GHG Protocol: Complete Guide to Greenhouse Gas

Companies already generate environmental data through energy use, fuel consumption, purchased goods, travel, production and suppliers. The challenge is structuring that information so it can support carbon accounting, savings analysis and operational decisions.

The GHG Protocol is the most widely used international framework for measuring and managing greenhouse gas emissions. Developed by the World Resources Institute (WRI) and the World Business Council for Sustainable Development (WBCSD), it provides the foundational standard for corporate carbon accounting across industries and geographies.

Whether your company is preparing CSRD disclosures, setting science-based targets, or simply trying to understand its environmental impact, the GHG Protocol is where carbon accounting begins.

Instead of collecting the same information separately for every disclosure, audit or questionnaire, companies can structure their environmental data once and reuse it across reporting, savings analysis and operational decisions.

What is the GHG Protocol?

The GHG Protocol establishes standardised frameworks for measuring greenhouse gas emissions at the corporate and product level. First published in 2001, it has become the de facto global standard and is used by more than 90% of Fortune 500 companies that disclose their emissions.

The protocol covers all seven greenhouse gases defined by the Kyoto Protocol:

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

All emissions are expressed in metric tonnes of carbon dioxide equivalent (tCO₂e).

The three scopes of emissions

The GHG Protocol’s most important contribution is the classification of emissions into three scopes, which together capture a company’s complete carbon footprint.

Scope 1: Direct emissions

Scope 1 emissions come from sources owned or controlled by the company. These include:

• Fuel combustion in company vehicles
• On-site heating from natural gas boilers
• Industrial processes that release GHGs
• Refrigerant leaks from HVAC systems

For manufacturing and transport companies, Scope 1 is often the largest emissions category. For service-based businesses, it typically represents a smaller share. Scope 1 data usually comes from operational records that companies already hold, such as fuel purchases, meter readings, vehicle logs and process measurements.

Scope 2: Energy indirect emissions

Scope 2 emissions result from the generation of purchased electricity, steam, heating and cooling. The GHG Protocol requires companies to calculate Scope 2 using two methods:

• Location-based: Uses average grid emission factors for the region
• Market-based: Uses emission factors from contractual instruments (RECs, PPAs, green tariffs)

Using both methods gives stakeholders a more complete picture of electricity-related emissions. It also helps companies understand the difference between emissions associated with the local grid and emissions linked to the electricity products they have purchased.

Scope 3: Value chain emissions

Scope 3 emissions cover all other indirect emissions across the value chain. The GHG Protocol defines 15 categories, split between upstream activities such as purchased goods, business travel and employee commuting, and downstream activities such as the use of sold products and end-of-life treatment.

For most companies, Scope 3 represents between 70% and 90% of total emissions. It is also the hardest scope to measure because it requires information from suppliers, customers and other third parties.

The quality of Scope 3 calculations depends on the quality of purchasing, supplier, logistics and activity data. Estimates can provide a starting point, but companies need more specific information as their data processes mature.

Key standards within the GHG Protocol

The GHG Protocol is not a single document. It is a family of standards and guidance documents that address different types of carbon accounting.

Corporate Standard

The Corporate Standard is the foundational framework for company-level GHG inventories. It covers how to set organisational and operational boundaries, choose a base year, collect activity data and calculate emissions across all three scopes.

Scope 3 Standard (Corporate Value Chain)

Published in 2011, the Scope 3 Standard provides detailed guidance for quantifying emissions across all 15 categories. It includes calculation approaches ranging from spend-based estimates to supplier-specific data.

Companies can use different approaches depending on data availability, materiality and the level of precision required.

Product Standard

The Product Standard focuses on lifecycle emissions of individual products using life cycle assessment (LCA) methodologies. It is useful for Environmental Product Declarations (EPDs), product carbon footprints and design decisions.

Product-level information can also support procurement, customer requests and comparisons between materials or production methods.

Project Protocol

The Project Protocol quantifies greenhouse gas reductions from specific mitigation projects. It is used primarily for carbon-offset verification and for assessing whether a project has achieved the claimed reduction.

How the GHG Protocol connects to CSRD

The Corporate Sustainability Reporting Directive (CSRD) requires companies to disclose their climate impact following the European Sustainability Reporting Standards (ESRS). Under ESRS E1, which covers climate change, emissions must be calculated using GHG Protocol methodologies.

Specifically, CSRD-compliant reports must include:

• Scope 1 emissions.
• Scope 2 emissions using both location-based and market-based methods.
• Material Scope 3 categories where applicable.
• A base year and an explanation of the methodology.
• Emission-intensity metrics.

Companies already using the GHG Protocol have a strong foundation for preparing CSRD outputs. However, CSRD adds requirements around transition plans, targets, governance and evidence that go beyond measuring emissions alone.

This means companies need more than a one-time carbon calculation. They need traceable data that can be connected to business risks, opportunities, investments and operational actions.

Getting started with GHG Protocol reporting

The typical process for a first GHG inventory follows these steps:

1. Define boundaries: Choose between the equity-share and operational-control approaches. Document which entities, facilities, activities and reporting periods are included. Clear boundaries prevent gaps and make year-on-year comparisons more reliable.
2. Identify emission sources: Map all relevant sources across Scopes 1, 2 and 3. This includes owned equipment, purchased electricity, vehicles, buildings, materials, suppliers, travel, logistics and the use or disposal of sold products.
3. Collect activity data: Gather fuel consumption, electricity use, travel records, procurement information and supplier data. Each input should have a defined owner, source, unit, reporting period and evidence requirement.
4. Apply emission factors: Multiply activity data by scientifically validated emission factors. Record the source, version and geographic relevance of every factor. If a factor changes, document how that change affects the result.
5. Calculate and verify: Aggregate the results and conduct quality checks. Review unusual changes, missing data, unit conversions, calculation formulas and the consistency of assumptions across sites and business units.
6. Report and improve: Disclose the findings, set reduction targets and use the results to prioritise operational action.

The inventory should become a repeatable management process rather than an annual exercise completed only to satisfy a disclosure deadline.

Automating GHG Protocol reporting

Manual carbon accounting is time-consuming and error-prone. Modern environmental data platforms can automate the process by connecting directly to data sources, ERP systems, utility providers and fleet-management tools while applying region-specific emission factors.

Dcycle structures information from energy, fuel, purchasing, suppliers, travel and operational systems so the same environmental data can serve different teams.

For example, purchasing data can support Scope 3 calculations, supplier evaluations and cost analysis. Energy data can support Scope 2 calculations, efficiency projects and investment decisions.

This approach helps companies reduce duplicate requests, maintain clearer evidence and update calculations when suppliers, facilities or methodologies change.

Key takeaways

The GHG Protocol remains the global standard for corporate greenhouse gas accounting.

Its three scopes help companies understand direct emissions, purchased energy and the wider value chain. For most organisations, Scope 3 represents the largest share of their footprint and requires the greatest improvement in data quality.

Companies that already structure their environmental data around the GHG Protocol have a stronger foundation for CSRD and ESRS E1 disclosures.

However, reliable carbon accounting should support more than compliance. It should help teams identify savings opportunities, set reduction targets, assess suppliers and make better operational decisions.

Automation reduces the time and cost of collecting, calculating and validating emissions data. When the information is structured once, it can support reporting, savings analysis and continuous improvement across the organisation.

Frequently asked questions (FAQs)