Australian Emission Factors Guide
Last updated: April 2026
Summary
- NGA 2025 (National Greenhouse Accounts) is the primary source for Australian emission factors — covers grid electricity by state, transport fuels, stationary energy, and fugitive emissions
- DEFRA 2025 (UK) fills gaps NGA doesn't cover — per-km vehicle factors, international grids, hotel stays, and specific Scope 3 categories
- AASB S2 requires IPCC AR6 GWP values — check that your factors use AR6, not older AR4/AR5 values
- Factors are updated annually — always use the year matching your reporting period
The Three Emission Factor Databases
Australian carbon reporting typically draws from three emission factor databases. Each has a specific role:
NGA 2025
Australian Government
Primary source for Australian domestic operations
Grid electricity, gas, transport fuels, fugitive emissions
DEFRA 2025
UK Government
Supplementary — fills gaps in NGA
Per-km vehicles, hotel stays, international grids, waste by type
EPA GHG Hub 2025
US Government
For US operations or US-based supply chains
US grid factors (eGRID), US transport, US industry-specific
Grid Electricity Factors by State (NGA 2025)
Electricity emission factors vary significantly by state because each state has a different energy mix. Victoria's grid is carbon-intensive due to brown coal, while Tasmania and South Australia are among the cleanest grids in the world.
Scope 2 — Grid Electricity (Location-Based)
| State/Territory | Scope 2 (kg CO2-e/kWh) | Energy mix |
|---|---|---|
| NSW & ACT | 0.64 | Black coal + growing renewables |
| VIC | 0.78 | Brown coal dominant (Latrobe Valley) |
| QLD | 0.67 | Black coal + gas + growing solar |
| SA | 0.22 | Wind + solar majority |
| WA (SWIS) | 0.50 | Gas + coal + growing renewables |
| TAS | 0.20 | Predominantly hydro |
| NT | 0.56 | Gas dominant |
National residual mix factor: NGA 2025 also provides a national residual mix factor (0.81 kg CO2-e/kWh Scope 2, 0.11 Scope 3) for market-based Scope 2 calculations. This is a single national figure, not per-state.
Transport and Stationary Fuel Factors (NGA 2025)
Common Transport Fuels — Scope 1
| Fuel | Unit | Scope 1 (kg CO2-e) | Common use |
|---|---|---|---|
| Petrol (gasoline) | per litre | 2.32 | Cars, light vehicles |
| Diesel | per litre | 2.71 | Trucks, utes, generators |
| LPG (autogas) | per litre | 1.56 | Forklifts, older vehicles |
Stationary Energy — Scope 1
| Fuel | Unit | Scope 1 (kg CO2-e) | Common use |
|---|---|---|---|
| Natural gas | per GJ | 51.53 | Heating, cooking, hot water |
| LPG (stationary) | per GJ | 60.6 | Rural heating where no gas mains |
When to Use DEFRA Instead of NGA
The NGA is comprehensive for Australian domestic operations, but it has gaps. Use DEFRA 2025 for:
- Per-kilometre vehicle factors — NGA provides per-litre factors, but if you only know kilometres driven (e.g., from GPS tracking), DEFRA provides factors by vehicle type and size per km
- Business travel — flights (by cabin class and haul distance), hotel stays, rail travel, taxis
- International electricity grids — if you have operations outside Australia
- Waste by disposal method — landfill, recycling, composting, with factors by material type (paper, plastics, food waste, etc.)
- Water supply and treatment — factors for water consumption and wastewater
- Refrigerants by specific gas — NGA covers some, but DEFRA has a more comprehensive list of HFC/PFC gases with individual GWP values
Worked Examples
Example 1: Office Electricity (Scope 2)
Scenario: Office in Melbourne, VIC — 150,000 kWh consumed over 12 months
Scope 2 = 150,000 kWh × 0.78 kg CO2-e/kWh = 117.0 t CO2-e
Scope 3 = 150,000 kWh × 0.12 kg CO2-e/kWh = 18.0 t CO2-e
Example 2: Vehicle Fleet (Scope 1)
Scenario: 10 diesel utes, total 60,000 litres diesel consumed per year
Scope 1 = 60,000 L × 2.71 kg CO2-e/L = 162.6 t CO2-e
Example 3: Natural Gas Heating (Scope 1)
Scenario: Warehouse in Sydney — 800 GJ natural gas per year
Scope 1 = 800 GJ × 51.53 kg CO2-e/GJ = 41.2 t CO2-e
GWP Values Required by AASB S2
AASB S2 mandates IPCC AR6 (Sixth Assessment Report) global warming potential values with a 100-year time horizon. Key values:
| Gas | Formula | AR6 GWP (100yr) | Common source |
|---|---|---|---|
| Carbon dioxide | CO2 | 1 | Fuel combustion |
| Methane | CH4 | 27.9 | Natural gas leaks, landfill |
| Nitrous oxide | N2O | 273 | Fuel combustion, agriculture |
| HFC-134a | CH2FCF3 | 1,530 | Car air conditioning |
| R-410A | HFC blend | 2,256 | Commercial HVAC systems |
Watch out: NGA 2025 factors use AR5 GWP values (CH4 = 28, N2O = 265), not AR6. AASB S2 requires AR6 values (CH4 = 27.9, N2O = 273). AASB S2 paragraphs AusB22.1–2 allow NGER reporters to use AR5-based NGA factors, but check with your assurance provider whether GWP adjustment is needed for your report.
Common Pitfalls with Emission Factors
- Using last year's factors: Grid factors change annually as the energy mix shifts. Always match the factor year to your reporting period
- Wrong unit conversion: NGA reports natural gas in GJ; your bill may show MJ or cubic metres. Double-check your unit conversions (1 GJ = 1,000 MJ; 1 m³ natural gas ≈ 38.7 MJ)
- Mixing per-litre and per-km factors: Don't apply a per-litre diesel factor to a kilometres figure — you need to know either litres consumed (NGA factor) or km driven (DEFRA factor)
- Forgetting Scope 3 energy factors: When you burn fuel (Scope 1) or use electricity (Scope 2), there are also Scope 3 upstream emissions from extracting, refining, and transporting that fuel. Report these separately
- Using wrong state for electricity: If your company is headquartered in SA but has a warehouse in VIC, each facility uses its own state's grid factor. Don't apply SA's low factor to Victorian electricity
Frequently Asked Questions
What emission factors should I use for carbon reporting in Australia?
What is the grid emission factor for electricity in NSW?
What is the emission factor for diesel in Australia?
When should I use DEFRA instead of NGA emission factors?
Do emission factors change every year?
What GWP values should I use under AASB S2?
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