How WLT Calculate Your Emissions
The lifestyle calculator allows individuals to calculate the carbon dioxide emissions associated with their household energy use and travel. These two areas are responsible for the majority of an individual’s carbon footprint. The following information explains how WLT calculates emissions based on the information you supply.
To make sure Carbon Balanced calculations are based on the best available science, WLT uses the most recent Defra (Department for Environment, Food and Rural Affairs) approved conversion factors. These can be found in Guidelines to Defra’s greenhouse gas (GHG) conversion factors for company reporting (PDF) 
. These ‘conversion factors’ are figures that equate specific activities – the burning of one litre of fuel oil, for example – with the precise volume of greenhouse gases produced as a result.
It has been well documented that aviation is responsible for a significant volume of carbon dioxide emissions. The IPCC (Intergovernmental Panel on Climate Change) advises that due to the emissions at high altitude and additional emissions of NOx, water vapour, particles and the formation of contrails and enhanced cirrus cloudiness, aviation has effects on climate far beyond that resulting from CO2 alone. To take this into account scientists have devised a multiplier called the ‘Radiative Forcing Index’ which is applied to CO2 emissions. This is currently an active area of research and at present there is no standard figure. The IPCC estimates that Radiative Forcing can have an affect on the atmosphere between 2-4 times that of CO2, whilst Defra suggests a figure of 1.9. For the time being WLT will use a factor of 1.9, but will continually review the science and advice surrounding this issue.
By applying conversion factors to the information supplied online the Carbon Balanced calculator computes the total emissions offset required, and calculates the cost of taking this action.