science principle 2   open to throughflow of energy

The Natural Step™ (TNS) is a practical communication and planning model for sustainability. "TNS offers a framework that is based on science and serves as a compass for businesses, communities, academia, government entities and individuals working to redesign their activities to become more sustainable.

system condition 3   meeting system condition 3

The Natural Step encourages dialogue and consensus building, a key process of learning organizations. It is based on systems thinking, focusing on first-order principles at the beginning of cause and effect relationships. It recognizes that what happens in one part of a system affects every other part, often in unexpected ways." (

Explanatory article.
Information on a process for applying The Natural Step.
Click here for an animation of the ecocycle.