Australia's National Greenhouse Accounts Factors are the official emission conversion rates used to calculate Scope 1 and Scope 2 greenhouse gas emissions under the NGER Act. Published annually by the Department of Climate Change, Energy, the Environment and Water, they are the authoritative source for turning energy consumption data into a kilogram of CO2 equivalent.
For AASB S2 reporting, they are not optional. They are the source of record.
Most sustainability teams know this. The part that is catching people out is not the factors themselves. It is the audit trail.
What state-by-state variation actually means for your disclosure
Electricity emission factors in Australia vary significantly depending on the state grid. Queensland and Victoria have materially different factors. South Australia, with its high renewable penetration, sits lower again. The difference between using the right state factor and the wrong one is not a rounding error. It can change your Scope 2 number by a factor of three or four.
Under AASB S2, a material misstatement in a climate disclosure carries the same consequences as a material misstatement in a financial disclosure. Directors sign off on these numbers. External assurers are required to test them.
If the wrong factor was applied because the sustainability team used last year's spreadsheet, or used the national average instead of the state-specific figure, that is a finding.
The version control problem nobody talks about
DCCEEW publishes new NGA Factors approximately once a year. The 2025 factors are not identical to the 2024 factors. For most fuel types and grid regions the changes are small. For some they are not.
Entities preparing multi-year disclosures need to apply the factor that was current for each reporting period, not the current one. That means keeping version history, not just the latest file.
Here is what that looks like in practice if you are sourcing NGA Factors manually. You download a spreadsheet from the DCCEEW website. You paste the relevant figures into your emissions model. Six months later your external assurer asks which version of the factors you used. You look at the spreadsheet. There is no version reference in the file. There is no record of when you downloaded it. There is no way to confirm it was the version that was current at the time of your calculation.
This is not an edge case. It is the default outcome of a manual process.
What external assurers are actually checking
For AASB S2 limited or reasonable assurance, the emission factor question typically goes like this.
The assurer asks for the emission factor used in a Scope 1 or Scope 2 calculation. You provide the figure. They ask for the source. You reference the NGA Factors spreadsheet. They ask which publication year. You tell them. They ask how you can confirm it was the version in effect at the time of the calculation. This is where most manual processes break down.
A defensible answer has three components. The publication version and date of the NGA Factors used. Evidence that this version was current at the time the factor was applied. A documented, reproducible process for obtaining and applying the factor that a third party could follow and verify.
A spreadsheet download does not give you the second or third of those things.
What a governed API provides
The Tech Compass NGA Factors API serves the official DCCEEW emission factors with three things attached to every response.
The publication year and DCCEEW source reference for the factor being returned. An access timestamp showing when the factor was retrieved. A request ID that links to an immutable audit log entry, which records the call before the response is returned.
When your assurer asks how you obtained the factor and whether it was current at the time of use, the answer is a single API call log entry. The lineage is built into the process, not reconstructed after the fact.
The factors themselves are the same figures published by DCCEEW. We are not producing new data. We are providing the infrastructure that makes the data auditable in a production environment.
Who this is for
The NGA Factors API is useful in two scenarios.
The first is direct AASB S2 reporting. If your organisation is calculating Scope 1 and Scope 2 emissions and needs an auditable source for the conversion factors, this gives you a process your external assurer can follow and verify.
The second is advisory and platform contexts. Sustainability consultants and software vendors who are building AASB S2 reporting tools for clients need an auditable data source underneath their calculations. Using a governed API with lineage built in means the audit trail requirement is met at the data layer, not patched on afterwards.
Group 2 entities have six weeks
AASB S2 Group 2 mandatory filing begins in July 2026. Group 2 covers approximately 3,000 entities including large proprietary companies, foreign-controlled companies above the threshold, and additional listed entities not captured in Group 1.
If your current process for sourcing NGA Factors cannot produce an audit trail, that gap does not resolve itself by filing time.
The Tech Compass NGA Factors API is available now. Free tier covers 10,000 calls per month with no credit card required. Documentation and a compliance pack covering data lineage and vendor questionnaire responses are available at techcompass.com.au.
NGA Factors API
Free tier available now. 10,000 calls per month, no credit card required.
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