The two main types of living walls are:
- extensive: this is the traditional method. Climbers are planted at the foot of the wall and spread, extensively, over the surface of the wall
- intensive: this is a new method, particularly associated with Patrick Blanc (who describes the results as ‘Vertical Gardens’). It is intensive and makes use of irrigation, electricity, fertilisers etc
The distinction between intensive and extensive comes from the classification of green roofs as ‘extensive’ if they are low-maintenance (sedum roofs, native plants etc) and ‘intensive’ if they are managed as gardens with high-maintenance (exotic plants, irrigation etc).
Both types of green living wall can contribute to sustainability objectives. Extensive green walls can: insulate walls, provide wildlife habitats, lessen sound reflection, assist evapo-transpiration, produce urban food, attract and remove dust and other particulates. Intensive green walls can also have these roles but their sustainability credentials are diminished by their use of energy and materials.