The World is facing major challenges regarding environmental threats, resource constraints and the large unbalance of wealth among developing and developed countries. Energy engineering is at the core of the actions to be undertaken to meet these challenges in a harmonious way within the framework of strong economic constraints. The rational use of energy, materials and capital, as well as an increased use of renewable energy constitute some of the essential ingredients of more sustainable policies. Energy eco-efficiency can be improved in particular by developing more holistic design and planning methodologies, by defining more appropriate indicators and by developing more advanced conversion technologies. An adequate presentation of the engineering results, capitalizing on information technology approaches, is also seen as a path to promote a more constructive dialog with policy makers.