The complete guide to GHG Protocol reporting

The Greenhouse Gas Protocol publishes standards for measuring and reporting corporate greenhouse gas emissions. Its Corporate Accounting and Reporting Standard (the Corporate Standard) defines how a company sets the boundaries of its inventory,¹ with separate guidance for Scope 2⁵ and a standard for the value chain, Scope 3.⁷ This guide summarises the core rules, each linked to its source.

1. The five principles

The Corporate Standard says a GHG inventory should be based on five principles:²

• Relevance: the inventory appropriately reflects the company's emissions.
• Completeness: it accounts for all emission sources and activities within the chosen boundary.
• Consistency: methodologies stay consistent so emissions can be compared over time.
• Transparency: all relevant issues are addressed factually and coherently, based on a clear audit trail.
• Accuracy: quantification is systematically neither over nor under actual emissions.

2. The seven gases

Companies must account for and report emissions of seven greenhouse gases: carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulphur hexafluoride (SF₆) and nitrogen trifluoride (NF₃).³ Each is converted to carbon dioxide equivalent (CO₂e) so the inventory can be reported as one total.

3. Setting the organisational boundary

Before counting emissions, a company decides which operations belong in its inventory. The GHG Protocol offers three consolidation approaches:¹

• Equity share: account for emissions according to your share of equity in each operation.
• Financial control: account for 100 percent of the emissions from operations you control financially. Financial control is possible with less than 50 percent equity.
• Operational control: account for 100 percent of the emissions from operations you control operationally. The US EPA describes this as the most common approach.

The EPA notes that the approach you choose also affects how emissions are treated in Scope 3.¹

4. The three scopes

Scope 1: direct emissions

Direct emissions from sources the organisation owns or controls, such as fuel burned in boilers, furnaces and vehicles.⁴ The EPA's Scope 1 and 2 guidance also covers fugitive emissions, such as those from refrigeration and air-conditioning equipment.⁴

Scope 2: purchased energy

Indirect emissions from the purchase of electricity, steam, heat or cooling. The emissions physically occur where the energy is generated, but they are counted by the organisation that uses it.⁴ Purchased cooling, including district cooling, therefore falls under Scope 2.

The GHG Protocol's Scope 2 Guidance requires dual reporting, with two totals:⁵

• Location-based: uses grid-average emission factors. It can only be reduced by using less energy.
• Market-based: reflects the emissions from the electricity a company is purchasing, which may differ from the electricity generated locally.

Companies choose which total to use for tracking performance, but must disclose that choice.⁵

Scope 3: the value chain

Scope 3 includes all sources not within an organisation's Scope 1 and 2 boundary. One organisation's Scope 3 emissions are the Scope 1 and 2 emissions of another, and they often represent the majority of a company's total emissions.⁶

5. The 15 Scope 3 categories

The Scope 3 Standard divides value-chain emissions into 15 categories, designed to be mutually exclusive so nothing is counted twice. They are split into upstream (purchased goods and services) and downstream (sold goods and services) according to the company's financial transactions.⁷

Category names as listed by the US EPA.⁶

6. Deciding what to measure first

Not every category will be material. The GHG Protocol suggests screening first: estimate each Scope 3 activity and rank them from largest to smallest. Companies can also prioritise by financial significance, influence, risk exposure, or what stakeholders consider critical.⁷

The Scope 3 Standard sets minimum boundaries for each category. Companies may go beyond them or exclude required activities, provided they clearly disclose and justify any exclusions.⁷

7. The standards are being revised

The GHG Protocol is updating its standards. As of mid-2026, a first draft of a unified corporate standard is expected in the second quarter of 2027, set to take effect in 2028. A Scope 3 consultation draft is due in the second half of 2026, and the Scope 2 revision is working through around 1,100 consultation comments.⁸

Quick reference

Sources

1. US Environmental Protection Agency, “Determine Organizational Boundaries”, Center for Corporate Climate Leadership. epa.gov ↗
2. Deloitte, “Accounting and Reporting Principles”, Greenhouse Gas Protocol Reporting Considerations (quoting the GHG Protocol Corporate Standard, Chapter 1). dart.deloitte.com ↗
3. GHG Protocol, “Required Greenhouse Gases in Inventories” (accounting and reporting standard amendment). ghgprotocol.org ↗
4. US Environmental Protection Agency, “Scope 1 and Scope 2 Inventory Guidance”, Center for Corporate Climate Leadership. epa.gov ↗
5. GHG Protocol, “Top ten questions about Scope 2 Guidance”. ghgprotocol.org ↗
6. US Environmental Protection Agency, “Scope 3 Inventory Guidance”, Center for Corporate Climate Leadership. epa.gov ↗
7. GHG Protocol, “Scope 3 Frequently Asked Questions”. ghgprotocol.org ↗
8. Trellis, “GHG Protocol adjusts standards update timelines”, 29 July 2026. trellis.net ↗