GHG Protocol Guide: Corporate Emissions Accounting

Overview

The Greenhouse Gas Protocol (GHG Protocol) is the world's most widely used greenhouse gas accounting framework. Developed by the World Resources Institute (WRI) and the World Business Council for Sustainable Development (WBCSD), the GHG Protocol provides the standardized methodologies that underpin virtually every corporate emissions reporting framework, regulatory mandate, and target-setting initiative in existence.

The GHG Protocol suite includes the Corporate Accounting and Reporting Standard (revised in 2004), the Corporate Value Chain (Scope 3) Standard (2011), the Scope 2 Guidance (2015), and several sector-specific calculation tools. Together, these standards define how organizations establish emissions inventories, set organizational and operational boundaries, calculate emissions across three scopes, and report results with accuracy and transparency.

Understanding the GHG Protocol is not optional for any organization engaged in climate disclosure. The SEC climate rules, California's SB 253, the CSRD, ISSB standards, CDP, and the Science Based Targets initiative all reference or require the GHG Protocol as the basis for emissions quantification. Mastering this framework is the foundation on which all other climate reporting obligations are built.

Who Does It Apply To?

The GHG Protocol is a voluntary standard, but it has become mandatory by reference through numerous regulations and frameworks:

• Any company reporting GHG emissions under the SEC climate rules, SB 253, CSRD, ISSB, CDP, or other frameworks that reference the GHG Protocol
• Companies setting science-based targets through the SBTi, which requires GHG Protocol-based inventories
• Financial institutions assessing portfolio emissions under PCAF, which builds on GHG Protocol methodologies
• Companies participating in carbon markets or purchasing offsets, which need robust baseline inventories
• Supply chain participants responding to customer emissions data requests

In practice, any organization that measures, reports, or makes claims about its greenhouse gas emissions should use the GHG Protocol. It is the lingua franca of corporate carbon accounting.

Key Requirements

1. Organizational Boundaries Define your organizational boundary using either the equity share approach (accounting for emissions proportional to ownership stake) or the control approach (accounting for 100% of emissions from operations you control, either financially or operationally). The choice of approach affects which facilities and operations are included in your inventory and must be applied consistently.

2. Operational Boundaries and Scope Definitions Classify emissions into three scopes:

• Scope 1: Direct emissions from owned or controlled sources (combustion, process emissions, fugitive emissions, mobile sources)
• Scope 2: Indirect emissions from purchased electricity, steam, heating, and cooling
• Scope 3: All other indirect emissions in the value chain, across 15 defined categories

3. Scope 2 Reporting: Dual Reporting The 2015 Scope 2 Guidance requires dual reporting of Scope 2 emissions using both the location-based method (average grid emission factors) and the market-based method (emission factors from contractual instruments like RECs, PPAs, and green tariffs). Both figures must be reported.

4. Scope 3 Categories The Corporate Value Chain Standard defines 15 categories of Scope 3 emissions:

• Upstream: purchased goods/services, capital goods, fuel/energy-related activities, upstream transportation, waste, business travel, employee commuting, upstream leased assets
• Downstream: downstream transportation, processing of sold products, use of sold products, end-of-life treatment, downstream leased assets, franchises, investments

5. Calculation Approaches The GHG Protocol provides multiple calculation approaches depending on data availability:

• Direct measurement (continuous emissions monitoring)
• Calculation-based (activity data × emission factor)
• Spend-based estimation (financial expenditure × economic emission factor) Each approach has different accuracy levels and data requirements.

6. Reporting Principles Five principles govern GHG Protocol reporting: relevance, completeness, consistency, transparency, and accuracy. Reports must include base year emissions, recalculation policies, boundary descriptions, methodology explanations, and uncertainty assessments.

7. Base Year and Recalculation Establish a base year against which progress is measured. Define a recalculation policy that specifies when the base year inventory must be recalculated (e.g., structural changes like acquisitions, methodology changes, or discovery of significant errors). Consistent recalculation ensures that reported trends reflect genuine emissions changes, not accounting artifacts.

Timeline & Milestones

The GHG Protocol is currently undergoing a comprehensive update—the first major revision in over a decade. The update is expected to address topics including market-based accounting for Scope 2 and 3, land use emissions, biogenic carbon, and improved Scope 3 guidance. Companies should monitor the update process and prepare to adapt their inventories.

Step-by-Step Compliance Roadmap

Step 1: Define Boundaries and Scope

Select your organizational boundary approach (equity share or control) based on your corporate structure and reporting objectives. Map all facilities, operations, and value chain relationships. Define which Scope 3 categories are relevant and material to your business. Document these decisions—they form the foundation of your inventory and must be applied consistently.

