I. Introduction
In the quest for enabling a low-carbon and sustainable economy and society, information and communication technologies (ICT) is playing a twofold role. On the one hand, advanced ICT enables to increase the efficiency in a number of industrial sectors (e.g., smart grids), thereby achieving significant reduction in the associated power consumption. At the same time, ICT itself is a major source of CO2emissions. Several studies have shown that the ICT sector is responsible for an estimated 2% - 10% of the global energy consumption [1], [2], [3]. Additionally, ICT sector also produces from 2% to 3% of total emissions of greenhouse gases [4], [5], [6].