GHG Protocol vs ISO 14064: Key Differences Explained

Quick Comparison

What is the GHG Protocol?

The Greenhouse Gas Protocol, developed by the World Resources Institute (WRI) and the World Business Council for Sustainable Development (WBCSD), is the most widely used greenhouse gas accounting framework globally. First published in 2001, it comprises several standards: the Corporate Accounting and Reporting Standard, the Corporate Value Chain (Scope 3) Standard, the Scope 2 Guidance, and the Product Life Cycle Standard.

The GHG Protocol introduced the three-scope framework that has become universal in corporate emissions reporting. Scope 1 covers direct emissions from owned or controlled sources. Scope 2 covers indirect emissions from purchased electricity, heat, and steam. Scope 3 covers all other indirect emissions across the value chain—purchased goods, transportation, employee commuting, use of sold products, and more across 15 defined categories.

In 2023, 97% of S&P 500 companies that disclosed to CDP used the GHG Protocol, according to the GHG Protocol. It is referenced by CDP (through which more than 22,100 companies disclosed in 2025), the SBTi, the ISSB's IFRS S2, the EU's Corporate Sustainability Reporting Directive, California's SB 253, and many national reporting programs. The protocol is freely available, extensively documented, and supported by calculation tools, sector guidance, and a global community of practitioners.

What is ISO 14064?

ISO 14064 is an international standard published by the International Organization for Standardization, built on three core parts. ISO 14064-1 specifies principles and requirements for the quantification and reporting of GHG emissions and removals at the organization level. ISO 14064-2 covers GHG projects (quantifying emission reductions from specific initiatives). ISO 14064-3 sets requirements and guidance for the validation and verification of GHG statements. Two guidance documents have since joined the series: ISO/TS 14064-4 (2025) on applying Part 1 and ISO 14064-5 (2026) on verifying and validating remotely.

First published in 2006, with Part 1 revised in 2018 and Parts 2 and 3 in 2019, ISO 14064 provides a structured framework compatible with the GHG Protocol but with some differences in terminology and approach. Where the GHG Protocol uses "Scope 1, 2, 3," ISO 14064-1:2018 uses "direct emissions" and "indirect emissions" categorized by type (energy indirect, transport indirect, product-related indirect, and other indirect).

ISO 14064 carries the weight of the ISO brand—recognized by regulators, certification bodies, and procurement teams worldwide. Organizations can obtain third-party certification of their GHG inventory against ISO 14064-1, providing a formal assurance credential. This is particularly valued in jurisdictions and industries where ISO management system certifications (ISO 9001, ISO 14001) are standard practice.

Key Differences

1. Origin and governance. GHG Protocol is a multi-stakeholder initiative governed by WRI and WBCSD. ISO 14064 is a formal international standard governed by ISO's consensus-based process. GHG Protocol guidance is freely available; ISO standards must be purchased (though the cost is modest).

2. Scope framework. GHG Protocol defines Scopes 1, 2, and 3 with detailed category-level guidance (15 Scope 3 categories). ISO 14064-1:2018 categorizes emissions as direct and indirect without using the "scope" terminology, though the categories map closely. GHG Protocol's scope framework has become the universal language of corporate emissions—ISO's alternative categorization is less widely recognized.

3. Scope 2 guidance. GHG Protocol's Scope 2 Guidance (2015) requires dual reporting of market-based and location-based methods—detailed, prescriptive guidance on contractual instruments, residual mix factors, and quality criteria. ISO 14064-1 addresses indirect energy emissions but with less prescriptive guidance on accounting methods.

4. Scope 3 depth. GHG Protocol's Corporate Value Chain Standard provides extensive methodology for 15 Scope 3 categories with calculation guidance, data quality scoring, and sector-specific tools. ISO 14064-1 requires indirect emission reporting but provides less granular methodological guidance for value chain emissions.

5. Verification framework. ISO 14064-3 provides a dedicated standard for verification of GHG assertions, aligned with ISO's accredited certification body infrastructure. GHG Protocol provides guidance on verification but doesn't operate its own certification program. In practice, many verification bodies use both frameworks during an assurance engagement.

6. Flexibility vs. prescription. GHG Protocol is more prescriptive—it tells you how to calculate Scope 2, which Scope 3 categories to include, and how to set organizational boundaries. ISO 14064 provides more flexibility in approach while setting performance requirements. This means GHG Protocol offers more guidance for first-time reporters; ISO offers more flexibility for mature programs.

