OneCarbon · Methodology
Most GHG inventories are assembled backwards — from templates, not from emission sources. OneCarbon is One17's structured methodology for building inventories the right way: evidence first, numbers second, disclosure third.
The Problem
Organisations reach for GRI or ISSB templates before they've mapped where their emissions actually come from. The result looks complete, but the numbers aren't traceable.
Data that passed internal review fails when a third-party verifier asks for the source document behind a figure. By then, it's costly to fix.
Over-engineered platforms and dashboards that require specialist knowledge to operate — and break down the moment the person who built them leaves.
Category-level figures in the report with no documented activity data, emission factors, or methodology behind them. These don't survive even a desk review.
The OneCarbon Process
Each stage of the OneCarbon process produces a specific evidence artefact — a document, register, or record that is traceable, reviewable, and defensible under third-party verification. The process is lean by design: we work with your existing data, your existing team, and your actual reporting requirements.
What Makes OneCarbon Different
We map every emission source to a primary document before any calculation starts. There are no figures in the final inventory that can't be traced back to a source record.
The process is structured the way a third-party verifier thinks. We've been on the other side of the audit — so we build evidence systems that hold up when the questions come.
No platform to subscribe to, no dashboard to maintain, no licence fee. The methodology is delivered as a consulting engagement. Your inventory belongs to you, in formats you can use.
We work with your existing data and team. The OneCarbon process is sized to the organisation — no over-engineering, no complexity for its own sake.
A template tells you what to fill in. A methodology tells you why each number exists, what evidence supports it, and how to defend it. OneCarbon delivers the latter.
Every inventory we produce includes the documentation and procedures your team needs to update it next year — without needing to start from scratch or re-engage an adviser.
“The gap between reported figures and verifiable figures is wider than most organisations realise — until the auditor asks.”— One17 Verification Experience
What You Receive
Formal record of organisational and operational boundary decisions, including rationale for inclusion and exclusion of emission sources.
Complete register of all emission sources within scope, with data owner, source document type, and data quality classification for each.
Fully documented calculation workbook with activity data, emission factors, GWP values, and tCO₂e outputs — all traceable to source records.
Complete inventory report aligned to GHG Protocol and ISO 14064-1, structured for disclosure, customer questionnaires, or regulatory submission.
Tell us about your reporting requirements and we'll explain how the OneCarbon process applies to your organisation. No obligation, no over-engineering.
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