By Nicole Stern
Ecological Designer, Biohabitats, Inc.
“Living Walls,” “Green Walls,” “Vine Walls,” and “Vertical Gardens” are all terms used to describe growing plants on a vertical structure. In nature, many plant species grow on tree trunks or on steep, rocky slopes without much soil. Through using adaptations of these and other plant species tolerant of vertical conditions, designing living walls in a variety of settings is all the rage – but hardly a new idea. Examples range from the Hanging Gardens of Babylon to the “ivy” in Ivy League Universities. Recent innovations in the structure of living walls allow much more control and variety of plant palette. Wire trellis encouraging vines up walls are one of the more simple structures, while artists such as Patrick Blanc in France use a thin structure of plastic lining, metal, and thin textiles to support dense swaths of colorful plant species, creating botanical paintings. Other companies offer plastic and metal trays which hold pockets of soil at an angle in a modular wall system. Whether indoor, outdoor, vine, textile/hydroponic, or soil based, living walls offer many benefits including air filtration, cooling, improved aesthetics, water filtration, food growing, and more. The indoor living wall at Biohabitats, for example, pulls air through the structural fabric and rootzone of the plants into the air circulation system for the office to filter office air.
Touted as a “green” technology, these vegetated walls have great potential. They have already been shown to improve indoor air quality. Vertical gardening in dense, urban landscapes offers a potential solution for food production. However, some living walls may be taking more than they give. While visiting a recently installed “green wall” in a store within a shopping mall, I wondered how sustainable some of these walls are if they require artificial lighting, a supply of potable water, constantly circulated by an electric pump through their rootzone, and are separated from any food chains or natural cycles. Does the air purification service and ornament of a living wall balance out energy and water resource demand? Should living walls only be considered a “sustainable” feature if they provide more service than they demand?
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