Green walls, green facades or vertical gardens can be easily applied to any indoor or outdoor facade or vertical surface that is approved structurally supportive of the installed living systems.  Specific design, installation and maintenance considerations will vary according to the type of system applied and the conditions of both the living and built environment. 
The greatest potential for the application of green walls is in developed urban and suburban areas with  decreased  “natural” areas and higher impervious surface areas.  As a result of this decrease in available urban “green” space, green wall installations have gained greater popularity over the years.   They are amongst the newest trends in “living architecture” that provide environmental, economic and aesthetic benefits on both the private and public realm.  Green Walls are an aesthetic variation amongst an otherwise ordinary urbanscape and therefore provide psychological and therapeutic value for the greater community.  Green walls can range from a simple green wall to a complex artistic composition of varying textures, colors and plant types.  Various research has proven that a sensory experience with plants improves human physical and psychological health, contributing considerably to one's well being. The use of green walls has also become an impacting marketing strategy for small businesses and corporate companies.   As a cosmetic boost to indoor and outdoor business facades, green walls attract the attention of individuals and can therefore increase the levels of retail traffic and create an impacting visual impression in one's mind. (see case study c)

Depending on the type of system used and the plant material environmental benefits can include:

• decreased storm water runoff, capable of retaining 60 to 100% of water during a rain event
• Sustaining Biodiversity: Urban wildlife and insects use and inhabit Green Roofs and Living Walls in the urban landscape; promoting important ecological functions such as pollination, decomposition, and pest control.
• Improving Thermal Performance: Heat flow through the roofing system is reduced by 70-90% in the summer and 10-30% in the winter.
• Increasing Sound Insulation, And Protection of the Roof Membranes: Vegetation, growth medium, and trapped air can increase the effectiveness of building sound insulation by absorbing or reflecting sound frequencies.
•  Reducing the Urban Heat Island Effect (UHI): Vegetation mitigates the UHI but by warming the air less; vegetation reflects solar radiation that would otherwise be absorbed by roof surfaces.  If only 6% of Toronto’s roofs were covered with a green roof would reduce regional energy demand by up to 5-10%, saving more than $1 million in annual energy costs
• Improving Air Quality and Reducing Airborne Particulates: Green plants capture airborne pollution in two ways: absorption or by adhering to the leaf or stem surface. Green roofs and living walls can complement, and in some cases, almost equal the capacity of removing pollutants as existing trees. Increasing soil depth and plant coverage influence the amount of CO2 and other airborne particulates captured; intensive green roofs reduce pollution more than extensive green roofs.  Interior green walls also improve indoor air quality, helping to reverse the affects as what the EPA defines as Sick Building Syndrome (SBS), inadequate ventilation, and chemical and biological contaminants from indoor surfaces.

Source:
http://www.eltlivingwalls.com/general-benefitshttp://www.greenroofs.com/content/green_walls002.htm