The ENERGY STAR program no longer has a separate specification or designation for external power supplies (EPS). This is explained and clarified at the ENERGY STAR program website, see:
Since the ENERGY STAR PC standard specifications ver. 6.1, however, EPS are required to meet the international level V requirements, in order for the notebook to be qualified to ENERGY STAR and all adapters used on our ENERGY STAR products meet this requirement.
For a confirmation, please see EnergyStar Product Specifications.
If asked for a certification on EPS (80 PLUS certification is for internal power supplies only, not external), kindly refer to the above and explain there is no separate certificate, however the requirements are met.