by Laurent Lefèvre and Jean-Marc Pierson

Introduction to the special theme "Towards Green ICT"

Energy concerns have been developing now for several years, and the ICT domain cannot escape from this trend. As the title of this special issue suggests, we have gathered here articles reflecting two aspects of the links between energy and ICT.

On the one hand, ICT plays a daily part in the production and use of electricity, from the operation of power plants to electricity transport. More interestingly, ICT is used to model, simulate and optimize these processes. The use of ICT to improve energy efficiency and reduce costs is the subject of a number of papers in this special theme.

On the other hand, ICT itself uses a lot of electricity, and work has begun on reducing the consequent economic and ecological costs. It is estimated that the 1.5 billion computers in the world consume about 90 000 MW of electric power, which is about 10% of global consumption. Some surveys commissioned by the European Union in 2006 on energy use and the efficiency of equipment in buildings tell of a continuous growth in recent years in energy consumption of computer end-use equipment (amongst others). Additionally, energy consumption for servers worldwide has doubled over the period from 2000 to 2005. Recent estimates at the CeBit forum 2008 in Hanover, the world’s largest technology fair, proclaimed that worldwide Internet usage, via the necessary computers and servers, needs the equivalent of fourteen power stations and produces the same amount of carbon dioxide as the entire airline industry.

As an example, an operational Grid such as EGEE (Enabling Grid for E-sciEnce) consists of around 150 000 cores distributed over 54 countries and 267 sites (, October 2009). The world’s 500 most powerful machines (, June 2009) have more than 3.1 million processors. Number one on the list (RoadRunner from the United States Department of Energy) consumes 2483 KW of electricity while number two (Jaguar from Oak Ridge National Laboratory) consumes 6950 KW! With new Petaflop data centres in the offing, these energy costs are expected to increase significantly.

As large-scale distributed systems reach enormous sizes, the issue of energy consumption is becoming one of the primary challenges for large-scale integration.

There has traditionally been a dearth of eco-awareness in the computing industry. Moore’s Law has not led to the overall power savings that miniaturization should allow. Instead, greater capacity and capability have invariably taken precedence over eco-concerns. Despite the fact that it has now been several years since makers of mobile and embedded systems began to take energy use into account, ecological concerns have not been prioritized in assessing the total collective costs of large-scale distributed technology. Constructors have worked on addressing individually the numerous components of computer architecture, but usage (in networking, storage and computing) has long been ignored.

Ecological impacts constitute a silent cost which until recently received little attention. However, new studies commissioned by government institutions will consider energy efficiency procedures for servers and data centres. White papers exist to establish better use of ICT infrastructure. Strategic issues in the management of such infrastructure and the benefits to economy and enterprise image are being investigated. Another aspect is the continuous raising of public consciousness of the need to save energy and reduce global consumption. Exposing electricity consumption visually to consumers (including by marketing) is an objective targeted by several projects.

Interest in the energy-saving theme from both governments and researchers has increased exponentially in recent years. In early 2000, work done in the USA (Green Destiny) and Japan launched sparked initial interest in energy-aware computing. Recent initiatives such as Green Internet and Green500 have addressed this problem. The Green Grid, a non-profit trade organization involving over fifty major companies (including Intel, AMD, Dell, IBM and VMWare) is dedicated to advancing energy efficiency in data centres and business computing ecosystems. It develops standards, metrics, processes and technology to improve performance, and promotes their widespread adoption. Additionally it investigates approaches that rely most of the time on more energy-efficient hardware and electronics (in particular power supplies).

Surprisingly, European environmental research themes are not yet investigating the issues related to electricity consumption in IT. The environment theme of the FP7 (Framework Programme 7) focuses its actions on environmental issues and climate change, but ignores ICT. However, the energy theme is concerned with energy consumption and production, and has several projects that use ICT. In the ICT theme, Challenge 1 on pervasive and trusted network and service infrastructure and Challenge 6 on mobility, environmental sustainability and energy efficiency address this question. These programmes have at least raised a number of projects with some eco-awareness. For example, the Virtual Home Environment (VHE) project, a specific subproject of the European Network of Excellence Euro-FGI is looking at energy-efficient home networking, and the AIM and BE-AWARE projects (answers to the ICT-2007.6.3 ICT call for environmental management and energy efficiency) are investigating complementary approaches with different perspectives for eco-awareness. National research initiatives (like EcoGrappe or GreenNet projects in France) also address the issue of energy savings in ICT.

Recently, the European COST Action IC0804 (Energy efficiency in large-scale distributed systems) is giving a voice to this theme ( The aim of this action is to encourage researchers in this field to cooperate and build on common research topics.

The papers presented in this special issue are divided into five groups. The issue begins with (1) some general considerations, strategic issues and the rise of eco-awareness (six papers), followed by a (2) couple of papers on efforts in electronics, and on (3) data centres and clusters (two papers). A significant number of contributions represent (4) advances in IT methodologies and developments towards eco-friendliness (eight papers), especially in large-scale distributed systems. Finally, the issue closes with four papers dealing with (5) the usage of ICT as a means of saving energy.

Please contact:
Laurent Lefèvre
INRIA, University of Lyon, France
E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Jean-Marc Pierson
IRIT, Université Paul Sabatier, Toulouse 3, France
E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.


“Green ICT” Conferences

A list of relevant conferences focused on green computing and energy-aware computer and network architectures and technologies, or containing tracks on these topics is maintained by Jordi Torres and Josep Lluís Berral García, Technical University of Catalonia (UPC) at

Next issue: April 2019
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