GHG Protocol vs ISO 14064-1: Alignment & When to Use Each

Origins and Purpose of Each Framework

Understanding the provenance of these two frameworks is essential for appreciating why they differ and where they converge. Both were created to standardize greenhouse gas accounting, yet they emerged from different institutional traditions and serve overlapping but distinct audiences.

The GHG Protocol Corporate Standard

The GHG Protocol was launched in 1998 as a joint initiative between the World Resources Institute (WRI) and the World Business Council for Sustainable Development (WBCSD). The first edition of the Corporate Accounting and Reporting Standard was published in 2001, with a revised edition following in 2004. A companion Corporate Value Chain (Scope 3) Accounting and Reporting Standard was added in 2011 and a Scope 2 Guidance amendment in 2015.

The Protocol was designed primarily for voluntary corporate disclosure. It provides detailed, prescriptive guidance on how to account for and report greenhouse gas emissions across three "scopes" — a concept the Protocol popularized and that has since become ubiquitous in corporate sustainability reporting. WRI and WBCSD intended the Protocol to be a practical, step-by-step guidebook rather than a standard in the formal ISO sense, which is why it reads more like a manual and includes extensive worked examples, decision trees, and sector-specific supplements.

Over two decades, the GHG Protocol has become the de-facto global language for corporate carbon accounting. More than 90 percent of Fortune 500 companies that disclose emissions reference the GHG Protocol, and major reporting platforms — CDP, GRI, TCFD, and now ISSB — have adopted its scope framework as a shared taxonomy.

ISO 14064-1: International Standardization

ISO 14064-1 was first published in 2006 by the International Organization for Standardization as part of a three-part series: Part 1 covers organizational-level quantification and reporting, Part 2 addresses project-level quantification, and Part 3 provides requirements for validation and verification. A major revision was published in 2018 as ISO 14064-1:2018 — Greenhouse gases — Part 1: Specification with guidance for the quantification and reporting of greenhouse gas emissions and removals.

The 2018 revision is significant because it moved away from a simple three-scope model toward a six-category classification of indirect emissions and placed greater emphasis on indirect-emission quantification — effectively responding to the growing importance of value-chain emissions. Unlike the GHG Protocol, ISO 14064-1 is a formal international standard, which means it can serve as the basis for accredited third-party verification under ISO 14064-3 and ISO 17029. Organizations seeking an independent assurance statement on their emissions inventory often find ISO 14064-1 to be the natural criteria document because it was explicitly designed for that purpose.

ISO 14064-1 draws on the same IPCC scientific basis as the GHG Protocol but adopts the language and structure of ISO management system standards. It is performance-based rather than prescriptive: it tells organizations what they must achieve (e.g., "identify and document direct GHG emissions") without dictating a single method for doing so. This design philosophy gives organizations more discretion but also means they need to make — and justify — more decisions themselves.

Structural Comparison

At the highest level, both frameworks guide organizations through the same logical sequence: define organizational boundaries, identify emission sources, quantify emissions, and report. However, the structure and depth of each step differ considerably.

Organizational Boundaries

Defining the organizational boundary is the first substantive step in any GHG inventory, and it determines which facilities, operations, and entities are included. The two frameworks approach this differently.

GHG Protocol Approach

The GHG Protocol offers three consolidation approaches for organizational boundaries:

• Equity Share: The organization accounts for emissions from operations according to its percentage of equity ownership. A 50 percent joint-venture interest means 50 percent of that venture's emissions are included.
• Operational Control: The organization accounts for 100 percent of emissions from operations over which it has operational control — the authority to introduce and implement operating policies.
• Financial Control: The organization accounts for 100 percent of emissions from operations over which it has financial control — the ability to direct the financial and operating policies to obtain economic benefits.

Once a consolidation approach is selected, it must be applied consistently across all operations. The GHG Protocol recommends that organizations choose the approach that best reflects the economic substance of their relationships and report that choice transparently.

ISO 14064-1 Approach

ISO 14064-1:2018 does not prescribe specific consolidation approaches. Instead, it requires the organization to "establish and document the organizational boundary" and to "describe the approach used to define the organizational boundary." The standard references control-based and equity-share approaches as examples but explicitly permits other methods if the organization can justify them.

