How the calculations work

Our calculator is based on research done by the UK Government’s Department for Environment, Food and Rural Affairs (DEFRA). We take the facts you supply about your energy consumption and use conversion factors supplied by DEFRA to convert that into the amount of CO₂ you produce.

Inevitably some of these calculations are approximations: for example, we take the average fuel consumption of cars with a given engine size. The actual fuel consumption of an air passenger depends on a whole range of factors – the weather, the length of journey, the type of aircraft, how heavily loaded it is, and so on. You can find conversion factors for all our calculations on the DEFRA website.

Once we know how much CO₂ you produce, we suggest you give £10 per tonne. The cost per tonne of CO₂ sequestered varies greatly between projects. We invest in biodiverse planting of indigenous trees that bring additional benefits, such as an improved environment for wildlife and/or for people. On average we aim to spend £8 per tonne directly on the projects. The other £2 helps towards the essential running costs of the organization, such as setting up new projects, managing the website and accounting, and making people aware of the services we offer.

We use a scientifically validated model called CO₂Fix to calculate how much CO₂ our projects absorb. This takes account of a wide range of factors such as the species of tree, climatic factors, survival rates and ultimate use of any timber. We calculate the amount of CO₂ absorbed over a period of 50 years but we are actually planting new forestry which we hope will survive for hundreds of years and continue to absorb CO₂ in the long term. When you give to Climate Stewards it is important to realise that the trees we plant are for the long term. Our calculations for the absorption of your and other’s emissions in based on carbon stored over a 50 year period. It is not a quick fix and it is much better if you can avoid the emissions in the first place.

Why should you give to Climate Stewards when some commercial organisations will offsets your emissions more cheaply per tonne of CO₂? Climate Stewards has committed to choose projects that have benefits other than just absorbing your CO₂ emissions. Whenever we plant trees we ensure that we use a wide variety of native species which improve the biodiversity of the eco-system they are grown in. We always involve the local community and by ensuring that they experience some benefits from the planting we gain their long term commitment to the projects and give the trees the best chance of long term survival.

Thank you for giving to Climate Stewards. Every pound helps reduce the impact of climate change on us all.