Sustainability can be defined as the ability to maintain healthy environmental, social and economic systems in balance, indefinitely, on a global and local scale.
The spheres of sustainability can be conceptualised as having a nested relationship (Figure 1), with the economy and society a subset of the environment.
Culture is often included as a fourth circle or a subset of society.
The economy is much broader than the regular monetary economy, and includes:
an exchange of goods and services within and between communities, with
a focus on the equitable distribution of scarce resources
at a sustainable scale.
Figure 1: A nested view of sustainability