This chapter considers how notions of (in)efficiency and waste have been dominant in the evaluation of energy consumption. It provides a critical understanding of energy consumption and the demand that underpins it, and considers ways in which energy use can be seen as excessive, wasteful and caught up in unsustainable dynamics of accelerating social change, commodification and globalisation. The chapter highlights the considerable complexities involved in: measuring patterns of global energy demand and their variation over space and time, and reducing energy consumption levels in response to the growing pressures of climate change, security concerns and cost. It examines different ways of conceptualising the making of energy demand and how and why it changes. By far the dominant way of approaching energy demand reduction is to focus on improving energy efficiency and reducing waste. The notion of embodied energy highlights that all items that are produced, transported and sold require energy consumption during their production, transportation and selling.