In closing his 2008 Myer Lecture, the scientist and environmentalist Dr Tim Flannery said that this century will be defined by the search for sustainability. How perilous therefore that nowadays there is so much overuse of the word “sustainability” that it has become a cliché. Today's tertiary students studying architecture and energy-related subjects are so exposed to this linguistic devaluation that most of them appear to have accepted the vagueness of the term and are on their way to becoming the next generation of misusers. This paper presents a case study of an attempt to sharpen up the debate with some university students from these particular disciplines. A model of the four principles of sustainable development that has been found to be particularly useful is described. The students in question were challenged to think about the meaning of some of the words ascribed to new buildings and about the implications of the four principles to energy supply systems.