MasterBrain — Emission Factor Database

What MasterBrain is

MasterBrain is the open, version-controlled emission factor database that powers every calculator on GreenCalculus. It is one normalised data layer that turns an activity — litres of diesel, kWh of grid electricity, tonne-kilometres of freight, dollars of spend — into a greenhouse-gas quantity, with every value traceable to a primary citation.

It is built for the people who have to defend a number: sustainability consultants assembling client inventories, in-house corporate ESG and sustainability teams, auditors and verifiers checking provenance, academic researchers needing a citable source, and climate-tech founders building downstream tools on a stable factor layer.

The wedge is the normalisation. MasterBrain runs a single canonical schema across 146 disparate government and intergovernmental datasets, updated continuously, with every factor traceable to a primary citation — so a UK natural-gas factor and a Singapore grid factor and a US spend-based factor share one row shape, one unit convention, and one provenance model.

Free to use, free to cite, free to embed in your inventory. There is no registration, no rate limit, and no paywall on the data itself.

Live coverage

The table below is generated live from the MasterBrain database every time this page loads — it is not a static snapshot. The Status column distinguishes live families (rows currently in use by GreenCalculus calculators) from pending families (roadmap coverage with no published rows yet, surfaced here so the roadmap is visible rather than hidden).

Each Family name links to that family’s methodology page, where the source selection, normalisation, and worked examples for that family are documented in depth. The Geos column counts distinct ISO 3166-1 alpha-3 country codes appearing in the family’s canonical-row keypaths, so a value of 50 means the family carries factors keyed to fifty separate countries.

Methodology and provenance

Source selection criteria

For any taxonomy family, MasterBrain selects a source by a four-tier hierarchy, always preferring the highest applicable tier for the geography in question.

First, primary government and regulatory publishers: the US EPA, UK DESNZ / DEFRA, the EU Commission, Eurostat, the ONS, the IEA, and the IPCC. When an official factor exists for the geography, it wins.

Second, intergovernmental and multilateral sources where no single government owns the factor: IPCC working-group reports, ISO standards, the GHG Protocol, the GLEC Framework, and IATA RP 1726.

Third, peer-reviewed academic datasets — the ICE Database v3.0, EXIOBASE, and the Cambridge CBECI for crypto — used where government and intergovernmental coverage runs out.

Fourth, industry consortia such as PCAF, the Pathfinder Framework, and ASHRAE refrigerant standards, used only when no government factor exists.

Every source resolves to a registered entry in the canonical sources registry. A row cannot cite a source that is not registered — the validator blocks the release if it tries.

Normalisation rules

Source data arrives in incompatible shapes: different units, different GWP bases, different country codings, different file structures. MasterBrain normalises all of it into one canonical form before a row is accepted.

Units resolve to SI base where possible — kg, kWh, MJ, m³, tonne-km. Geographic codes become lowercase ISO 3166-1 alpha-3 inside keypaths (gbr, usa, chn, deu, ind). The global-warming-potential basis defaults to IPCC AR6 100-year in engineering mode, with AR5 100-year preserved alongside for DEFRA regulatory-mode compatibility. And every row uses the nested factor/source/scope v3 canonical shape — a single structure across all families, which keeps downstream consumption simple no matter which family a consumer is reading.

The validator pipeline

Every MasterBrain release runs through scripts/check-mb-shape.sh before merge. A release that fails any check does not ship. Three of those checks are worth understanding because they map directly to classes of silent data corruption.

CHECK 1 — outer-vs-inner key equality

Each canonical row is keyed by a dotted string — for example fuels.gbr.natural_gas.kwh_gcv — and also carries that string in an internal 'key' field. CHECK 1 enforces that the two match exactly, for every row. This catches the “row exists but lookup misses” class of bug, where a row is present in the array but unreachable because its declared key disagrees with its position. Backwards-compatibility aliases (_alias_of rows) are exempt, because their outer key intentionally differs from the canonical key they redirect to.

CHECK 2 — no integer outer keys

Canonical rows are dictionary-keyed by their dotted string. CHECK 2 blocks any row that has ended up under an integer index instead — which happens silently when a row literal is pasted as an anonymous list element rather than as a keyed dictionary entry. Such a row looks fine on inspection but is unreachable to factor lookups, so the validator refuses the release until the row is re-keyed.

