Global energy use, fossil fuel carbon dioxide (CO2) emissions, and atmospheric CO2 levels continue to rise, despite some progress in mitigation efforts. Improving energy efficiency is seen as an important means of reducing emissions, but absolute reductions in global energy use remain elusive because of energy rebound and continued growth in the numbers of important energy-using devices such as transport vehicles. Limiting the rise in average surface temperature above pre-industrial to 2 °C or even 1.5 °C is widely regarded as necessary for avoiding dangerous anthropogenic climate change. Given the magnitude of CO2 emission reductions necessary for this limit to be met, other approaches are needed for reducing energy use and its resultant emissions. This chapter discusses social efficiency (non-technical means for reducing energy use that stresses the social and environmental context in which energy consumption occurs in various sectors.) Three important sectors for energy use, transport, buildings, and agriculture, are used to illustrate the potential for social efficiency in energy reductions. We argue that by focusing more clearly on the human needs energy use is meant to satisfy, it is possible to find new, less energy-intensive ways of meeting these needs.