How does a living wall work?

In this video Gary Grant, an independent ecologist give an introduction to the living wall systems that are available.  He discusses how climbing plants can be used to make a green façade and how modern modular or ‘intensive’ living wall systems can be used make an instant and more diverse impact.  He goes into more detail on the difference between hydroponic living walls (which use Rockwool insulation instead of soil) and natural soil living walls and why if you want more than just a system that keeps plants alive you really must consider soil.  Soil is an ecosystem in itself, it brings biodiversity and gives a cooling buffer by storing water.