An important element to attract partners and secure their commitment is to show the ROI or Return On Investment.

Public players are probably not really used to this way of working. Furthermore, it is not always easy to make exact calculations. Nevertheless, the exercise in itself may clarify a lot of things, as it shows the added value in a very rational manner. Developing knowledge, participation, social impact etc. obviously also add value to the project. However, they are not necessarily the best arguments to step away from short-term thinking and pursue sustainable solutions.

For instance, the purchase of movable, self-sustaining green modules may seem very expensive. However, a useful comparison can only be made if you calculate the cost of labour, materials and equipment (tank truck etc.), water consumption etc. required for the maintenance of “ordinary” green elements.