Green Walls, also referred to as: Living Walls, Vegetated Walls, Vertical Gardens, Green Facades, Biowalls, are comprised of two basic parts; a community of plants trained to grow on a vertical surface, and a substructure that supports the root systems and in some cases waters them as well. This substructure also anchors the plants to the vertical surface, for example a building wall.(source 1) Pre-vegetated or planted on-site panels of plants, growing medium, and support structure, work together in this system.(source 2) Green walls may incorporate hydroponics or a soil/growing material. Hydroponics uses recirculation of water to deliver nutrients directly to the roots of the plant material. In a soil or growing medium-based wall, modules contain the medium and the plants.

Living walls may have human health benefits. They are aesthetically pleasing and help create attractive cities and communities, and may also improve human health through increasing contact with nature. Additionally, living walls that are designed with specific species in mind may create ecological stepping stones and potentially even increase biodiversity. Further, if appropriate plants are used in the creation of the living wall, they could improve air quality (air filtering plants) or water quality (using the root systems to treat water as it trickles down the wall). While performance metrics haven’t been used consistently, social metrics of public opinion, and ecological metrics, such as the size of a target population or number of species present could be used depending on a project's goals.(source 3)


Sources:
1. http://www.greeninfrastructurewiki.com/page/Living+Wall
2. http://www.greenroofs.com/green_walls.htm#March2008
3. http://www.greeninfrastructurewiki.com/page/Living+Wall