This flexibility is intentional: ISO 14064-1 was written to accommodate a wide range of organizational structures, including government entities, not-for-profits, and complex conglomerates where the GHG Protocol's three approaches may not fit neatly. The trade-off is that the organization bears the burden of documenting and defending its chosen approach, which a verifier will scrutinize.

Scopes vs Categories: The Core Structural Difference

The most frequently cited difference between the two frameworks is how they classify emissions. Understanding this distinction is critical for organizations that must report under both.

GHG Protocol: Three Scopes

The GHG Protocol's three-scope model has become the universal language of carbon accounting:

• Scope 1 — Direct Emissions: Emissions from sources owned or controlled by the reporting company (e.g., combustion in owned boilers, fleet vehicles, fugitive emissions).
• Scope 2 — Energy Indirect Emissions: Emissions from the generation of purchased electricity, steam, heating, and cooling consumed by the reporting company.
• Scope 3 — Other Indirect Emissions: All other indirect emissions in the company's value chain, organized into 15 upstream and downstream categories (e.g., purchased goods and services, business travel, employee commuting, end-of-life treatment of sold products).

ISO 14064-1: Six Categories

ISO 14064-1:2018 classifies emissions into six categories:

• Category 1 — Direct GHG emissions and removals: Equivalent to Scope 1.
• Category 2 — Indirect GHG emissions from imported energy: Equivalent to Scope 2.
• Category 3 — Indirect GHG emissions from transportation: Upstream and downstream transportation and distribution.
• Category 4 — Indirect GHG emissions from products used by the organization: Purchased goods and services, capital goods, waste generated in operations, fuel- and energy-related activities not in Category 2.
• Category 5 — Indirect GHG emissions associated with the use of products from the organization: Processing of sold products, use of sold products, end-of-life treatment of sold products, downstream leased assets, franchises, investments.
• Category 6 — Indirect GHG emissions from other sources: Any indirect emissions not captured by Categories 2–5, such as employee commuting or business travel.

The six-category structure was introduced in the 2018 revision specifically to provide finer granularity for indirect emissions — an area where the earlier three-scope model was considered too coarse for verification purposes. Categories 3 through 6 collectively map to GHG Protocol Scope 3 but divide those emissions along different lines.

Consolidation Approaches Compared

The choice of consolidation approach can materially change the total reported emissions, especially for organizations with joint ventures, franchises, or leased assets. Both frameworks acknowledge this but handle it differently.

Under the GHG Protocol, an organization reports using one of the three named approaches and must restate historical data if it changes approaches. The Protocol gives detailed guidance on how to handle structural changes (mergers, acquisitions, divestitures) and requires a base-year recalculation policy.

Under ISO 14064-1, the organization defines and documents its boundary approach without being constrained to named options. This can be an advantage for entities like municipalities, universities, or sovereign wealth funds that do not map cleanly onto equity-share or control approaches. However, it requires more rigorous documentation to satisfy a verifier that the approach is complete, consistent, and appropriate.

In practice, most organizations that report under both frameworks select operational control as their consolidation approach. This approach is accepted by both the GHG Protocol and ISO 14064-1, produces a single boundary for both reports, and aligns with how most companies manage environmental responsibilities.

Where the GHG Protocol and ISO 14064-1 Align

Despite their structural differences, the two frameworks share a substantial common foundation:

• GHG coverage: Both require reporting of all seven greenhouse gases specified by the Kyoto Protocol and Paris Agreement — CO₂, CH₄, N₂O, HFCs, PFCs, SF₆, and NF₃.
• Scientific basis: Both reference IPCC emission factors and global warming potentials (GWPs). The choice of GWP time horizon (100-year is standard) and IPCC Assessment Report edition should be consistent.
• Quantification methods: Both accept calculation-based methods (activity data × emission factor) and direct measurement. Both recognize the hierarchy: direct measurement > facility-specific factors > regional/national factors > international defaults.
• Base year: Both require a base year and policies for recalculation upon structural or methodological changes.
• Transparency principles: Both require disclosure of methodologies, emission factors, assumptions, and exclusions.
• Biogenic emissions: Both require separate reporting of biogenic CO₂ emissions (from biomass combustion) outside the main inventory total.
• Uncertainty: Both acknowledge quantification uncertainty. ISO 14064-1 is more explicit about requiring an uncertainty assessment; the GHG Protocol provides optional guidance.

