Towards a metric for the energy efficiency of computer servers

A globally accepted metric on the energy efficiency of computer servers in business applications is still missing, despite a great interest from stakeholders. In the context of the implementation of the European Ecodesign Directive, a detailed analysis has been carried out on the feasibility of policy requirements for computer servers addressing, among others, the relation between energy use and performance. The lack of such a metric weakens the effectiveness of a regulation on the server energy efficiency in “on-mode”. "Capping" energy use would be the alternative, although complex and disputable because of virtually unlimited internal configuration options of the products placed in the market. In this framework, a dedicated research stream has been devoted to the development a draft proposal for a metric. The paper describes in detail the procedural as well as the theoretical steps to date. The preliminary results show how the draft proposed metric is representative of the user pattern of servers, scalable, technology neutral and does not entail excessive costs. This work could well represent the basis for an international standard, in particular in the framework of a standardisation mandate from the European Commission on the energy efficiency of information and communication technology products.