operates on annualised matching: a reporter consuming 2.5 GWh in a year and retiring 2.5 GWh of REGOs declares 100% MB coverage even when their actual hourly consumption profile does not match the hourly generation profile of the wind farm whose REGOs they retired. The 100% annual match might in reality reflect a wind farm that overproduces at night when the office is closed and underproduces on still summer afternoons when the office is at peak demand — a structural mismatch that annualised matching cannot see.

Hourly carbon-free energy (CFE) accounting, sometimes called 24/7 CFE, refines this. Instead of matching annual MWh totals, the reporter matches each hour’s consumption against each hour’s generation — and the “match score” is the fraction of hours where renewable generation covered consumption. Google’s published 24/7 CFE methodology, the EnergyTag Standard (released 2022, updated since), and emerging EU Granular Guarantees of Origin frameworks are the production references.

Two reasons to track this even if your current disclosure does not require it:

• SBTi review trajectory. SBTi reviewers since approximately 2024 have begun referencing hourly matching in target validation discussions for organisations claiming material renewable coverage. The current standard does not require hourly matching, but a reporter with strong hourly metrics has a stronger story than one with annualised metrics alone. The trajectory is toward hourly being the gold standard within 5–7 years.
• EU regulatory pipeline. The European Commission’s 2023 proposal for granular Guarantees of Origin would create an hourly-resolution EAC market across the EU-27, retiring against hourly consumption profiles. The proposal is not yet binding regulation but reporters with European footprint are already preparing for it; a 2026 inventory built on annualised assumptions may face adjustment when the granular regime is enacted.

The methodology consequence today: hourly matching is not yet shortcoded into the MasterBrain or the calculator (no [gc_cfe_match] shortcode exists; flagged for future migration). For organisations with material PPA coverage and an interest in 24/7 CFE, the practical path is to compute hourly match externally (typically using meter-data-aggregator hourly profiles plus PPA generation telemetry) and disclose the match score alongside the annualised MB total. The annualised MB remains the headline disclosure under current frameworks; the hourly score is the forward-looking complement.

Standards Alignment

Six standards govern Scope 2 electricity accounting. Each layer supplies a different input to the same audit-grade output.

What the Calculator Handles vs What You Decide

The Scope 2 Electricity Calculator automates the mechanical steps. This methodology page covers the upstream decisions the calculator cannot make for you.

Ready to compute? Open the Scope 2 Electricity Calculator →

Audit Checklist — Scope 2 Reasonable-Assurance Pre-Flight

Eight items, in order. Run this list before submitting any Scope 2 disclosure for reasonable-assurance review under ISO 14064-1 or equivalent. Each item maps to a specific failure mode that auditors look for first.

1. 01
   Grid factor freshness. Confirm the grid factor used is the most recently published version for the inventory year being reported. UK reporters: DEFRA publishes annually in June — a 2026 inventory should use DEFRA 2025 (the factor for the 2025 inventory year as published 2025/06). Stale-factor risk is high — see Example A’s 17.0% sensitivity. The MasterBrain v2025.6 grid registry timestamps every factor with its source publication; replicate that traceability in your own audit trail.
2. 02
   Dual-method completeness (Scope 2 §6.3). If any contractual instruments are held — even one bundled REGO — both LB and MB totals must appear in the disclosure. Suppressing LB on the basis that “we report market-based” is non-compliant. Verify the disclosure pair is intact.
3. 03
   Residual mix factor citation. For any MB calculation with less than 100% EAC coverage, the residual mix factor used on the unmatched portion must be disclosed with provenance. AIB-published value, EPA eGRID residual, or untraced-premium approximation — name the source. CSRD ESRS E1-6 specifically requires this.
4. 04
   EAC retirement evidence. Every claimed REGO / GO / REC / I-REC must trace to a retirement statement issued by the relevant registry (Ofgem, AIB issuing body, US REC tracking system, I-REC Standard registry). Retirement against the reporting year — not subsequent or prior years. Sample at least 5 instruments per material EAC class for evidence retention.
5. 05
   SBTi additionality posture. If reporting against an SBTi target, the target-progress commentary must address the additionality posture of bundled instruments. Bundled REGO/GO from existing assets are valid CDP/CSRD MB inputs but increasingly questioned for SBTi target progress. Pre-empt the question with explicit posture disclosure.
6. 06
   Scope 3 Cat 3 T&D inclusion. T&D losses are required under GHG Protocol Scope 3 Standard Cat 3 (FERA, T&D sub-component). Computed against LB only, on a separate inventory line — never aggregated into Scope 2. Verify the line is present and correctly classified.
7. 07
   Multi-site portfolio invariant. When any site uses MB, the portfolio MB total must include all sites — sites without MB inputs carry their LB figure as the conservative default per §6.3. Verify the portfolio MB total is the correct sum (not just the sum of MB-declaring sites). The calculator engine §8 enforces this; check it has not been bypassed.
8. 08
   Self-generation EAC posture. For any on-site solar / wind / CHP claim of Scope 2 reduction, confirm whether the EACs were retained or sold. Retained → genuine zero-Scope-2 for that consumption. Sold → residual mix factor applies on the on-site consumption. Double-counting EAC sales revenue and on-site Scope 2 reduction is the highest-risk failure mode in self-generation disclosures.

Methodology Metadata — for GHG Inventory Documentation

Copy verbatim into your GHG inventory methodology statement for ISO 14064-1 transparency compliance. Adjust the method, jurisdiction, and instrument lines to match your inventory choices.

Frequently Asked Questions

Calculator

Apply this methodology with audit-grade output, dual-method (LB + MB) display, multi-site portfolio mode, automatic Scope 3 Cat 3 T&D companion, full 50-jurisdiction grid coverage, EAC instrument tagging, residual mix application, and JSON + CSV export with full provenance: Open the Scope 2 Electricity Calculator →

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