COMET — Carbon Ontology for Markets, Emissions & Trade

Start Here

New to COMET? Here's the whole thing, in plain language.

An ontology is just a shared dictionary — an agreed list of terms and how they relate. COMET is that dictionary for carbon data. Right now, “one tonne of CO₂” on one platform doesn't line up with the same words on another: different units, boundaries, methods, and emission-factor vintages. COMET defines every term once, so a footprint, a certificate, or a customs declaration means the same thing everywhere.

Think of it like the metric system, but for carbon: shared units and definitions everyone can build on — so data becomes comparable, verifiable, and tradeable across industries and borders.

Below is the entire dictionary — every class, property, value, and standards mapping. Explore it as an interactive map, sort and search the full lookup, or download the whole thing as a spreadsheet.

1168

Terms

177

Classes

225

Properties

Layers

392

Standards Maps

649

CAD Trust Fields

Explore the Interactive Schema Map → Search & sort all 1168 terms ↓ Download everything (Excel .xlsx)

What COMET Does

One ontology. Every standard. Every sector.

          The standards that produce carbon data all speak different dialects. COMET is the shared language between them — and the single graph every stakeholder reads. Standards and crosswalk counts are generated live from the published alignments.
        

Shared Vocabulary

One ontology maps ISO 14067, PACT v3, GHG Protocol, CBAM, and EAC standards into interoperable classes that any platform can consume.

Seven-Layer Stack

From core identity primitives (L1) to market pricing signals (L7), each layer is independently versionable and composable with the rest.

Community Governed

Steering Committee, Technical Committee, and open Working Groups. All decisions made via public GitHub with full audit trails.

Who Benefits

Built for everyone who touches carbon data.

Industrial Buyers

Equal-footing supplier comparison

Compare supplier PCFs on equal footing. Auto-generate CBAM declarations from structured, verified data.

Carbon Verifiers

Machine-readable claims

Issue machine-readable verification claims. Replace static PDFs with trusted, queryable data objects.

Platform Vendors

Instant interoperability

npm install @comet/ontology — instant interoperability with any COMET-compliant platform.

Regulators

Proven open standard

Reference a proven open standard for CBAM, CSRD, and IRA 45V compliance frameworks.

LCA Practitioners

Universal export format

Export SimaPro and openLCA results in a universal format any downstream system can read without translation.

Financial Markets

Product-level carbon risk

Price carbon risk using verified, product-level data rather than sector averages and disclosure estimates.

Deep Dive

50 quantified use cases across 10 stakeholder groups

Interactive Sankey diagrams, sourced savings metrics, and a “My Use Case” builder that maps your data onto COMET layers.

Explore Stakeholder Benefits →

Standards Integration

One vocabulary. Every carbon data standard.

COMET provides the semantic middleware between data producers and consumers. Supply chain platforms, LCA tools, and registries produce data in proprietary formats. COMET’s JSON-LD context injection maps any payload into a shared ontology — so buyers, verifiers, regulators, and carbon markets can consume standardized, machine-readable data without translation.

WBCSD PACT v3

Complete field-by-field mapping

Every PACT v3 ProductFootprint and CarbonFootprint field maps to a COMET class via owl:equivalentClass and owl:equivalentProperty triples. Drop-in JSON-LD @context upgrades any PACT payload to semantic RDF.

EU CBAM

Declaration structure in XML & JSON

CBAM embedded emissions declarations (Reg. 2023/956) mapped to COMET classes with working XML, XSD schema fragments, and CN code coverage for steel, aluminium, cement, hydrogen, and chemicals.

CAD Trust v2.0.2

Full registry interoperability

All 13 CAD Trust tables (project, unit, verification, issuance, label, co-benefit, Article 6 ITMO) mapped into COMET namespaces. 100+ variables aligned for carbon credit registry data exchange.

GHG Protocol & ISO 14067

Scope 3 and product-level coverage

GHG Protocol Scope 3 Categories 1–15 mapped to COMET supply chain and PCF classes. ISO 14067 Section 7 required elements fully covered in L4 PCF layer.

Data Tools

Convert, validate, and export — today.

COMET ships with a complete, open-source data toolchain so you can start working with COMET-compliant data immediately. Every tool runs locally (Python CLI) or in your browser (Playground) — no accounts, no API keys, no vendor lock-in.

