About Jeremiah Say
I am the developer and methodology curator behind GreenCalculus.com. I build the emission-factor API and the calculation engines behind it, source every emission factor from its primary publication, write the calculator code, and sign every methodology document by name.
I built this 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. The API is that same standard, made callable: if a number comes out of it, the place it came from comes out with it.
If you are integrating and something is wrong, unclear or missing, I am the person who answers. There is no support tier in between.
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.
It became an API because of who kept writing to me. Not sustainability officers looking for a calculator, but engineers building carbon accounting into someone else’s product — and every one of them was doing the same unglamorous work I had done: reading a DEFRA workbook, typing factors into a table, and then owning that table forever as publishers revised their numbers underneath it. That is not their product. It is mine. So the factors and the engines are now an API — every value returned with the exact place in the source it came from, and every result pinned to the data version it ran against, so a figure that has already been filed does not move when a publisher revises upstream.
The keyless browse endpoint is there for the same reason as the methodology pages. You should be able to check my numbers before you pay me for them, and if I ever make it hard to, that is the point at which you should stop trusting this platform.
How I Build a Calculation
The same sequence runs on every calculator and every API engine. There is no faster path for the endpoint — a number served over HTTP is easier to trust blindly than one on a page, so it gets the same five steps, not fewer.
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. Nothing begins, calculator or endpoint, until the source document is open on screen.
Extract factors at cell-level
Pull the emission factor or GWP value from the exact place the publisher put it. Record the document and that place — a workbook cell where the publisher ships a workbook, otherwise the table, the annex clause or the page — the cell-level source reference defined in the data governance protocol. No factor enters the MasterBrain without this trail, and because it is recorded as data rather than prose, it is what the API hands back: cell_ref is a field on every row, not a footnote I remembered to write.
Define system boundary and assumptions explicitly
What is in scope, what is out, what default is being applied if the caller does not specify. Every choice is documented in the methodology page before it is encoded. Defaults are never hidden — over the API they are returned in the working block with the result, so a caller who accepted a default can see which one they got.
Build, then verify against a hand calculation
The implementation runs — the browser calculator and the API engine share the same method and are checked against each other. Then I compute the same case by hand from the source workbook and confirm both return the same number to the published precision. If any two of the three disagree, none of them 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 are 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. I edit under a declared connection: my Wikipedia user page discloses that I operate GreenCalculus, per Wikipedia’s conflict-of-interest guideline.
GHG Protocol Corporate Standard
May 2026Added three sections to the article — Accounting framework (Scope 1, 2, and 3), Accounting principles, and Relationship to other standards — with every claim cited to the published standard, not to this site. The same Scope definitions anchor every calculator and methodology document on this platform — see our Standards page for the local implementation.
IPCC Sixth Assessment Report
May 2026Updated the article lead to describe the AR6 Synthesis Report as the active baseline for the Global Stocktake and the 2025–2026 revision cycle of Nationally Determined Contributions (NDCs) — a small, sourced context edit. 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 2026Updated the article’s “LCA uses” section to note the 2026 regulatory context around Digital Product Passports (DPP) and their reliance on EPD data under the Ecodesign for Sustainable Products Regulation (ESPR). The underlying methodology family — ISO 14040 / 14044 and ISO 14067 — is documented in detail on the platform.
Housekeeping edit: removed outdated maintenance tags and clarified historical context in the article. Separately, in June 2026 I drafted new articles on IFRS S1 and IFRS S2, submitted through Articles for Creation for independent editorial review — with the conflict of interest disclosed in each submission and no citations to GreenCalculus. The ESRS E1 disclosure pathway that sits alongside these regimes — 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 — What I Ship
The surfaces currently live, in the order they now matter. Each is signed by me, 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. The calculators below are the same engines with a form on the front — not a separate implementation.
pip install greencalculus·npm install greencalculusDocumented Methodology Decisions
Every methodology decision that affects how the platform calculates is recorded publicly — dated, justified, and linked from the affected pages. That now includes decisions about the API’s own contract, because a field name is a promise to somebody’s production code. A representative sample of decisions I have personally made and signed:
A factor is a canonical row, not an address
total field still counts rows including aliases, because that field is a pagination contract: change its meaning and a caller paging through the corpus silently stops early. Two different questions deserve two numbers, so canonical_total answers the second one over the API as well.The calculation engines stay open on every tier
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 recent MasterBrain and methodology 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 — whether it came from a page or from an API response. Verified corrections are logged in the public changelog and the reporter is credited by name. API and integration questions go to jeremiah@greencalculus.com and reach the same person.
I am responsible for
- All calculation logic on the platform, in the browser and over the API
- The API contract — every field name, and what changing one would break
- 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, or the endpoint and request body, plus 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
- The person who answers integration and API questions directly
- 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, factor value, or methodology decision from this platform in a report, paper, or filing, cite the page that carries the number — the calculator, methodology, data, or standards page — together with the MasterBrain data version shown on it. This profile exists so you can verify who is behind the work; it is not the page to cite.
GreenCalculus. <page title>. MasterBrain <data version shown on the page>. Retrieved <date>, from <page URL>