GHG Protocol · carbon accounting standards
GHG Protocol: the standards behind every carbon footprint
The GHG Protocol is the set of accounting standards that defines Scopes 1, 2 and 3 and how an organisation builds an emissions inventory.
It is not one document: the Corporate Standard, the Scope 2 Guidance and the Scope 3 Standard each say different things about what must be reported.
This page separates them, shows how UK SRS S2 uses them, and sets out the revision now planned with ISO.
The documents
Three documents, three different requirements
People say “the GHG Protocol” as if it were one rulebook.
For a company there are three core documents, and they disagree about what is required, especially on Scope 3.
| Document | Edition | What it requires | Scope 3 |
|---|---|---|---|
| Corporate Accounting and Reporting Standard | Revised edition, 2004; gases amended 2013 | A minimum of Scope 1 and Scope 2 (Ch. 9) | An “optional reporting category” (Ch. 4) |
| Scope 2 Guidance | 2015, an amendment to the Corporate Standard | Location-based and market-based Scope 2 where contractual instruments exist | Not covered |
| Corporate Value Chain (Scope 3) Standard | 2011 | Account for all Scope 3 emissions it defines; disclose and justify exclusions (§6.2) | All 15 categories (Table 5.4) |
The Corporate Standard is not frozen in its 2004 text.
The GHG Protocol’s own landing page says it now covers seven gases, adding nitrogen trifluoride (NF3), and that it was updated in 2015 with the Scope 2 Guidance.
The Scope 3 calculation guidance is a companion document: it explains calculation methods for each category, and refers back to the Scope 3 Standard for the requirements.
Scope 2
Location-based, market-based, and not gross and net
The Scope 2 Guidance introduced two methods for purchased electricity, heat, steam and cooling.
The location-based method applies average grid factors; the market-based method uses contractual instruments.
Companies with operations in markets that offer such instruments are asked to report both.
The Guidance warns that the two totals should not be read as gross and net, because a net figure implies offsets have been applied.
It also says the market-based method includes fossil and mixed-resource instruments, so it is not a renewables-only method.
UK SRS S2 departs from the Guidance here: it requires location-based Scope 2 and permits market-based figures, so a company can comply with one location-based number.
How the market-based figure is built from UK data is on our market-based Scope 2 page.
Two Scope 2 rules, side by side
| Scope 2 Guidance | UK SRS S2 | |
|---|---|---|
| Location-based | Required | Required (¶29(a)(v), ¶B30) |
| Market-based | Required where contractual instruments exist | Permitted (¶B31) |
| Dual reporting | Yes, conditionally | Not required |
Sources: GHG Protocol Scope 2 Guidance; UK SRS S2
In UK rules
How UK SRS S2 pins the GHG Protocol
UK SRS S2 paragraph 29(a)(ii) requires a company to measure its emissions in accordance with the GHG Protocol Corporate Standard (2004).
The same sentence carries an exception: a different method may be used where a jurisdictional authority or an exchange on which the entity is listed requires it.
Paragraph C3 allows a different measurement method in the first annual reporting period only.
Paragraph C4 relieves a company from disclosing Scope 3 emissions, and unlike C3 it carries no time limit.
Paragraph B32 requires the company to consider all 15 Scope 3 categories and to disclose which are included; considering all fifteen is not the same as reporting all fifteen.
Paragraph 29A lets a company limit Category 15 to its financed emissions and exclude emissions attributable to derivatives.
Under the FCA’s final rules in PS26/19, listed companies in UKLR 6, 14, 15, 16 and 22 report against UK SRS on a comply-or-explain basis for periods beginning on or after 1 January 2027.
UK SRS S2 names the 2004 Corporate Standard.
It does not say whether that reference picks up the 2013 gas amendment and the 2015 Scope 2 Guidance, so we do not assert either reading.
For the full set of UK SRS requirements, see UK SRS requirements; for Scope 3 under it, see UK SRS Scope 3 reporting.
Scope 3
No Scope 3 category is optional under the Scope 3 Standard
| Instrument | Scope 3 position | Provision |
|---|---|---|
| Corporate Standard alone | Optional in full | Ch. 4; Ch. 9; Table 1.1 |
| Scope 3 Standard | All Scope 3 emissions accounted for; exclusions disclosed and justified | §6.2; Table 1.1 |
| UK SRS S2 | Gross Scope 3 required; all 15 categories considered, included ones disclosed; relief with no time limit | ¶29(a)(i)(3), ¶29(a)(vi)(1), ¶B32, ¶B33, ¶C4 |
Lists that rank some categories as “required” and others as “optional” do not come from the Scope 3 Standard.
Its use of “optional” attaches to activities within a category beyond the minimum boundary, never to a category.
A category that does not apply is reported as zero or “not applicable”.
In the UK, DESNZ’s call for evidence on Scope 3 received 184 responses and described Scope 3 reporting as remaining largely voluntary.
The calculation methods for each category are set out on our Scope 3 categories page, and what each scope contains is on Scope 1, 2 and 3 emissions.
What changes next
One consolidated standard, with ISO
In September 2025 the GHG Protocol and ISO announced a partnership whose scope covers the Corporate Standard, the Scope 2 Guidance, the Scope 3 Standard, a new actions and market instruments workstream, and ISO 14064-1.