Ingest

4 Format Converters

Convert CSV spreadsheets, PACT v3 JSON, CBAM XML declarations, and CAD Trust registry data into COMET JSON-LD with a single command. Field-level mappings cover 44 PACT fields, all CBAM CN codes, and 13 CAD Trust tables.

Validate

JSON Schemas + CLI

Three JSON Schemas (PCF, EAC, Core) validate any COMET document against the ontology. The comet validate CLI gives structured errors with fix suggestions. Batch mode validates entire directories.

Export

3 Egress Formats

Export COMET data back to PACT v3 for WBCSD exchange, CBAM XML for EU regulatory filing, or flat CSV for spreadsheet workflows. Round-trip fidelity ensures nothing is lost in translation.

Browser

Data Playground →

Paste or upload data in any supported format and instantly convert, validate, and download COMET JSON-LD — entirely in your browser. No install required. Try it with the built-in steel, aluminium, and DAC credit examples.

CLI + Python

Command-Line Toolkit

pip install jsonschema python comet_cli.py validate my-pcf.json python comet_cli.py convert data.csv --from csv --to comet CSV templates, 6 worked examples (steel, aluminium, DAC credits, PACT, CBAM, CAD Trust), and full documentation included.

Documentation

Everything you need to build with COMET.

Start Here — 7 Plain-Language Views

How COMET Works

New to carbon data? Seven animated pictures show COMET as the under-the-hood plumbing — from the data flows to the business results — with no jargon required.

Visual Reference — 20 Data Visualizations

Visual Guide

20 MECE visualizations: seven-layer stack, standards heatmap, PACT/CBAM/CAD Trust mappings, data quality radar, contribution workflow, regulatory timeline, and market signals.

Getting Started — 8 Stakeholder Guides

How To Use COMET

Eight concrete examples showing buyers, supply chain managers, LCA practitioners, verifiers, platforms, regulators, financial markets, and credit developers how COMET solves their specific problems.

Interactive — 50 Quantified Use Cases

Stakeholder Benefits & Use Case Builder

10 stakeholders × 5 use cases with Sankey diagrams, quantified savings, and an interactive “My Use Case” builder that maps your data onto COMET layers.

Technical Specification

Data Exchange & Transport Layer

Field-by-field mappings for PACT v3, EU CBAM, and CAD Trust with working code examples in JSON-LD, XML, XSD, JSON Schema, and OWL Turtle.

Reference Dictionary — Interactive Search

Glossary & Data Dictionary

Complete class, property, and variable reference for all 7 COMET layers plus CAD Trust v2.0.2. Interactive search with layer filters and A–Z jump bar.

Interactive Visualisation — Graph, Lookup & XLSX

Schema Map & Value Explorer

Explore every class, property and individual as an interactive force graph, read the layered seven-layer schema, sort and search the full value lookup, browse 392 standards alignments — or download the complete spreadsheet of all values.

Interactive Tool — Browser-Based

Data Playground

Paste or upload CSV, PACT v3, CBAM XML, or CAD Trust data and instantly convert to COMET JSON-LD. Validate, preview, and download — no install required.

Reference Specification

Ontology Specification

The complete COMET ontology: 7-layer architecture and 20 visualization sections covering stakeholders, maturity model, namespace architecture, standards alignment, governance, and more.

Implementation Roadmap

Master Build Plan

200 expert steps across 10 MECE panels, sequenced into a 36-month roadmap from foundations to v1.0 stable. Assigned owners, dependencies, and success criteria for every step.

Presentation — Download PPTX

Stakeholder Deck

30-slide presentation covering the problem, architecture, stakeholder benefits, governance model, and roadmap. Ready for board, investor, and regulatory audiences.

New — I-REC(E) Electricity · comet-irec:

I-REC(E) Renewable Energy Certificates

The Evident I-REC Code for Electricity v1.13 and Standard Forms SF-02 / SF-04 mapped onto the stack — reusing comet-eac: for the certificate (subType IREC), comet:Site for facilities and comet-eac:RetirementEvent for redemption. New terms for the SF-04C multi-fuel co-firing allocation, the QR-verified Redemption Statement, and the anti-double-counting declarations, with SHACL and a JSON-LD converter.

New — TfS PCF Data Model · comet-tfs:

TfS PCF v3.1 (Chemicals)

All 131 fields of the Together for Sustainability PCF Data Model v3.1 (Sept 2025) mapped onto the seven-layer stack. Twelve owl:equivalentClass bridges, 24 new classes for the PACT-aligned A–H emission decomposition, mass balancing, CCU/CCS credits, data-quality (PDS + DQR), verification shares, and the Attestation of Conformance. Interoperable with WBCSD PACT and Catena-X.

