How Our Carbon Calculator Works

From what we’ve seen, other carbon offsetting sites produce carbon emissions figures that are vastly over-estimated. We use the following information to base our calculations on, and constantly check the latest emissions reports for all energy providers.


Carbon Emissions Generated By Energy Consumption

We use the following costs to calculate your energy consumption if you only specify cost: 10p/kWh electricy, 6p/kWh gas. Figures were obtained from here.

Average Household Energy Consumption Per Bedroom (more details)

Number of Bedrooms Average kWh Consumption Per Year (Gas) Average kWh Consumption Per Year (Electricity)
1 10,000 2,500
2 15,000 4,000
3 25,000 5,500
4 29,000 6,000
Consumption per additional bedroom 2,500 250

Carbon Emissions per kWh per Energy Supplier (more details)

Supplier Carbon Emissions (kg)
Average (electricity) 0.461
Brittish Gas (electricity) 0.354
EDF Energy (electricity) 0.527
Good Energy (electricity) 0
npower/RWE (electricity) 0.507
Powergen (electricity) 0.619
Scottish & Southern Energy (electricity) 0.520
Scottish Power (electricity) 0.580
Average (gas) 0.19

Carbon Emissions Generated By Consumer Goods

We worked out a rough figure for consumer wast/emissions from these sources: here or here.

A green consumer will produce around 1 tonne, and an average consumer around 2 tonnes per year. You can calculate a more accurate figure using the resources on those sites, but these figures are accurate enough for most uses.


Carbon Emissions Generated By Transport

DEFRA produced a list of emissions figures which provides information on rail transport here. From that we have an average figure of 0.064374 tonnes of carbon dioxide emissions per mile for electric trains based on average National Grid prices.

For flight distances, we work out longest distances for three flight types from here.

Flight Type Max Distance (miles) Carbon Emissions (kg max) Carbon Emissions (kg/mile)
Short 500 120 0.241402
Medium 3,000 750 0.225709
Long 13,000 2,300 0.177028

For emissions from automotive transport we use carbon emissions data in terms of g/km from here. To enter more accurate information into our carbon calculator, look up your car information there.