What is the GHG Protocol?
The Greenhouse Gas Protocol — universally known as the GHG Protocol — is the world's most widely used standard for measuring, managing, and reporting corporate greenhouse gas emissions. Developed through a partnership between the World Resources Institute (WRI) and the World Business Council for Sustainable Development (WBCSD), it provides the foundational framework that underpins virtually every corporate carbon reporting requirement globally. When a UK company reports emissions under SECR, they are using GHG Protocol methodology. When a European company discloses under CSRD, the underlying accounting framework is the GHG Protocol. When a company sets targets through the Science Based Targets initiative, those targets are measured against a GHG Protocol-compliant inventory. The Protocol is so deeply embedded in global carbon accounting that most practitioners use its concepts — scopes, organisational boundaries, operational control — without explicitly referencing the source. The GHG Protocol establishes several critical foundations: The three-scope framework: The division of emissions into Scope 1 (direct), Scope 2 (purchased energy), and Scope 3 (value chain) — which has become the universal language of corporate carbon accounting. Five accounting principles: Relevance (the inventory appropriately reflects the company's emissions), completeness (all material emission sources are included), consistency (methodologies allow meaningful comparison over time), transparency (assumptions and methodologies are documented), and accuracy (the inventory is not systematically biased). Organisational boundary approaches: Two methods for determining which entities and operations to include — the equity share approach (based on ownership percentage) and the control approach (based on operational or financial control). UK SECR reporting typically uses the operational control approach. Calculation methodologies: Standardised approaches for calculating emissions from different source types, including fuel combustion, electricity consumption, industrial processes, and fugitive emissions.
The key standards and their application
The GHG Protocol is not a single document but a suite of interconnected standards, each addressing a different aspect of greenhouse gas accounting: The Corporate Accounting and Reporting Standard (the Corporate Standard): Published in 2004 and revised in 2015, this is the foundation document for corporate-level GHG accounting. It covers Scope 1 and 2 emissions, sets out the accounting principles, defines organisational and operational boundaries, and provides guidance on base year selection, recalculation, and reporting. For UK companies producing SECR reports, this is the primary reference standard. The Corporate Value Chain Standard (the Scope 3 Standard): Published in 2011, this extends corporate accounting into the full value chain. It defines the 15 categories of Scope 3 emissions, provides calculation guidance for each category (including spend-based, average-data, and supplier-specific methods), and establishes the concept of Scope 3 screening to identify material categories. As Scope 3 reporting moves from voluntary to mandatory under CSRD and UK SRS, this standard is becoming essential reading. The Scope 2 Guidance: An amendment to the Corporate Standard published in 2015 that introduced the dual reporting requirement — both location-based and market-based methods for Scope 2. This guidance is particularly relevant for companies purchasing renewable electricity and wanting to reflect that in their reporting. The Product Standard: Published in 2011, this provides methodology for calculating the lifecycle emissions of individual products and services — from raw material extraction through production, distribution, use, and end-of-life. Product-level carbon footprinting is gaining traction as companies face pressure to label products with their carbon impact. The GHG Protocol for Cities: A framework for city-level emissions inventories, used by local authorities and city governments. While not directly relevant to most corporate reporting, it demonstrates the Protocol's versatility across different organisational types.
How the GHG Protocol connects to UK regulations
For UK organisations, the GHG Protocol is not just a recommended framework — it is the methodological foundation on which UK regulations are built. SECR (Streamlined Energy and Carbon Reporting): The UK Government's guidance on SECR reporting explicitly references the GHG Protocol Corporate Standard as the recommended methodology. DEFRA's annual emission factors — the conversion factors used to translate activity data (litres of fuel, kWh of electricity) into CO₂e figures — are designed to be applied within a GHG Protocol-compliant framework. UK SRS (anticipated): The UK Sustainability Reporting Standards, expected to align with the ISSB standards (IFRS S1 and S2), will require climate-related disclosures that build on GHG Protocol accounting. Companies with robust GHG Protocol-compliant inventories will find the transition to UK SRS significantly smoother than those starting from scratch. CDP: The Carbon Disclosure Project, one of the most widely used voluntary disclosure frameworks, requires respondents to report emissions using GHG Protocol methodology. CDP scores heavily weight the quality and completeness of the underlying GHG inventory. SBTi: Science-based targets are set and tracked against GHG Protocol-compliant base year inventories. Without a credible Protocol-compliant inventory, you cannot validate targets through the SBTi. The practical implication is clear: investing in a GHG Protocol-compliant accounting infrastructure is not just about meeting one regulation — it is the foundation that serves every reporting obligation you will face, now and in the future.
Common misconceptions
Despite its widespread adoption, several misconceptions about the GHG Protocol persist: "The GHG Protocol tells you what emission factors to use." It does not. The Protocol provides the accounting framework — the structure, principles, and methodology. Emission factors are published separately by national governments (DEFRA in the UK, EPA in the US) and international bodies (IPCC). The Protocol tells you how to apply factors; the factors themselves come from elsewhere. "GHG Protocol compliance means your numbers are accurate." Compliance means your methodology is sound and consistently applied. Accuracy depends on the quality of your input data. A GHG Protocol-compliant inventory built on estimated data is less accurate than one built on metered data — but both are compliant. The Protocol requires you to document your data quality and improve it over time. "You need to report all 15 Scope 3 categories." The Scope 3 Standard requires you to screen all 15 categories to identify which are material, but you only need to report in detail on the material ones. For most companies, 3-5 categories dominate the Scope 3 total. "The GHG Protocol is being replaced by ISSB/CSRD." It is not. Both the ISSB standards and the CSRD build on GHG Protocol methodology as the underlying accounting framework. They add disclosure requirements on top of it (governance, strategy, risk management, targets) but the core emissions accounting remains GHG Protocol-based. Understanding the GHG Protocol is not an academic exercise — it is the practical foundation for producing credible, comparable, and auditable emissions reports that satisfy every framework your organisation will encounter.