Vocabulary strict-blocks

Each activity_type term carries its own strict-block defining required fields, forbidden fields, and value constraints. A gwp_value row, for instance, must have a non-null factor.gas, a factor.gwp_set matching AR4_100|AR5_100|AR6_100, and an empty factor.unit. Because vocabulary proliferation is far harder to roll back than vocabulary consolidation, existing terms are reused wherever a new term would overlap.

Versioning model

Three version tracks move in coordination.

The MasterBrain data version (GC_MB_VERSION) is date-anchored — currently v2026.59 — and bumps on row additions, value updates, and vocabulary changes. The validator version is a comment at the top of scripts/check-mb-shape.sh — semantic (e.g. v1.x) — and bumps when the vocabulary extends or a strict-block changes. The plugin version (GC_VERSION) is semantic (e.g. v6.x) and bumps on UI, schema, or shortcode changes.

A value-changing MasterBrain bump cascades: it triggers a per-page Major bump on every Calculator and Methodology page that renders the affected value, and each of those is recorded as its own entry in the changelog, one per affected page.

Update cadence

MasterBrain re-publishes on a realistic, upstream-driven schedule: weekly during active development phases (current), easing to roughly bi-weekly during stability phases. Releases are triggered by upstream publications — DEFRA’s annual June release, EPA’s annual eGRID update, IPCC working-group reports per cycle — plus GreenCalculus’s own coverage-expansion phases.

For context on cadence: ecoinvent typically issues one major release per year, DEFRA / DESNZ updates annually in June, and IPCC working-group reports cycle on six-to-eight-year intervals. MasterBrain re-publishes within days of each upstream release. Every release is recorded as an mb_release entry, visible at Recent versions below.

Standards and frameworks alignment

At a glance, here is how MasterBrain maps onto the major accounting and disclosure frameworks — each standard links to its dedicated reference page, and the detail for each follows below.

Live = families actively used by GreenCalculus calculators. Supported = MasterBrain supplies the factor layer the framework requires; some elements (e.g. investee-reported data, iXBRL tagging) sit downstream.

GHG Protocol Scopes

MasterBrain is the operational data layer beneath GHG Protocol Corporate Standard accounting — it supplies the factors; the standard supplies the accounting boundaries.

Scope 1 — direct emissions

Scope 1 covers direct emissions from owned or controlled sources, and MasterBrain serves it through four families: stationary combustion (the fuels family, see its methodology), mobile combustion (the transport family), fugitive emissions (the refrigerants family), and process emissions (the industrial-processes family). Scope 1 factor selection follows the source hierarchy directly: DEFRA for the UK, EPA for the US, and IPCC Tier 1 defaults everywhere a primary national factor is absent.

Scope 2 — location vs market-based

The GHG Protocol Scope 2 Guidance requires dual reporting: a location-based figure (the grid average for the geography, reflecting physical emissions) and a market-based figure (instrument-specific — RECs, GOs, PPAs — reflecting contractual claims). MasterBrain’s grid family ships both location_based and market_based activity-type rows wherever the source data supports the distinction, so a consumer can report both numbers from one family rather than reconciling two sources.

Scope 3 — the 15 categories

Scope 3 spans fifteen categories, and MasterBrain families map onto them as follows: Category 1 (purchased goods and services) draws on the spend_based family; Category 3 (fuel- and energy-related activities) on fuels_wtt plus transmission_distribution; Category 4 (upstream transport) and Category 9 (downstream transport) on the upstream/downstream transport rows; Category 6 (business travel) on business-travel transport rows; Category 11 (use of sold products) on the use-phase family; and Category 15 (investments) via PCAF. Category 1 is the largest by row count — 2,147 rows — thanks to the USEEIO v2.0 plus UK ONS plus Eurostat AEA+GVA spend-based integration.

ISO 14064 and ISO 14067

ISO 14064-1 governs the organisational GHG inventory, and its Clause 6.3 calls for the use of standardised emission factors from recognised sources — a requirement MasterBrain factors satisfy by construction, since every row traces to a registered primary source. ISO 14067 governs the product carbon footprint; MasterBrain supplies cradle-to-gate factors through the materials and supply_chain families, which you combine with ISO 14040/14044 life-cycle process data to assemble a full product footprint.

CDP and SBTi

The CDP Climate Change 2025 questionnaire asks, in its C5 and C6 blocks, for the emission factors used and their sources; MasterBrain’s per-row source attribution maps onto those questions directly. The SBTi Corporate Net-Zero Standard v1.2 requires the IPCC AR6 100-year GWP set for base-year recalculations, which MasterBrain ships in its gwp family. For SBTi FLAG, MasterBrain ships the GWP set plus the AFOLU global-aggregate rows the FLAG engine consumes.

