Every unit of grid electricity, green tariff or not, is accounted for at the grid average emission factor, which reflects the mean emissions of power carried over the national grid and takes no account of tariff type or supplier claims. The one exception arises where the supplier can show the tariff's carbon benefit to be genuinely additional. An organisation on a green tariff that satisfies the good quality criteria in Annex G of the Environmental Reporting Guidelines may add a separate, supplementary figure for the emissions reduction the tariff implies; that figure shall stay outside the reported totals, cannot be used to set or track emissions targets, and must rest on the additional carbon saving attributable to the tariff, which the supplier should be able to document.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.