Unsustainable consumption mostly refers to energy resources and materials' utilization, fostered by human activity. Therefore, energy consumption represents a major challenge when approaching sustainable development issues. Despite many environmental strategies relying on improvements in energy and material efficiency, the World's energy demand is likely to increase in line with its population. In addition, cultural patterns of human activities are closely related to energy consumption patterns. This paper discusses the relationship between energy consumption and human overpopulation, which is one of the critical issues when approaching sustainability. Furthermore, this paper argues about cultural influences and barriers for the rational use of energy. The paper juxtaposes shallow to deep ecology and stresses the importance of transition to deep ecology, which draws on a wide diversity of ultimate philosophical or religious premises, by seeing Nature and culture as fundamentally intertwined. Education has a crucial role in revising energy consumption patterns. This paper also stresses the importance of education for sustainable development as a required approach to a sustainable society. It argues about those conflicts between different human goals that should be taken into account in educational systems. Universities should act as agents in promoting transformative change towards sustainability. Thus, the importance of incorporating sustainability principles into universities' activities is discussed in the paper. Several activities and projects at the University of Maribor, embracing all departments and their everyday activities, are presented as an example.