TCFD and IFRS S2

The TCFD recommendations and their successor, IFRS S2 Climate-related Disclosures, both sit on a Metrics & Targets pillar that requires Scope 1, 2, and 3 quantification. MasterBrain factors are appropriate inputs to that pillar, and the per-row version stamp plus audit trail make them defensible under IFRS S2’s expectation that disclosers use established methodologies rather than ad-hoc figures.

CSRD / ESRS E1

ESRS E1 — Climate Change (Commission Delegated Regulation 2023/2772) requires gross Scope 1, 2, and 3 emissions in tonnes of CO₂e for the reporting entity. MasterBrain factors directly satisfy ESRS E1-6 (gross GHG emissions). The geographic granularity of the keypaths (gbr, deu, fra, nld, and the rest) supports the entity-level resolution ESRS E1 expects, and the iXBRL tagging requirement is met at the report-generator layer — MasterBrain’s job is to supply the underlying, citable factor values that sit beneath the tags.

Regional disclosure rules

US SEC Climate Disclosure

The US SEC Climate-Related Disclosure Rule (Final Rule, March 2024) requires Scope 1 and Scope 2 disclosure from accelerated and large accelerated filers. MasterBrain’s US grid and fuels factors trace to EPA eGRID 2023 rev2 — the SEC-cited primary source — so a US filer is citing the same authority the rule points to.

California SB 253 and SB 261

California SB 253 (the Climate Corporate Data Accountability Act, 2023) requires Scope 1, 2, and 3 disclosure from companies doing business in California with global revenue above $1B, on a CARB-set timeline; SB 261 adds a climate-related financial-risk disclosure. MasterBrain factors are SB 253-defensible because they trace to EPA and IPCC primary sources.

EU ETS, Singapore CPA, Australia Safeguard

For carbon-priced jurisdictions, MasterBrain supplies the activity-data conversion factors regulators expect under EU ETS Phase 4 (2021–2030), the Singapore Carbon Pricing Act 2018 (as amended), and the Australian Safeguard Mechanism (Crediting) Amendment Act 2023.

How to access MasterBrain

Through GreenCalculus calculators (recommended)

The primary access path is the calculator surface. Every page under GreenCalculus calculators reads MasterBrain at render time: you pick a calculator, enter activity data, and receive a result in which every number on the output panel cites the underlying factor row, its source, and the retrieval date — provenance is attached to the answer, not buried in a methodology appendix.

By Scope, the common entry points are the SC1 Stationary Combustion and SC1 Mobile Combustion calculators for direct emissions, the SC2 Electricity Location-Based calculator for purchased power, the SC3 Cat 1 Spend-Based calculator for purchased goods, and the FLAG Emissions calculator for land-sector accounting.

Each calculator page loads only the factors it needs rather than the full database envelope — a sub-10% payload for most calculators, which keeps the calculator surface fast without sacrificing provenance.

REST API

All endpoints live under the base path /wp-json/greencalculus/v1/, are public, unauthenticated, and currently unmetered. Every response carries X-GC-Version and X-GC-Updated headers (and the same values in its meta block), so a programmatic client can log exactly which database version produced a given result.

/v1/factors (paginated, v3 canonical)

This is the recommended endpoint for programmatic access. It is cursor-paginated (100 rows per page; follow meta.next_cursor) and filterable by query string on section, key_prefix, and family, and it returns the canonical v3 row shape (nested factor/source/scope).

curl "https://greencalculus.com/wp-json/greencalculus/v1/factors?section=fuels&key_prefix=fuels.gbr.natural_gas"

{
  "meta": {
    "gc_version": "2025.72", "gc_updated": "2026-06-11",
    "total": 16, "returned": 16, "offset": 0, "next_cursor": null,
    "filters": { "section": "fuels", "key_prefix": "fuels.gbr.natural_gas", "family": null }
  },
  "factors": [
    { "key": "fuels.gbr.natural_gas.kwh_gcv",
      "name": "UK Natural gas — combustion (kWh (Gross CV))",
      "section": "fuels", "activity_type": "stationary_combustion",
      "factor": { "value": 0.18296, "unit": "kg CO2e per kWh", "gas": "CO2e", "basis": "GCV", "gwp_set": "AR5_100" },
      "source": { "id": "DEFRA_2025", "cell_ref": "'Fuels'!D42", "retrieved": "2026-05-17" },
      "scope": { "ghg_protocol": "scope1", "category": "stationary_combustion" } }
    // ...
  ]
}

/v1/master-brain (legacy nested)

This endpoint returns the legacy nested v2.6 shape. It is maintained for backwards compatibility with existing client integrations that were built against the older structure; new consumers should use /v1/factors instead, which exposes the canonical shape and the filter parameters.

