Internationally standardised certificates offer a more reliable form of evidence of the environmental impact of production than contracts and statistics: statistics are by their nature not accurate, and so they will always misrepresent the energy blend to the consumer; and it is extremely difficult to follow the contractual path from generator to consumer: this can involve many contracts, some of which will not distinguish between energy sources. For this reason, analysing contracts is expensive and prone to error.

The reliability of certificates depends on the presence of a standardised and reliable framework for certificate administration. This is provided by EECS, which addresses all of the administrative aspects and has been developed by an international group of practitioners over several years of practical experience, and is guaranteed by an organisation independent of the market and of any particular certificate system administrator.