Methodology & attribution

What the numbers are

Uncovered Carbon serves dispatch-level, generator-side combustion averages:

intensity (gCO₂/kWh) = Σ(fuel_MW × fuel_emission_factor) / Σ(fuel_MW)

computed per 5-minute dispatch interval for Australia and New Zealand, and taken directly from the source for Great Britain. “Generator-side” means the number reflects what the grid’s generators emitted to produce a kWh — it excludes transmission and distribution losses.

Australia — NSW, QLD, VIC, SA, TAS

Five-minute dispatch readings (SCADA megawatts per generating unit) from AEMO’s NEMWeb, joined against AEMO’s CDEII per-generator emission factors. Every generating unit’s output is weighted by its own factor — the state figure is the generation-weighted average. Readings are calculation_method: computed-from-mix, data_quality: actual, and status: final on arrival.

Stated limitation: dispatch feeds see the grid, not behind-the-meter rooftop solar. On high-rooftop-solar afternoons (South Australia especially), true consumption intensity is lower than the dispatch average.

New Zealand

Two tiers, one lifecycle:

• Live (5-minute, provisional): the Electricity Authority’s Real-Time Dispatch feed reports megawatts per point of connection, without fuel types. We join each generating point of connection against a registry built from the EA’s monthly settlement data, then weight by Ministry for the Environment emission factors. Tagged data_quality: estimated.
• Settled (final): when the EA publishes final metered generation (roughly 2–4 weeks later), those hours are recomputed from actuals and upgraded in place. Readings only ever move forward — provisional → final, never back.

Great Britain

NESO’s Carbon Intensity API publishes half-hourly intensity directly; we store and serve it as-is (calculation_method: direct), with NESO’s own forecast-to-actual settlement reflected in the reading status.

The audit trail

Every reading carries the fields an assurance process asks about:

• data_quality — actual (metered/dispatch) or estimated (derived registry).
• calculation_method — direct (source-published) or computed-from-mix (ours).
• status — provisional → interim → final; upgrades are monotonic, a final value never regresses.
• coverage_pct — generating units we could not map to a factor are excluded and disclosed, never guessed.
• methodology_version and emission_factor_version — every reading pins the method and the exact factor-table vintage that produced it, so a number served today can be reproduced and defended later.

When to use these numbers — and when not to

Use Uncovered Carbon for: sub-hourly and real-time carbon analysis, load-shifting and demand response, 24/7 carbon-free-energy and hourly-matching calculations (SBTi Net-Zero v2), internal ESG dashboards, and operational decisions.

Do not use these figures as statutory scope-2 emission factors. They are not equivalent to a jurisdictional scope-2 residual factor. For statutory scope-2 reporting under NGER (Australia), use the AEMO-published scope 2 state factor (NGA Table 1) per the NGER methodology. For statutory reporting in New Zealand, use the MfE annual grid emission factor (Table 9) per the MfE Detailed Guide. Those published factors include transmission-and-distribution losses and specific regulatory allocation rules; Uncovered Carbon figures do not. Using them in place of statutory factors risks double-counting or under-reporting.

Change policy

Emission-factor tables refresh on their publishers’ cadence (AEMO republishes CDEII weekly; New Zealand factors are re-seeded annually). When a factor table or registry is updated, affected historical readings may be recomputed — the version fields change with them, so downstream consumers can detect it. The methodology itself is versioned; breaking method changes get a new methodology_version.

Attribution & licensing

Uncovered Carbon is built on public data published by the grid operators and agencies below. All values we serve are derived from — and modify — this source material (we compute, join, aggregate and re-serve it). We credit, with thanks:

Australia — AEMO

Dispatch data and the CDEII emission-factor series are AEMO Material, used under AEMO’s general permission, which requires accurate and appropriate attribution of the relevant AEMO Material and AEMO as its author. See AEMO copyright permissions.

Australia — DCCEEW emission factors

National emission factors are drawn from:

DCCEEW 2024, Australian National Greenhouse Accounts Factors, Department of Climate Change, Energy, the Environment and Water, Canberra, August. Licensed CC BY 4.0.

New Zealand — Electricity Authority

Real-time dispatch and settlement generation data:

www.emi.ea.govt.nz provided by the Electricity Authority (New Zealand) — licensed CC BY 4.0. See the EA’s copyright & disclaimer and EMI legal information. Values we serve are derived from this material.

New Zealand — Ministry for the Environment

New Zealand fuel emission factors are drawn from the Ministry for the Environment’s published measuring-emissions guidance (Creative Commons Attribution). We credit the Ministry for the Environment.

Great Britain — NESO

Carbon intensity data from the NESO Carbon Intensity API, licensed CC BY 4.0. We credit NESO as the source; values we serve may be reformatted and aggregated from the original.

Questions about any of this — methodology, licensing, or fitness for your use case: sales@uncoveredcarbon.com.