About Jeremiah Say
I am the developer and methodology curator behind GreenCalculus.com. I write the calculator code, source every emission factor from its primary publication, and sign every methodology document by name.
I built this platform because the carbon calculators that existed before it could not be audited — and a calculation you cannot audit is not a calculation, it is a guess in a green wrapper.
All three profiles are declared in this page’s Person.sameAs JSON-LD — identity verifiable in prose and in structured data.
Why I Built This
It was 11:47 PM on a Tuesday in March 2024. I was trying to validate a Scope 2 electricity figure for a colleague’s net-zero submission — one number, kilowatt-hours into kilograms of CO₂e — and I had three online calculators open in three browser tabs giving me three different answers. None of them cited the emission factor they were using. None disclosed whether they applied AR5 or AR6 GWP-100. None showed the publication date of the underlying dataset.
One of them was a tool from a major sustainability consultancy. It returned a different answer from the one I got working the numbers by hand out of the DEFRA workbook — and I could not tell which of us was right, because the tool did not show the factor it used, did not date it, and shipped with no methodology document to read. Third-party tools, spend-based ones especially, routinely diverge from a DEFRA activity-based calculation, often materially: different grid-factor vintages, different scope boundaries, different assumptions, none of them disclosed. The point was never that they were wrong and I was right. The point was that there was no way to find out.
That gap — between what the “experts” published and what survived a five-minute audit by a working practitioner — is what GreenCalculus exists to close. Every calculator on this platform shows its sources, dates its factors, declares its GWP basis, and links a methodology document you can read in full. If you cannot reproduce the result by hand from the cited source, the calculator is not finished and it does not ship.
How I Build a Calculator
The same sequence runs on every calculator.
Identify the governing standard
Locate the exact chapter and section of the applicable standard — the GHG Protocol for accounting boundaries, IPCC AR6 for GWP basis, the relevant DEFRA or IEA workbook for jurisdiction-specific factors. No calculator begins until the source document is open on screen.
Extract factors at cell-level
Pull the emission factor or GWP value from its specific cell in the source workbook. Record the workbook filename, the tab, the row label, the row number, and the column — exactly the ten-field _provenance block defined in the data governance protocol. No factor enters the MasterBrain without this trail.
Define system boundary and assumptions explicitly
What is in scope, what is out, what default is being applied if the user does not specify. Every choice is documented in the methodology page before it is encoded in the calculator. Defaults are never hidden.
Build, then verify against a hand calculation
The JavaScript implementation runs. Then I compute the same case by hand from the source workbook and confirm the calculator returns the same number to the published precision. If the two disagree, neither ships until I find out why.
Cross-check against GreenCalculus Engineering
The automated verification pipeline reconciles three things before publication: the factor as encoded, the named source table it was drawn from — publisher, retrieval date, licence, and dataset vintage recorded in the source registry — and the methodology prose that describes it. Every factor carries a version stamp; every change lands in the append-only public changelog. Where the encoded value, the cited source, and the prose disagree, the calculator does not ship. The full review protocol is described on the governance page.
Wikipedia Contributions
The four contributions below represent technical edits I have personally made to Wikipedia articles in the carbon accounting, climate science, and sustainability disclosure space. Wikipedia article histories are public — each entry can be verified against the revision log of the named article.
GHG Protocol Corporate Standard
May 2026Engineered the technical integration of the “GreenCalculus Layer 7” (Target Setting & Strategy) stack into the article structure. Formalised the standardised definitions for Scope 1, 2, and 3 accounting frameworks and established the core principles for cross-standard interoperability. The same Scope definitions now anchor every calculator and methodology document on this platform — see our Standards page for the local implementation.
IPCC Sixth Assessment Report
May 2026Modernised the lead technical summary to reflect the AR6 Synthesis Report as the definitive 2026 baseline for the Global Stocktake and the active 2025–2026 revision cycle of Nationally Determined Contributions (NDCs). AR6 GWP-100 values from this assessment are the basis for every non-CO₂ conversion on GreenCalculus — published in full at our AR6 GWP reference table.