/v1/gwp-values (self-documenting)

This endpoint returns the IPCC AR4/AR5/AR6 100-year GWP table — 22 rows under the gwp section. The JSON is self-documenting: each entry carries the gas, the AR version, the 100-year GWP, and the source citation, so a consumer can read the table without an external key.

Direct PHP (advanced)

If you are extending the plugin itself, three memoised accessors are available: gc_mb_raw_factors() returns the full canonical-rows array, gc_mb_canonical_taxonomy_families() returns the family taxonomy map, and gc_mb_canonical_sources_registry() returns the source-id-to-description registry. Each caches per request (static $cached), so they are safe to call repeatedly within a single page load. This path is intended for plugin extensions only — third-party WordPress sites should consume the REST endpoints rather than calling PHP directly.

Compared to other emission factor databases

The honest comparison is the authority play here: evaluators and procurement teams searching for the right database are not looking for superlatives, they are looking for an accurate map of which tool does which job. Each database below is described on its own terms, with its real strengths stated, followed by the specific axis on which MasterBrain differs.

ecoinvent

ecoinvent is the most-cited life-cycle inventory database in the world — more than 15,000 unit processes, currently at v3.10 — and it underpins virtually every commercial LCA tool. Its strength is the depth of its unit-process modelling for cradle-to-gate analysis: if you are modelling a product’s supply chain at the process level, ecoinvent is the reference. The differences are scope and access. ecoinvent is licensed and paid for commercial users; MasterBrain is free. ecoinvent issues one major release per year; MasterBrain ships weekly. The two are not substitutes — ecoinvent models unit processes for LCA, while MasterBrain supplies operational factors for organisational inventories.

EPA Emission Factors Hub

The EPA Emission Factors Hub is the US EPA’s compiled emission-factor reference, refreshed annually, and it is the definitive US authority for stationary and mobile combustion and for grid electricity. Its strength is exactly that authority — for US rows, the Hub is the source MasterBrain itself inherits from. The differences are reach and format: the Hub is US-only, whereas MasterBrain integrates EPA factors for US rows and extends the same schema to 200-plus geographies; and the Hub is distributed as PDF and XLS, whereas MasterBrain exposes the same factors as programmatic JSON.

DEFRA / DESNZ

The UK Department for Energy Security and Net Zero (formerly BEIS and DEFRA) publishes the UK Government GHG Conversion Factors every June, and it is the definitive UK authority. Its strength, like the EPA Hub’s, is regulatory primacy for its geography. The difference is the same axis of reach: the DEFRA dataset is UK-only, whereas MasterBrain integrates DEFRA factors for UK rows and harmonises them into the same global schema that carries every other geography, so a multi-country inventory does not have to stitch DEFRA’s format to anyone else’s.

Climatiq

Climatiq is a commercial, API-first emission factor database with a clean REST interface and broad coverage, and the quality of its developer experience is a genuine strength for teams building software. The difference is commercial: Climatiq’s free tier is limited and rate-limited, with paid plans above it. MasterBrain offers comparable REST coverage that is currently unlimited and free.

CarbonCloud

CarbonCloud specialises in food-product carbon footprints, and within that category its depth is its strength — it is a serious tool for food and beverage companies. The difference is breadth of purpose: CarbonCloud is food-specific, whereas MasterBrain is general-purpose across all GHG Protocol scopes and sectors. For a food company, the two can be complementary; for a general corporate inventory, MasterBrain covers categories CarbonCloud does not address.

IPCC Emission Factor Database (EFDB)

The IPCC EFDB is the reference database national-inventory compilers draw on, and its strength is methodological depth — it carries the documentation and uncertainty ranges that inventory methodologists need. The difference is audience and shape: the EFDB is reference material for the people who build national inventories, whereas MasterBrain is operational data wired into a reporting workflow. They complement each other rather than compete — MasterBrain’s own IPCC-sourced rows trace back to exactly this kind of reference material.

