Figure 2. An energy sufficiency-efficiency cost curve.

A schematic comparison of costs of energy poverty and excess energy consumption. The rough U-shape is characteristic of systems with excess impacts related to extremes of resource access and use. An associated aspect of the process of defining a regime of ‘wise use’ of resources is the role of efficiency relative to robustness of the system. A useful alternate representation is to place efficiency (“streamlining”) and diversity (“robustness”) as extremes on a single axis ³⁸.