Band of Equilibrium

Targets for sustainability indicators will typically extend over a range of parameters (a band of equilibrium); these should be set with the involvement of stakeholders. This approach is in contrast to a single reference point, which is sometimes taken as an optimum state for sustainability.

The unit of measure for a sustainability indicator should be clearly stated (for example kg or tonnes of CO2 emissions) and the measurements can then be related to a band of equilibrium on which progress towards, or recession from, sustainability could be judged.

Band of equilibrium values for a range of sustainability indicators might, for example, be standardised into a rating scale of 1 to 10, representing progress towards sustainability, with 10 being the best value in the range. Low values, especially less than 1, would indicate a significant recession away from sustainability, whilst higher values would indicate a strong progress towards sustainability, or even beyond sustainability where the value is greater than 10. An example of how a band of equilibrium can be represented and interpreted (as a slice of pie) is given in the figure below.