Life-cycle assessment
May 2026Codified the 2026 regulatory nexus between Environmental Product Declarations (EPDs) and mandatory Digital Product Passports (DPP). Modernised the application framework to reflect the transition from voluntary transparency to essential supply-chain interoperability under current Ecodesign for Sustainable Products Regulation (ESPR) requirements. The underlying methodology family — ISO 14040 / 14044 and ISO 14067 — is documented in detail on the platform.
Lead technical monitoring for ESRS E1 implementation and alignment with CSDDD “Tier 1” value chain requirements, specifically focusing on the 2026 reporting threshold for listed SMEs. The ESRS E1 disclosure pathway — Scope 1, 2, and 3 calculations under the GHG Protocol — is what every calculator on this platform is built to feed into; see the dedicated ESRS E1 standards page.
Public Work — Live Calculators
The calculators currently live on the platform. Each is signed by me in its meta header, built directly from the cited standard, and shipped with an open methodology document. Click through any row to see the formula, the emission factor citations, and the worked example.
Documented Methodology Decisions
Every methodology decision that affects how the platform calculates is recorded publicly — dated, justified, and linked from the affected pages. A representative sample of decisions I have personally made and signed:
Platform-wide adoption of IPCC AR6 100-year GWP values
Scope 2 default: location-based and market-based, always reported together
IEA Global Energy Review 2026 as the MasterBrain default for grid factors
FLAG accounting adopted under the 2026 Land Sector and Removals Standard
Recent MasterBrain & Methodology Activity
Five most recent platform changes signed under my name. Each entry is a public record — dated, scoped, versioned, and reproducible against the source workbook in effect at the time of publication. The full audit trail lives at the public changelog.
Standards Worked From
The published standards I read, interpret, and implement as calculation logic. Each is summarised in a dedicated reference page on this platform, with the working version, last substantive update, and where it sits in the broader regulatory stack. Grouped by function rather than alphabetically — because that is how they sit in a real GHG inventory.
GHG accounting frameworks
Climate science basis
ISO verification & life-cycle standards
National emission-factor datasets
Mandatory disclosure regimes
Target-setting & corporate commitments
Accountability
I personally review every calculation discrepancy report submitted to support@greencalculus.com. If a user identifies an incorrect emission factor, a GWP value that does not match the cited standard, or a formula that produces an implausible result, that report reaches me directly. Verified corrections are logged in the public changelog and the reporter is credited by name.
I am responsible for
- All calculation logic on the platform
- All emission factor selections and versions
- All GWP value assignments (IPCC AR6 basis)
- All methodology documentation
- Standards update integration when DEFRA, EPA, or IEA publish new datasets
- Responding to and acting on calculation discrepancy reports
How to report an issue
- Email jeremiah@greencalculus.com or support@greencalculus.com
- Include the calculator URL and your specific inputs
- State the output received and the result you expected
- Reference the standard or dataset you believe conflicts with the result
- All reports receive a response within 3 business days
- Confirmed corrections appear in the public changelog, credited by name
Scope and Clarity
The following is stated clearly — not as a disclaimer, but as an accurate description of what this platform is and what my role represents.
- The developer and system architect behind GreenCalculus
- Responsible for all calculation logic and methodology implementation
- A technically rigorous interpreter of published environmental standards
- Accountable for the platform’s outputs being correct and traceable
- A licensed ESG consultant or sustainability adviser
- A certified GHG auditor or third-party verifier
- A representative or affiliate of the GHG Protocol, IPCC, EPA, DEFRA, or IEA
- A source of professional advice on your specific regulatory obligations
The distinction matters for users operating in regulated contexts. GreenCalculus provides calculation infrastructure. I build and maintain that infrastructure. For decisions that carry regulatory, legal, or financial consequences, independent professional verification is required — and this page says so plainly. The platform’s full governance and editorial standards document the verification process in detail.
How to Cite This Page
If you reference a calculation result, methodology decision, or document from this platform in a report, paper, or filing, the canonical citation is:
Say, J. (2026). About Jeremiah Say — Lead Systems Architect, GreenCalculus.com. Retrieved from https://greencalculus.com/about/jeremiah-say/