The NGA Factors are the Australian Government’s reference set of emission factors for estimating greenhouse gas emissions outside the NGER Scheme. The Department of Climate Change, Energy, the Environment and Water (DCCEEW) publishes a revised workbook every year, and each edition supersedes the last.
Key points
- Published and revised every year by DCCEEW
- Covers Scope 1, 2 and 3 across energy, industry, waste, agriculture and land use
- Methods are based on NGER Method 1 unless stated
- Generally uses AR5 100-year global warming potentials
- Must not be used for NGER reporting
What the workbook covers
- Energy: electricity, stationary combustion of solid, gaseous and liquid fuels, and transport fuels
- Industrial processes and product use, including refrigerants and carbonates
- Waste: landfill, wastewater, incineration and biological treatment
- Agriculture and land use, land use change and forestry, added in the 2026 edition
It provides Scope 1, Scope 2 and Scope 3 factors, including location-based and market-based electricity factors. For fugitive emissions, it refers users to Chapter 3 of the NGER Measurement Determination.
How the factors are derived
DCCEEW estimates the default factors using Australia’s National Greenhouse Accounts and National Inventory Report, so company-level estimates are consistent with the national inventory. Unless stated otherwise, the methods are based on Method 1 of the NGER Measurement Determination. Factors are generally expressed in CO2-e using 100-year global warming potentials from the IPCC Fifth Assessment Report.
What they are not for
DCCEEW states that the NGA Factors must not be used to meet reporting requirements under the NGER Act 2007. NGER reports use the Measurement Determination in force for the reporting year. The Clean Energy Regulator states that Scope 3 is not reportable under NGER but that the NGA Factors can be used to estimate it.
Editions and history
The workbook is revised annually and historical editions are not revised. DCCEEW notes that a new edition does not necessarily mean past estimates must be revised, depending on their intended use. Recording which edition each figure used keeps an inventory traceable year on year.
Why it matters
For organisations reporting under several regimes, the NGA Factors usually carry Scope 3 and voluntary inventories while the Measurement Determination carries NGER. Keeping the two sources separate, and labelled, avoids the most common factor error.
References & sources
Primary regulatory documents and authoritative references underpinning this answer.