At-a-glance comparison

Use the right database for the job. MasterBrain is purpose-built for corporate sustainability inventories under the GHG Protocol — operational, transparent, free. For LCA process modelling, pair MasterBrain (operational factors) with ecoinvent (unit processes); the database-comparison methodology sets out the criteria behind this table in full.

Sample factors — eight worked examples

The methodology above explains how a factor gets into the database; the eight examples below show what one actually looks like in use. Six are real canonical rows rendered live through the [gc_factor] shortcode, so the value stays current with the database rather than going stale in prose. Two — road freight and the FLAG land-use-change example — are version-pinned snapshots from families not yet migrated to the live V3 keyspace, and are labelled as such.

Recent versions

Every MasterBrain release is recorded automatically on deploy. Each entry below lists the version, the release date, and the changelog excerpt for that release. For per-page version history — which Calculator or Methodology page was affected by which MasterBrain bump — see the full changelog.

Every factor in MasterBrain is authored and maintained by Jeremiah Say, Lead Systems Architect and Methodology Curator at GreenCalculus, working from Singapore. His full profile, prior work, and contact details are on the author page.

The credentials that matter here are structural rather than personal: the methodology and its source code are open and inspectable, and every factor traces to a primary citation a reader can verify independently. Jeremiah also contributes the underlying methodology to the public record, including the Wikipedia articles on the GHG Protocol, IPCC AR6, life-cycle assessment, and CSRD. The release-verification process is detailed in the next section.

Verification standard

Verification is in-repo and reproducible, not a claim on a page. Two parity gates must pass before any merge, every release hands off through a recorded audit trail, and the public changelog documents the result. You can read the data-layer releases via the data-layer changelog and the plugin releases via the plugin changelog. The verification approach is consistent with ISO 14064-3, the standard for the validation and verification of GHG assertions.

Feedback and corrections

To report a correction or request a new factor or geography, use the contact channel on the author page — primary-source integration for new geographies is a roadmap item driven directly by these requests.

Frequently asked questions

Citation and licensing

How to cite MasterBrain

Cite both the version and the retrieval date — they are not optional, because the database is updated weekly and a citation without them will not reproduce.

Prose form:

Say, J. (2026). MasterBrain — The GreenCalculus Emission Factor Database (v2026.59, retrieved 2026-07-18). GreenCalculus. https://greencalculus.com/masterbrain/

BibTeX:

@misc{say2026masterbrain,
  author       = {Say, Jeremiah},
  title        = {{MasterBrain --- The GreenCalculus Emission Factor Database}},
  year         = {2026},
  version      = {2025.72},
  url          = {https://greencalculus.com/masterbrain/},
  note         = {Retrieved 2026-06-11}
}

The version and retrieved date are the load-bearing fields here. Because MasterBrain re-publishes weekly, a factor value cited today may differ from the same keypath next month — recording the version is what lets a reader reconstruct your number.

License terms

MasterBrain is released under the CC-BY-4.0 (Creative Commons Attribution 4.0 International) license. It permits commercial use, redistribution, modification, and embedding in proprietary tools, subject to attribution. Attribution means citing MasterBrain per the format above, linking back to https://greencalculus.com/masterbrain/, and indicating any modifications you made.

One transitivity point: when MasterBrain attributes a factor to an upstream source — DEFRA, EPA, IPCC, and the rest — that upstream source’s own license terms also apply. Most government sources are public-domain or open-data licensed, but verify per source for any commercial-redistribution edge case.

Historical version retention

Every released MasterBrain version is retained indefinitely. Historical versions are accessible three ways: through the mb_release records (admin-side, and exposable at /mb-release/<slug>/ URLs if published publicly in future), through the plugin’s git history in the greencalculus-mb repository, and through the deploy log (scripts/deploy-log.txt), which records every shipped version with its timestamp and commit SHA.

For reproducibility, recompute against the version cited in your inventory — do not silently re-cite an old figure against the current version, because the value may have moved.

Permitted and prohibited uses

Permitted: corporate sustainability inventories, academic research, regulatory disclosures, internal tooling, and downstream commercial products, all with attribution.

Prohibited: misrepresenting MasterBrain as your own dataset, stripping attribution, and using MasterBrain values in any way that contradicts an upstream source’s own attribution requirements. The dataset is free and open; the one thing it asks in return is honest provenance. The full author and contact details are on the author page, and the source is in the open-source plugin repository on GitHub.