The GHG Protocol, Open-Sourced

Introducing the GHGP Corporate Standard Guardian Policy (V3) - an open-source implementation of the world's most-used carbon accounting standard, ready for corporate disclosure in 2026 and beyond.

Corporate carbon accounting is in the middle of a once-in-a-generation shift. For two decades, the GHG Protocol Corporate Standard has been the foundation of how companies measure their emissions and is used by 97% of S&P 500 companies responding to CDP, embedded in CDP, SBTi, TCFD, and now in the new wave of mandatory disclosure regimes coming into force across the world's largest markets.

And yet, until now, the standard itself has only ever existed as a PDF. Every company that implements it does so in its own way, in spreadsheets, in bespoke internal systems, or inside closed SaaS platforms whose methodologies aren't independently inspectable. The result is a discipline where the same underlying standard produces hundreds of incompatible implementations, and where the data that increasingly drives regulatory disclosure, investor decisions, and supply-chain contracts often cannot be independently verified.

Today, that changes. We're announcing the release of the GHGP Corporate Standard Guardian Policy (V3): the first open-source, end-to-end digital implementation of the GHG Protocol Corporate Standard, available now for any organization to deploy.

Why this matters now

Climate disclosure is moving from voluntary reporting to mandatory, audited filings, and the timeline is short.

California's Climate Corporate Data Accountability Act (SB-253) requires companies with over $1 billion in revenue doing business in the state to publicly disclose Scope 1 and 2 emissions beginning in 2026, with Scope 3 following in 2027. The European Union's Corporate Sustainability Reporting Directive (CSRD) is already in force for large companies, with assurance requirements that escalate over the coming years. Customers across every major industry, from retail to manufacturing to financial services, are pushing carbon accounting requirements down their supply chains. And the pull is just as strong: over 10,000 companies, representing roughly 40% of global market capitalization, have now committed to science-based emissions targets through the SBTi, every one of them needing a defensible GHG inventory to track against.

What all of these regimes share is an expectation that emissions data must be measured with the same rigor as financial data: auditable, traceable, comparable, and produced on a regular reporting cadence. Sustainability teams that historically pulled numbers together once a year for a CSR report are now being asked to produce data that an external auditor will sign off on and a regulator may examine.

Most of the tools companies rely on today were not built for that bar. Spreadsheets cannot be assured at scale. Closed SaaS platforms produce numbers but rarely produce the evidence chain auditors need to verify them. And as the standard itself continues to evolve, the Land Sector and Removals Standard is now part of the Corporate Suite, Scope 2 guidance is under active revision, sector-specific guidance keeps proliferating, closed platforms struggle to keep pace.

What the GHGP Corporate Standard (V3) provides

The policy, is a complete Hedera Guardian based digital implementation of the GHG Protocol Corporate Standard, including the Scope 2 Guidance. It is open source, configurable, and built on Hedera Guardian, a policy engine designed specifically for environmental data workflows. Concretely, it provides everything an organization needs to produce a defensible GHG inventory:

• A configurable data model that mirrors how organizations actually structure themselves, entities, business units, facilities, assets, and emission sources, aligned with the corporate hierarchy reflected in financial reporting.
• Built-in emission factors and calculation tools covering Scope 1, Scope 2 (including the Scope 2 Guidance), and Scope 3 Category 1 (purchased goods and services). Secondary data libraries include the EPA GHG Emission Factors Hub, EPA eGRID Subregion Rates, Green-e Residual Mix Emissions Rates, IPCC AR5 global warming potentials, and the UK government's Defra emission factors, covering stationary combustion, mobile combustion, purchased electricity, fugitive emissions, and value-chain inputs.
• Product Carbon Footprint (PCF) support aligned with the WBCSD PACT Methodology Version 3 (formerly the Pathfinder Framework). PCFs produced through the policy are publishable and referenceable by supply chain partners, enabling companies to share verified product-level emissions data with customers and to use suppliers' PCFs to sharpen their own Scope 3 calculations. This is the practical mechanism by which Scope 3 disclosure under SB-253 (2027) and CSRD becomes tractable.
• Flexible MRV ingestion. Activity data can be entered manually, ingested via API from existing ERP, EMS, and facility systems, or streamed from IoT meters. Data is validated on ingest, so problems surface before they corrupt the inventory.
• Verifiable credentials by default. Every input, calculation, and output is captured as a tamper-evident, cryptographically signed record anchored on the Hedera network. When an auditor asks where a number came from, the answer is a verifiable chain back to the source data, not a screenshot from a dashboard.
• Optional third-party verification workflows for organizations engaging an Assurance Provider, structured to align with how the GHG Protocol envisions assurance.
• Tokenized emissions outputs (1 Carbon Emission Token = 1 metric ton CO₂e) with full provenance back to the source data, useful for intercompany allocation, internal accounting, and downstream supply-chain disclosure.

