Green wall definition
A green wall is comprised of plants grown in supported vertical systems that are generally attached to an internal or external wall, although in some cases can be freestanding. Like many green roofs, green walls incorporate vegetation, growing medium, irrigation and drainage into a single system. Green walls differ from green facades in that they incorporate multiple ‘containerised’ plantings to create the vegetation cover rather than being reliant on fewer numbers of plants that climb and spread to provide cover. They are also known as ‘living walls’, ‘bio-walls’ or ‘vertical gardens’.
Green walls provide an attractive design feature, but also add to building insulation by direct shading of the wall surface. They create cooler microclimates and improve local air quality, and provide the possibility of growing plants in locations that would not normally support vegetation. A wide range of plants is used on green walls, usually herbaceous, though some small shrubs can also be suitable. The provision of adequate light is an important consideration, particularly when planning an interior green wall, where artificial lighting may be necessary.
Many different proprietary green wall systems are available. Some are hydroponic and others use a growing substrate. Green wall structures vary from modular systems to sheet or board-based structures with felt pockets to contain and support plant life. All green walls require irrigation, often inclusive of fertiliser (fertigation). Fertigation solution can be re-used, but requires careful monitoring and management to ensure nutrients do not build up over multiple recirculation to damaging levels.
A well-designed green wall system will fulfil both design and functional aims by providing growing conditions suitable for the selected species, have a long lifespan, require minimal component replacement and have achievable demands for maintenance.