The Whichgreen Method
How We Calculate The Figures
We’ve been compiling the Whichgreen Tables for six years now. Here’s a quick guide to how we go about things and the measures that we put in place to ensure that our figures are as accurate as possible.
1. New sources of Renewable Electricity (Wind, Hydro & Biomass) over 50kW in capacity and commissioned during the year are identified using Ofgem & BWEA data.
2. Only new sources of renewable electricity are included. Where sites are repowered only the increase in net capacity (the new capacity) is considered and any investment is proportionally attributed. Sites that are refurbished, but with no increase in net capacity, are not included in the Whichgreen figures.
3. Where investment figures are available within the public domain (e.g. via press releases) these are included in the calculation.
4. For all other generators a figure is calculated based upon the installed capacity and costings published in the Enviros Consulting report “The Costs of Supplying Renewable Energy” – available on the BERR website .
5. Domestic electricity customer numbers for each supplier are obtained from Ofgem or from material released by the suppliers themselves.
6. The £ spent per customer figure is calculated by taking the sum total of investments made during the year for new generation capacity and dividing by the total number of customers. It’s as simple as that.
7. Once compiled, the relevant information is then sent to each individual supplier to allow them to check its authenticity and to correct any inaccuracies regarding the generating stations included, the amounts invested and customer numbers.
8. Only when we are happy that any outstanding matters with suppliers regarding these figures are resolved, are the Whichgreen Tables published.