Key Differences That Matter in Practice

While alignment is significant, the practical differences determine which framework serves a specific reporting need more effectively.

Prescriptiveness vs. Flexibility

The GHG Protocol tells you exactly how to categorize your emissions, which boundary approach to use, and how to handle specific scenarios. This is helpful for first-time reporters who want a step-by-step guide. ISO 14064-1 gives you an outcome specification — it describes what your inventory must achieve but lets you choose how. This works well for mature reporters who need to accommodate complex organizational structures.

Scope 2 Dual Reporting

Since the 2015 Scope 2 Guidance, the GHG Protocol requires organizations to report Scope 2 emissions using both the location-based method (grid-average emission factors) and the market-based method (contractual instruments like Renewable Energy Certificates, Guarantees of Origin, or power purchase agreements). ISO 14064-1:2018 requires one method and encourages dual reporting but does not mandate it. Organizations that have invested in renewable energy procurement may find the GHG Protocol's dual-reporting requirement more burdensome but also more transparent.

Verification Design

ISO 14064-1 was designed as a pair with ISO 14064-3 (verification). The requirements are written in "shall" language — normative and auditable. The GHG Protocol was designed primarily for reporting, and while it expects third-party verification to follow recognized standards, it does not itself specify verification criteria. In practice, verification bodies often use ISO 14064-1 as the criteria document even when the underlying inventory was prepared to the GHG Protocol.

Indirect Emission Granularity

ISO 14064-1's six-category model provides a more structured breakdown of indirect emissions compared to the GHG Protocol's umbrella "Scope 3" category. However, the GHG Protocol's Scope 3 Standard then subdivides Scope 3 into 15 categories, which offers even more granularity. The mapping between ISO 14064-1's Categories 3–6 and the GHG Protocol's 15 Scope 3 categories is not one-to-one; some GHG Protocol categories span multiple ISO categories and vice versa.

Which to Use for CDP, GRI, ISSB, and Regulatory Schemes

Organizations rarely have the luxury of choosing a single reporting destination. In practice, the same inventory may need to satisfy multiple frameworks, investors, and regulators simultaneously.

CDP (formerly Carbon Disclosure Project)

CDP's climate change questionnaire is explicitly structured around the GHG Protocol. Questions reference Scope 1, 2, and 3 directly, and the scoring methodology awards higher marks for completeness of Scope 3 reporting. CDP accepts inventories prepared to ISO 14064-1 but expects the reporter to map results back to Scope 1, 2, and 3. Importantly, CDP's scoring methodology awards bonus marks for third-party verification — and ISO 14064-3 is the most commonly used verification standard, which creates a natural bridge between the two frameworks.

GRI 305: Emissions

GRI 305 (2016) explicitly references both the GHG Protocol and ISO 14064-1 as acceptable methodologies. Disclosures 305-1 (Scope 1), 305-2 (Scope 2), and 305-3 (Scope 3) use GHG Protocol terminology but note that "alternatively, ISO 14064-1 may be used." Organizations reporting under GRI can freely use either framework — or both — as long as they disclose their methodology.

ISSB/IFRS S2

IFRS S2 Climate-related Disclosures, issued by the International Sustainability Standards Board (ISSB), requires entities to disclose Scope 1, 2, and 3 emissions. The standard explicitly references the GHG Protocol Corporate Standard as the measurement basis. However, jurisdictional guidance (e.g., for the EU's ESRS integration) may accept ISO 14064-1 inventories with a reconciliation to Scope categories. Organizations in jurisdictions adopting ISSB should prepare their primary inventory using GHG Protocol scope language while maintaining ISO 14064-1 documentation for verification purposes.