7. Regulatory adoption. GHG Protocol is explicitly referenced by IFRS S2, CSRD (via ESRS E1), California's SB 253, CDP, SBTi, and many national programs. IFRS S2 requires it unless a regulator or stock exchange requires another method, and SB 253 and the SBTi require it outright. ISO 14064 is accepted by some programs: ESRS E1 tells companies to consider the GHG Protocol and lets them also use ISO 14064-1, and it suits organizations already in the ISO ecosystem.

Which One Do You Need?

For most companies, the GHG Protocol is the starting point. Its scope framework is universal, its guidance is detailed and freely available, and it's referenced by virtually every reporting framework and standard-setter your stakeholders care about. CDP's questionnaire, SBTi target-setting, and CSRD-aligned reporting all assume GHG Protocol conventions.

ISO 14064 adds value in specific contexts: when your organization already operates within an ISO management system ecosystem (ISO 14001, ISO 9001), when you need formal third-party certification of your GHG inventory for procurement or regulatory purposes, or when you operate in markets where ISO credentials carry particular weight.

The good news is that the two frameworks are highly compatible. An inventory prepared under GHG Protocol requirements can be verified against ISO 14064-1 with relatively modest additional work. Many organizations prepare their inventory using GHG Protocol methodology and then seek ISO 14064 verification for the assurance credential.

Can You Use Both?

Yes, and many mature organizations do. The typical approach is to use GHG Protocol as the primary accounting methodology—following its scope definitions, calculation guidance, and reporting requirements—and then engage an accredited verification body to verify the inventory against ISO 14064-1. This delivers both GHG Protocol compliance (accepted by CDP, SBTi, regulators) and ISO certification (valued by procurement teams and quality-focused stakeholders).

The 2018 revision of ISO 14064-1 improved alignment with GHG Protocol by expanding indirect emission categories to better map to Scope 3. While terminology differences remain, the substantive requirements are convergent. A well-prepared GHG inventory satisfies both frameworks with minimal duplication of effort. The two are also converging: in September 2025 ISO and the GHG Protocol announced a partnership to harmonize their standards, and they are co-developing a consolidated corporate standard that merges ISO 14064-1 with the GHG Protocol's Corporate Standard, Scope 2 Guidance, and Scope 3 Standard. Public consultation is planned for the second quarter of 2027 and publication for the fourth quarter of 2028.

For organizations subject to mandatory reporting (CSRD, California's SB 253, ISSB-based rules, national programs), the regulatory text specifies which framework to follow. CSRD references GHG Protocol scopes explicitly. SB 253 requires reporting in conformance with the GHG Protocol, and IFRS S2 requires it unless a regulator or exchange requires another method. In practice, using GHG Protocol with ISO 14064 verification covers most needs, though mandatory regimes such as the CSRD set their own assurance requirements.

Council Fire's Perspective

We recommend GHG Protocol as the default accounting framework for every client. It's the lingua franca of corporate carbon accounting, and deviating from it creates unnecessary friction with stakeholders, frameworks, and reporting platforms. ISO 14064 is a valuable complement for organizations that need formal certification—but it's an addition, not an alternative.

Where we see organizations stumble is in over-investing in framework selection and under-investing in data quality. Whether you follow GHG Protocol or ISO 14064, your inventory is only as good as your activity data, emission factors, and boundary definitions. We help clients get the fundamentals right first, then layer on the assurance and certification that builds stakeholder confidence.

Frequently Asked Questions

Do I need to choose between GHG Protocol and ISO 14064?

No. They're compatible and many organizations use both—GHG Protocol for methodology and reporting, ISO 14064 for third-party verification and certification. Using both provides the most comprehensive credibility across different stakeholder groups.

Is one framework more rigorous than the other?

Neither is inherently more rigorous. GHG Protocol provides more detailed calculation guidance (particularly for Scope 2 and Scope 3). ISO 14064 provides a more structured verification framework. Rigor depends on implementation quality, not framework choice.

Which framework does CDP require?

CDP's climate questions (part of a single integrated questionnaire since 2024) are designed around GHG Protocol conventions—Scope 1, 2, and 3 with GHG Protocol category definitions. Companies using ISO 14064 can still respond to CDP but may need to map their categories to GHG Protocol scopes for reporting purposes.

How much does ISO 14064 verification cost?

Costs vary by organization size and complexity: the number of sites, the level of assurance (limited or reasonable), and whether Scope 3 is included all drive the fee. Large, complex organizations with global operations and extensive Scope 3 inventories pay considerably more than mid-sized companies with straightforward operations. Get quotes from several accredited verification bodies; costs often fall after the initial baseline year.