Step 2: Collect Activity Data

Identify and collect activity data for each emission source within your boundaries. For Scope 1, this includes fuel consumption, process activity, and refrigerant use. For Scope 2, collect electricity, steam, and heating/cooling consumption data along with contractual instruments. For Scope 3, collect data from suppliers, logistics providers, travel systems, and other value chain partners. Establish data collection processes and assign data owners.

Step 3: Calculate Emissions

Apply appropriate emission factors to activity data. Use the most specific, accurate factors available—facility-specific factors are preferable to national averages, which are preferable to global defaults. For Scope 2, calculate both location-based and market-based figures. For Scope 3, use the calculation approach best suited to each category based on data availability. Document all emission factors, sources, and assumptions.

Step 4: Verify and Quality-Check

Implement quality assurance and quality control procedures. Cross-check activity data against prior years and expected ranges. Verify emission factor appropriateness. Reconcile bottom-up calculations with top-down estimates where possible. Conduct internal reviews and, where required by reporting frameworks, engage external verifiers.

Step 5: Report and Establish Base Year

Compile your emissions inventory report following GHG Protocol reporting requirements. Establish your base year and recalculation policy. Disclose methodology, assumptions, data sources, and known limitations transparently. Submit data to relevant reporting frameworks (CDP, regulatory bodies) and publish where appropriate.

Common Pitfalls

Inconsistent organizational boundaries. Companies that change their organizational boundary approach between reporting years—or apply it inconsistently across business units—produce inventories that are not comparable over time. Choose your approach thoughtfully and apply it rigorously.

Neglecting Scope 2 dual reporting. The 2015 Scope 2 Guidance requires both location-based and market-based reporting. Companies that report only one method are non-compliant with the standard. Both figures serve different analytical purposes and stakeholders expect both.

Cherry-picking Scope 3 categories. While not all 15 categories will be material for every company, the decision to exclude categories must be justified and documented. Companies that report only the categories where their emissions are low, while omitting high-impact categories, undermine credibility.

Using outdated emission factors. Emission factors are updated regularly as grid carbon intensity changes and measurement methodologies improve. Using factors from five years ago introduces systematic error. Establish a process for updating emission factors annually.

How Council Fire Can Help

Council Fire helps organizations build GHG inventories that are technically robust and strategically meaningful. We view emissions accounting not as an end in itself but as the analytical foundation for credible climate strategy, target-setting, and stakeholder engagement.

Our team has deep experience with the complexities that trip up even sophisticated reporters: Scope 2 market instruments, Scope 3 category prioritization, base year recalculation, and the methodological choices that determine whether your inventory withstands external scrutiny.

For organizations with ocean-related value chains—shipping, fisheries, aquaculture, coastal tourism—Council Fire brings sector-specific expertise to emissions calculation that generic consultancies often lack. Maritime emissions, in particular, involve specialized methodologies and data sources.

Council Fire also connects GHG Protocol implementation to broader strategic objectives. We ensure that the data architecture built for emissions reporting also supports target-setting, transition planning, and investor communication—turning a compliance requirement into a strategic asset.

Frequently Asked Questions

What is the difference between Scope 2 location-based and market-based methods?

The location-based method reflects the average emissions intensity of the electricity grid where consumption occurs, using grid-average emission factors. The market-based method reflects the emissions attributes of the specific electricity a company has chosen—through renewable energy certificates (RECs), power purchase agreements (PPAs), green tariffs, or other contractual instruments. Both must be reported. The location-based figure shows physical grid reality; the market-based figure reflects procurement decisions. Discrepancies between the two reveal the extent to which a company's renewable energy claims translate into actual grid decarbonization.

Do we have to report all 15 Scope 3 categories?

You must evaluate all 15 categories for relevance and report those that are significant to your business. The GHG Protocol Scope 3 Standard provides screening criteria to determine significance based on size, influence, risk, stakeholder interest, and outsourcing patterns. You may exclude categories that are genuinely immaterial, but you must disclose which categories are excluded and explain why. Most companies find that 5–8 categories account for the vast majority of their Scope 3 footprint.

How often should we update our GHG inventory?

Most reporting frameworks require annual reporting of Scope 1 and 2 emissions. Scope 3 reporting frequency varies by framework—SBTi requires annual reporting, while some regulatory frameworks allow less frequent updates. Regardless of external requirements, annual inventory updates are best practice, as they enable trend analysis, target tracking, and timely identification of emission drivers. Your base year should be recalculated when structural changes, methodology improvements, or data errors warrant it.