Methodology Overview

What is NGER?

The National Greenhouse and Energy Reporting Act 2007 (NGER) requires large Australian corporations to measure and report their greenhouse gas emissions and energy consumption to the Clean Energy Regulator (CER). The NGER (Measurement) Determination specifies exactly how those measurements must be calculated.

For transport, the Determination provides three methods of increasing granularity and accuracy. EmWise implements Method 1 — the fuel-based approach — which is the most accurate method available to operators who track actual fuel consumption by vehicle.

Method 1 explained

Method 1 calculates emissions from the quantity of fuel consumed, the energy content of that fuel, and emission factors that represent how many kilograms of CO₂-equivalent are produced per gigajoule of energy.

It is called "Method 1" because it is the first-preference method under the NGER Determination — reporters should use the most accurate method they can substantiate. For organisations with fuel records (fleet cards, supplier invoices, or telematics), Method 1 is always achievable.

The core formula

energy consumed (GJ) = fuel quantity (kL) × energy content (GJ/kL)

CO₂ (t CO₂-e) = (energy consumed × CO₂ factor) / 1000
CH₄ (t CO₂-e) = (energy consumed × CH₄ factor) / 1000
N₂O (t CO₂-e) = (energy consumed × N₂O factor) / 1000

Scope 1 (t CO₂-e) = CO₂ + CH₄ + N₂O

Scope 3 (t CO₂-e) = (energy consumed × Scope 3 factor) / 1000

Total (t CO₂-e) = Scope 1 + Scope 3

Emission factors are in kg CO₂-e per GJ. Dividing by 1,000 converts to tonnes.

Example calculation

A Sydney–Melbourne B-double (Euro IV diesel) burns 85.4 kL.

Energy = 85.4 kL × 38.6 GJ/kL = 3,296.44 GJ

CO₂  = (3,296.44 × 69.9)  / 1,000 = 230.43 t CO₂-e
CH₄  = (3,296.44 × 0.07)  / 1,000 =   0.23 t CO₂-e
N₂O  = (3,296.44 × 0.4)   / 1,000 =   1.32 t CO₂-e
Scope 1 = 231.98 t CO₂-e

Scope 3 = (3,296.44 × 2.1) / 1,000 = 6.92 t CO₂-e

Total = 238.90 t CO₂-e

Scope 1 vs Scope 3

Scope 1 covers direct combustion emissions — CO₂, CH₄, and N₂O produced when fuel burns in the vehicle's engine. These are the primary emissions reported under NGER.

Scope 3 covers upstream (well-to-gate) emissions from producing and transporting the fuel before it reaches the vehicle. These are sometimes called "fugitive" or "embodied" emissions. EmWise uses the National Greenhouse Accounts (NGA) upstream factors for Scope 3.

NGER reporting focuses on Scope 1. Scope 3 is provided by EmWise for voluntary disclosure purposes (e.g. the Australian Carbon Credit scheme or CDP reporting).

Reporting year attribution

The NGER reporting year runs 1 July to 30 June. Reporting year attribution in EmWise works as follows:

• If departure_date is provided, it is used.
• If only arrival_date is provided, it is used.
• If neither is provided, the submission date is used.

A job dated before 1 July is attributed to the reporting year ending that 30 June. A job dated on or after 1 July is attributed to the reporting year ending the following 30 June.

Job date	Reporting year
30 June 2024	2024 (1 Jul 2023 – 30 Jun 2024)
1 July 2024	2025 (1 Jul 2024 – 30 Jun 2025)
1 January 2025	2025 (1 Jul 2024 – 30 Jun 2025)
30 June 2025	2025 (1 Jul 2024 – 30 Jun 2025)
1 July 2025	2026 (1 Jul 2025 – 30 Jun 2026)

Emission factor versioning

Emission factors are stored per reporting year. The factors for a given year are fixed at the start of that year's reporting period and do not change. If the NGER Determination is updated — which typically occurs annually — EmWise will add new factor rows for the new reporting year without modifying existing rows.

This means a calculation submitted in 2025 for a 2024 job will always use 2024 factors, even if you re-run the report years later.