On 29 July 2026 the GHG Protocol announced that the two bodies are aligning their programmes around a single co-branded corporate standard.
Its Standard Development Plan v2.0 estimates a consolidated draft for public consultation in Q2 2027 and a published revised standard in Q4 2028, and says the timeline is subject to change.
The plan describes a standard delivered in parts, with guidance documents expected after the standard itself.
Both bodies say they remain fully independent and keep authority over their own standards.
Until a revised standard is published, the current documents above remain the ones in use, and UK SRS S2 names the 2004 Corporate Standard.
How ISO 14064-1 relates to the Corporate Standard today is on our ISO 14064 page.
UK data
Accounting rules here, emission factors elsewhere
The GHG Protocol tells a company what to count and how to classify it.
The factors that turn activity data into tonnes usually come from the government’s conversion factors for company reporting, published each year.
The current UK sets and how they changed are on our UK emission factors page.
To talk through how the standards apply to a specific inventory, you can book a free 15-minute call.
Frequently asked
Questions people ask
What is the GHG Protocol?
A set of greenhouse gas accounting standards and guidance. For companies the core documents are the Corporate Accounting and Reporting Standard (revised edition, 2004), the Scope 2 Guidance (2015), which amends it, and the Corporate Value Chain (Scope 3) Standard (2011). They define Scopes 1, 2 and 3 and how an organisation builds an emissions inventory.
Is the GHG Protocol mandatory in the UK?
No UK law requires the GHG Protocol across the board. UK SRS S2 requires emissions to be measured in accordance with the 2004 Corporate Standard, unless a jurisdictional authority or exchange requires another method. Under the FCA’s final rules in PS26/19, listed companies in scope report against UK SRS on a comply-or-explain basis for periods beginning on or after 1 January 2027.
Does the GHG Protocol require Scope 3 reporting?
Not on its own. The Corporate Standard requires a minimum of Scope 1 and Scope 2 and calls Scope 3 optional. A company that reports under the Scope 3 Standard must account for all Scope 3 emissions it defines and disclose and justify any exclusions. UK SRS S2 is different again: it requires gross Scope 3, requires all 15 categories to be considered and the included ones disclosed, and gives a Scope 3 relief with no time limit.
What is the difference between location-based and market-based Scope 2?
The location-based method uses average grid emission factors; the market-based method uses contractual instruments such as supplier-specific factors. The Scope 2 Guidance asks companies with operations in markets offering such instruments to report both. UK SRS S2 requires location-based Scope 2 and permits market-based figures, so it does not require dual reporting.
Is the GHG Protocol being revised?
Yes. In July 2026 the GHG Protocol published a development plan for a single consolidated corporate standard, developed with ISO and covering the Corporate Standard, Scope 2, Scope 3, a new actions and market instruments part and ISO 14064-1. It estimates a draft for public consultation in Q2 2027 and a published standard in Q4 2028, and says the timeline may change.
Does the GHG Protocol publish UK emission factors?
No. The GHG Protocol sets the accounting rules; UK organisations usually take emission factors from the government conversion factors for company reporting, published each year by DESNZ.
Sources
Primary sources
Every figure, date and status on this page traces to the instrument’s owner. Secondary commentary is never the source for a number.
- GHG ProtocolCorporate Accounting and Reporting Standard (revised edition, 2004) — landing page
Seven gases including NF3; updated in 2015 with the Scope 2 Guidance.
- GHG ProtocolCorporate Accounting and Reporting Standard (PDF), Chapters 1, 4 and 9
Scope 3 an optional reporting category; minimum of Scope 1 and Scope 2.
- GHG ProtocolScope 2 Guidance (2015), §7.4
Dual reporting where contractual instruments exist; the two totals are not gross and net.
- GHG ProtocolCorporate Value Chain (Scope 3) Standard (2011), Table 5.4 and §6.2
Fifteen categories; account for all Scope 3 emissions and justify exclusions.
- GHG ProtocolTechnical Guidance for Calculating Scope 3 Emissions
A companion calculation guide; it points to the Standard for requirements.
- GHG ProtocolConsolidated Corporate Standard Development Plan v2.0 (29 July 2026), §§2, 6 and 9
Consultation draft estimated Q2 2027; published standard estimated Q4 2028.
- GHG ProtocolGHG Protocol announces key standard development updates (29 July 2026)
The move to a single co-branded corporate standard with ISO.
- GHG Protocol / ISOISO–GHG Protocol partnership: frequently asked questions
Both bodies remain independent and keep authority over their standards.
- Department for Business and TradeUK SRS S2 Climate-related Disclosures, ¶¶29(a), 29A, B30–B33, C3–C4
GHG Protocol (2004) measurement; location-based Scope 2; Scope 3 categories considered.
- Financial Conduct AuthorityPS26/19: Aligning listed issuers’ sustainability disclosures with international standards
Comply or explain against UK SRS for UKLR 6, 14, 15, 16 and 22, periods from 1 January 2027.
- Department for Energy Security and Net ZeroGovernment conversion factors for company reporting
The annual UK emission factor sets.
- Department for Energy Security and Net ZeroUK greenhouse gas emissions reporting: Scope 3 emissions (call for evidence and outcome)
184 responses; Scope 3 reporting remains largely voluntary.