‘Keeping the lights on’ is examined and critiqued as a commonplace phrase used in public discussion of energy issues to convey the idea that keeping energy systems working is an essential goal of good energy governance. However, its use is grounded in a set of assumptions about how keeping the lights on is to be ensured and how the relationship between supply and demand is to be managed. Supply-side solutions dominate, being aligned with particular interpretations of the causes of energy crises, and ideas about how these should be handled. This chapter challenges classic ‘keeping the lights on’ thinking that sees energy demand as non-negotiable, lying outside the frame of legitimate policy debate. It calls for a far more fundamental discussion about how much energy is enough; or exactly how many lights (and other energy uses) need to be kept on, now and in a necessarily low carbon future.