New — ISO 14068-1 Extension

Carbon Neutrality (ISO 14068)

How ISO 14068-1:2023 maps onto the seven-layer stack. Eighteen owl:equivalentClass bridges to existing COMET, twenty-four new classes for Plan / Pathway / Claim / Report, and stakeholder benefits for industry, finance, verifiers, and regulators.

New — PCR Japan Extension · comet-pj:

PCR Japan / SuMPO EcoLeaf

Bilingual (Japanese/English) extension for the SuMPO EPD Japan program. 76 PCRs harvested from ecoleaf-label.jp, 85 requirements extracted, 9 new classes including SuMPOPCRDocument, a 13-concept SKOS product field taxonomy, SHACL shapes, and full 日本語 labels for all COMET core terms. Data source: PCRbase.

New — CarbonSig PCR Extension · comet-pcr:

Product Category Rules (comet-pcr)

PCR method vocabulary extending L4 (PCF): a structured, versioned PCRDocument reifying the PCRReference stub, the keystone governedByPCR link, plus CutOffRule, DeclaredModule, ReferenceServiceLife, and PEF terms. Now published in the COMET term graph (17 terms). Source: PCRbase.

New — Standards Alignment · csig:

CarbonSig Verifier Export v4

74 SKOS crosswalks mapping the CarbonSig Verifier Hub export contract (v4) onto COMET — emission factors (L2), supply-chain flows & scope 1/2/3 (L3), PCF declarations (L4), and verification status (L6) — each tagged High / Medium / Low certainty. Now part of the 392 standards-alignment crosswalks.

New — ASI Aluminium Extension · comet-asi:

Aluminium Stewardship (ASI)

Maps the aluminium-specific variables of the ASI Performance Standard V3 (Principle 5 — GHG) and Chain of Custody Standard V2 onto COMET: ASICertification, CoCClaim, production route & anode-effect metrics. 38 terms typing only the gaps — Scope 1/2/3, site and verifier identity are reused. Includes a CBAM alignment and SHACL shapes.

Explainer Video & v0.1 Deck

Materials: A Shared Carbon Language

Six-minute narrated walkthrough of COMET paired with the 14-slide v0.1 Carbon Protocol deck. Includes slide-by-slide summaries linking each visualization to the ontology layers, namespaces, and governance model.

Video — MP4 Download

COMET Explainer Video

Six-minute narrated walkthrough of the protocol — market problem, JSON-LD @context injection, the seven-layer stack, and standards interoperability. Suitable for first-conversation context with partners and regulators.

Presentation — Download PPTX

Carbon Protocol Deck (v0.1)

Fourteen slides from carbon variance and the seven-layer architecture through compliance hooks (CBAM, IRA 45V, CSRD, EN 15804), governance, the adoption flywheel, and the 2025–2028 roadmap.

Roadmap

From foundations to global infrastructure.

Phase 1 · Complete

Q1–Q2 2025

Foundations & First Adopters

Core ontology & 7-layer stack
PACT v3 full alignment (44 fields)
JSON Schema validation
CBAM declaration class
Data toolchain (CLI, converters, playground)

Phase 2 · Current

Q3 2025 – Q1 2026

Supply Chain & Verification

Full supply chain module
CAD Trust verification layer
EAC hierarchy & registry interop
Verification connector pilots

Phase 3

Q2 2026 – Q4 2026

Market Layer & Sectors

Pricing signals layer (L7)
Steel / H₂ / Chemicals / Aluminium WGs
CSRD mapping
v1.0 stable release

Phase 4

Q1 2027 – Q4 2027

Global Scale & Nature

Real-time IoT streaming
TNFD biodiversity layer
Tokenized EAC rails
AI query interface

Partner With Us

Build the carbon data infrastructure the world needs.

COMET is an open standard — but adoption requires collaboration. We are seeking founding partners from industry, platforms, verifiers, and regulators to shape the ontology, pilot integrations, and join the governance structure.

Industry

Steel, aluminium, chemicals, and cement producers piloting COMET for CBAM compliance and supply chain data exchange.

Platforms

Carbon accounting, LCA software, and supply chain platforms integrating COMET as a data exchange layer.

Verifiers

Assurance firms issuing machine-readable verification claims that flow through the COMET network.