Article 3(6) of the Second Electricity Directive provides that Member States must ensure that electricity suppliers specify in, or with, the bills and promotional materials made available to final customers: • the contribution of each energy source to the overall fuel mix of the supplier over the preceding year 

at least a reference to existing reference sources, such as web-pages, where information on the environmental impact, in terms of at least emissions of CO2 and any radioactive waste resulting from the electricity produced by the overall fuel mix of the supplier over the preceding year is publicly available

The aim of these provisions is, amongst others, to increase market transparency by providing open and easy access to relevant information. The Notes provide that the implementation of this labelling provision will be regularly evaluated by the Commission10. One of the key elements of the assessment will be the reliability of the information that is provided to consumers. As more experience is gathered and benchmarking of the different approaches has taken place, the Commission will issue recommendations taking account of any new developments and best practice, especially on the tracking of generation attributes.