GHG Protocol Corporate Standard Overview

The GHG Protocol Corporate Accounting and Reporting Standard is the foundation of virtually every corporate carbon inventory in the world. Published by the World Resources Institute (WRI) and the World Business Council for Sustainable Development (WBCSD), the Corporate Standard is referenced by CDP, the EU Taxonomy, CSRD, the Science Based Targets initiative, and the TCFD recommendations. Understanding how it works is essential for any enterprise building a credible GHG reporting programme.

Why the GHG Protocol Matters

Before the GHG Protocol, corporate greenhouse gas accounting lacked a common methodology. Different companies used different system boundaries, different emission factors, and different scope definitions, making disclosure figures incomparable. The Corporate Standard, first published in 2001 and updated in 2004 and through subsequent guidance documents, established the shared methodology that made corporate GHG disclosure comparable and credible.

Today, more than 9 out of 10 Fortune 500 companies that disclose emissions to CDP use the GHG Protocol as their accounting standard. All SBTi target validations require GHG Protocol-consistent inventories. CSRD's ESRS E1 references the GHG Protocol Corporate Standard and the Corporate Value Chain (Scope 3) Standard as the required accounting basis.

The Five Accounting Principles

The GHG Protocol is built on five accounting principles that govern how inventories should be constructed and reported:

• Relevance The GHG inventory should appropriately reflect the GHG emissions of the company and serve the decision-making needs of both internal and external users.
• Completeness Account for and report on all GHG emission sources and activities within the chosen inventory boundary. Disclose and justify any specific exclusions.
• Consistency Use consistent methodologies to allow for meaningful comparisons of emissions over time. Document clearly any changes to the data, inventory boundary, methods, or any other relevant factors in the time series.
• Transparency Address all relevant issues in a factual and coherent manner, based on a clear audit trail. Disclose any relevant assumptions and make appropriate references to the accounting and calculation methodologies and data sources used.
• Accuracy Ensure that the quantification of GHG emissions is systematically neither over nor under actual emissions, as far as can be judged, and that uncertainties are reduced as far as practicable.

Setting Organisational Boundaries

The first task in building a GHG inventory under the Corporate Standard is defining which entities and operations fall within the organisational boundary. The GHG Protocol offers three consolidation approaches:

Equity Share Approach

The company accounts for GHG emissions from operations according to its share of equity in each operation. A 40 percent equity stake in a joint venture means including 40 percent of that facility's emissions. This approach is aligned with financial accounting consolidation and makes it straightforward to cross-reference GHG inventory figures against financial statements.

Financial Control Approach

The company accounts for 100 percent of the GHG emissions from operations over which it has financial control — defined as the ability to direct the financial and operating policies of the entity. A subsidiary over which the parent has financial control is fully consolidated, regardless of percentage ownership.

Operational Control Approach

The company accounts for 100 percent of emissions from operations over which it has operational control — meaning it has the full authority to introduce and implement its operating policies. This is the most common approach for companies with complex ownership structures, franchises, or joint ventures where operational rather than financial authority is clearer.

Setting Operational Boundaries: The Three Scopes

Once organisational boundaries are set, operational boundaries define which emission sources are included. This is where the GHG Protocol's three-scope framework applies.

Scope 1 and Scope 2 reporting is mandatory under the Corporate Standard for any company claiming conformance. Scope 3 reporting is optional under the Corporate Standard itself but is increasingly mandatory under external frameworks (CSRD, CDP, SBTi for companies where Scope 3 exceeds 40 percent of total emissions).

Scope 2 Accounting: Location-Based vs Market-Based

The GHG Protocol Scope 2 Guidance (2015) introduced a dual-reporting requirement that has become one of the more practically complex aspects of corporate GHG accounting. Companies must report both:

• Location-based Scope 2: Uses the average grid emission factor for the geography where electricity is consumed. Reflects the physical carbon content of the electricity grid.
• Market-based Scope 2: Uses emission factors from contractual instruments — primarily Energy Attribute Certificates (EACs) such as Renewable Energy Certificates (RECs), Guarantees of Origin (GOs) in Europe, and International RECs (I-RECs) in other markets. If a company has purchased renewable energy certificates covering 100 percent of its consumption, its market-based Scope 2 can be zero.

The practical implication is that a company purchasing renewable electricity from a 100-percent renewables supplier in a coal-heavy grid will report very different location-based and market-based Scope 2 figures. Both must be disclosed. The SBTi and most regulatory frameworks base target setting on market-based Scope 2, while the location-based figure provides context for the physical grid reality.

Gases Covered by the Corporate Standard

The GHG Protocol covers the six greenhouse gases listed under the Kyoto Protocol, plus additional fluorinated gases and precursor substances:

• Carbon dioxide (CO2)
• Methane (CH4)
• Nitrous oxide (N2O)
• Hydrofluorocarbons (HFCs)
• Perfluorocarbons (PFCs)
• Sulphur hexafluoride (SF6)
• Nitrogen trifluoride (NF3)

All gases are converted to a carbon dioxide equivalent (CO2e) using Global Warming Potentials (GWPs) from the IPCC. The GHG Protocol recommends using GWP values from the IPCC Fifth Assessment Report (AR5), though many regulatory frameworks now reference AR6 values published in 2021. The choice of GWP vintage must be disclosed.

Base Year and Recalculation Policy

Companies are required to select a base year against which emission trends will be measured. The GHG Protocol specifies that when significant structural changes occur — mergers, acquisitions, divestitures, changes to the consolidation approach — the base year inventory must be recalculated to allow like-for-like comparison. A recalculation policy should define the threshold at which a change triggers mandatory restatement (commonly a five percent significance threshold).

Without a consistent recalculation policy, year-over-year emission figures become incomparable and targets become meaningless — a company can appear to reduce emissions simply by divesting high-emission assets without actually decarbonising its remaining operations.

Relationship to Other Standards

The GHG Protocol Corporate Standard is the parent framework. A family of supplementary standards extends it:

• Corporate Value Chain (Scope 3) Standard: Detailed methodology for the 15 Scope 3 categories. Essential for any company with material Scope 3 emissions.
• Product Life Cycle Accounting Standard: For quantifying emissions across the full life cycle of a specific product or service.
• Land Sector and Removals Guidance: For companies with forestry, agriculture, or land-based carbon removal activities.
• Mitigation Goal Standard: For setting and tracking GHG mitigation goals. Less commonly used than SBTi's goal-setting framework.

Practical Implications for Carbon Tracking Software

A carbon tracking platform that claims GHG Protocol conformance must implement several specific requirements:

• Support for all three consolidation approaches with entity-level boundary tracking
• Dual-method Scope 2 calculation (location-based and market-based)
• Versioned emission factor libraries with disclosure of source and vintage
• Base year management with recalculation workflow
• Audit trail linking every emission figure to its source data and the calculation applied
• Support for all six Kyoto gases with AR5/AR6 GWP selection

When evaluating carbon software, ask the vendor specifically which version of the GHG Protocol their methodology implements, whether they support the Scope 2 Guidance dual-method requirement, and how their platform handles base year recalculations when the organisational boundary changes.