Measuring carbon emissions

Some help if you are scratching your head about measuring carbon emissions.

Scope 1

Scope 1 covers direct GHG emissions from operations owned or controlled by your company, e.g. emissions from the combustion of fossil fuels from heating and vehicles.

Scope 2

Scope 2 covers indirect GHG emissions from the generation of purchased electricity, e.g. emissions from the combustion of fossil fuel used to produce electricity.

The ARIES Carbon Reduction Management Plan Template (which you can download from the ARIES website: provides tables to record and data to calculate your emissions. Our original discussion paper has similar useful guidance.

This table has been provided by an ARIES Subject Matter Expert via DEFRA, which you can copy and use as evidence of your annual workings within your plan.

Category	Emission	Units	2024 (kg)	2025 (kg)
Scope 1: Building Energy	Natural Gas	kWh	0.1829	0.1830
Scope 1: Passenger Vehicle	Average Car (Unknown Fuel)	Miles	0.2686	0.2692
Scope 2: Purchased Energy	Purchased Electricity	kWh	0.2070	0.1770

Scope 1 Gas

There are a number of related gases, but if this is your first year, focus on purchased natural gas, total kWh, and conversion into tonnes of CO2 (tCO2e). The current calculation for natural gas is 0.183 kgCO2e per kWh, so from your energy invoicing:

Total kWh X 0.183 = kgCO2e / 1000 = tCO2e

Scope 1 Vehicles

List the vehicles you have control over, the mileage for the year, and the kilogrammes of CO2 per mile for each, then convert tCO2e. The average CO2 per car is 0.269 kg per mile:

Total miles X 0.269 = kgCO2e / 1000 = tCO2e

Scope 2 Electricity

Confirm what you have spent on electricity in the year, calculate kWh by the average pence per kWh. Purchased electricity is 0.207 kgCO2e per kWh, so:

Total kWh X 0.207 = kgCO2e / 1000 = tCO2e

(For those purchasing electricity via the Renewable Energy Guarantees of Origin (REGO) certification scheme under a green tariff, Scope 2 will be zero).