Regulatory Schemes

Regulatory emissions trading schemes typically have their own quantification rules (called Monitoring, Reporting, and Verification or MRV rules) that draw on both frameworks. For example:

• EU Emissions Trading System (EU ETS): Uses its own Monitoring and Reporting Regulation (MRR) based on ISO 14064-1 principles but with scheme-specific requirements. Verification follows EU Accreditation and Verification Regulation (AVR) aligned with ISO 14064-3.
• California Cap-and-Trade: References the GHG Protocol for corporate-level reporting but has its own mandatory reporting regulation (MRR) for covered entities.
• EU CBAM (Carbon Border Adjustment Mechanism): Requires importers to report embedded emissions in certain goods. The methodology draws on ISO 14064-1 principles and EU ETS MRR methods.

Dual Compliance Approach

Given the overlapping requirements of multiple disclosure frameworks, a growing number of organizations are building their GHG inventories to satisfy both the GHG Protocol and ISO 14064-1 simultaneously. This dual-compliance approach avoids duplication and ensures the inventory can serve any reporting need.

Step 1: Use GHG Protocol as the Accounting Backbone

Start with the GHG Protocol Corporate Standard because most reporting destinations (CDP, GRI, ISSB) expect Scope 1, 2, and 3 language. Apply the GHG Protocol's guidance on boundary-setting, quantification, and Scope 2 dual reporting.

Step 2: Structure Documentation to ISO 14064-1 Requirements

Ensure your GHG inventory report meets all ISO 14064-1 reporting requirements. This includes documenting the organizational boundary approach and justification, the criteria for significance of indirect emission sources, quantification methodologies and emission factors for each source, an uncertainty assessment, and a base-year recalculation policy.

Step 3: Create a Mapping Table

Include a reconciliation table in your inventory report that maps each emission source from GHG Protocol scopes to ISO 14064-1 categories. This table demonstrates equivalence and makes verification against either framework straightforward.

Step 4: Verify Against ISO 14064-1

Engage a verification body to provide an assurance statement against ISO 14064-1:2018. Because the inventory also conforms to the GHG Protocol, the resulting verification statement can reference both frameworks. This satisfies CDP's verification requirements, GRI's expectations, and any regulatory scheme that accepts ISO 14064-3 verification.

Practical Mapping: GHG Protocol Scopes to ISO 14064-1 Categories

The following table provides a practical mapping between the two classification systems. Note that the mapping is not always one-to-one because the frameworks use different organizing principles for indirect emissions.

This mapping should be included in your GHG inventory report as an appendix. It allows verifiers, reporting frameworks, and stakeholders to trace any emission source from one classification system to the other.

Choosing the Right Framework for Your Organization

The right choice depends on your primary reporting obligations, organizational complexity, and whether you intend to obtain independent verification.

Choose GHG Protocol as Your Primary Framework When:

• You report primarily to CDP, GRI, ISSB, or TCFD-aligned investors
• Your stakeholders use Scope 1, 2, 3 terminology
• You are a first-time reporter and need prescriptive step-by-step guidance
• You have committed to science-based targets through SBTi
• Your industry has GHG Protocol sector supplements

Choose ISO 14064-1 as Your Primary Framework When:

• You operate in jurisdictions that mandate ISO-aligned verification (EU ETS, CBAM)
• Your organizational structure does not fit neatly into the GHG Protocol's three boundary approaches
• You are a government entity, municipality, or non-corporate organization
• Third-party verification to ISO 14064-3 is a primary objective
• You already hold ISO 14001 certification and want to integrate GHG management into your environmental management system

Choose Dual Compliance When:

• You report to both voluntary frameworks (CDP, GRI) and regulatory schemes (EU ETS, CBAM)
• You want a single inventory that serves all stakeholders
• You operate internationally and face multiple jurisdictional requirements
• You are subject to mandatory assurance requirements under CSRD or ISSB adoption

The question is no longer "GHG Protocol or ISO 14064-1?" but rather "how do I build an inventory that satisfies both?" Organizations that treat these frameworks as complementary rather than competing will save time, reduce duplication, and produce more credible disclosures.

Frequently Asked Questions