Because the policy is open source and runs on a configurable engine, organizations can extend it: add custom emission source categories, wire in jurisdictional variations as regulations evolve, and integrate sector-specific methodologies as the GHG Protocol's Corporate Suite continues to expand.

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How to use it

The policy is available now in the Hashgraph Guardian repository under the Methodology Library. Organizations evaluating it can follow a pragmatic path:

• Stand it up in a sandbox. Guardian ships with a dry-run mode designed for policy evaluation. Deploy it in your own environment, self-hosted, managed, or hybrid, and load the GHGP Corporate Standard policy from the Methodology Library. A short walkthrough of the policy in action is available at https://youtu.be/KMvClODQQN8.
• Model one business unit end-to-end. Configure your organizational structure, connect a representative emission source (a facility's electricity usage is a natural starting point), and run a complete inventory against last year's reported numbers to validate the calculations.
• Connect a live data source. Wire in activity data via API from your ERP or facility systems, or stream it from an IoT meter. This validates the ingest layer against your real operational data and demonstrates the continuous-inventory model.
• Walk the audit trail. Take the verifiable credentials produced by the policy to your internal audit team and your external assurance provider. The evidence chain is structured and queryable in ways that significantly reduce the sampling burden of traditional GHG verification.
• Extend where you need to. Add sector-specific calculation tools, jurisdictional emission factors, or custom source categories. Contribute improvements back to the open-source project so the wider corporate community benefits, and so the methodology stays aligned with how the GHG Protocol itself evolves.

Implementation partners are available for organizations that prefer managed deployments, training, or assistance with the integration work. But the policy, the methodology, and the data your organization generates remain yours, under your control, in a standard anyone can inspect.

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The wider picture

Climate disclosure is on the same trajectory financial reporting traveled twenty years ago: from narrative documents to structured, audited, comparable data. The companies that will be in the strongest position over the next decade are the ones whose data infrastructure can produce verifiable, audit-ready emissions information as a matter of routine, not as an annual scramble.

The GHGP Corporate Standard Guardian Policy (V3) is a foundational piece of that infrastructure. It is part of a broader Methodology Library on Guardian that already includes implementations from Verra, Gold Standard, Clean Development Mechanism, Global Carbon Council, iREC, and others, the same platform that handles your corporate inventory today can handle project-level methodologies, REC tracking, and product footprints as your needs grow.

The standard is open. The implementation is open. The data is yours. Explore the policy in the Hashgraph Guardian repository, and reach out to the Climission or Hashgraph team if you'd like to talk through how to put it to work in your organization.

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Data attribution: The GHGP Corporate Standard Guardian Policy (V3) incorporates emission factors and methodological references from the U.S. EPA (GHG Emission Factors Hub, eGRID), Green-e (Residual Mix Emissions Rates), the IPCC (AR5 Global Warming Potentials, used with permission), the World Business Council for Sustainable Development (PACT Methodology Version 3, Pathfinder Framework v2 Data Quality Indicators), and the UK Department for Environment, Food and Rural Affairs (Defra emission factors, © Crown copyright).

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