Walls have become the metaphor of choice for isolation in an increasingly material and bureaucratic world. The green wall is the innovation supplanting this tired metaphor, with a literal wall made up of refreshing array of plants that can purify our air supply, give our eyes a much needed break from all that grey concrete and breathe new life into our sense of style.
Originally patented as Vegetal-walls, the green wall has been making a resurgence in many countries such as Australia and city states like Singapore. It is even being hailed as one of the solutions to the highly polluted environment of heavily industrialized China.
There are two main groups of green walls: walls where the root system is divided through the wall are called living walls, whereas walls utilizing a separation construction are called green facades. They can be used indoors or outdoors.
Soil-less vertical green wall at Hougang Primary School. Photo: Hougang Primary School. Source: Today Online http://www.todayonline.com/singapore/vertical-green-wall-school-helps-fight-global-warming
Growing the Vertical Garden
There are 3 widely agreed upon methods of growing green facades. The first and most common approach is to grow the plants vertically along a wire along the building. While relatively cheap, it does require significant waiting time for the plants to grow to the desired consistency. The second method involves constructing a separate frame with an air gap in between the building and frame. The frame has numerous flowerpots inserted with growth mediums. The third method uses the same frame with the exception of cages with crushed bricks full of seeds as opposed to flowerpots.
The plants are watered in mainly two ways, recirculating and direct irrigation.In recirculation, a water tank is placed directly below a tank. Excess water returns to the tank via gravity and is recirculated to the plant. The water tank must be refilled manually. Direct irrigation on the hand does not use a water tank; the water is pumped directly from a source e.g rainwater or city water, and the excess water leaves via drainage without being recirculated.
Living walls occur naturally and are a great example naturally occurring hydroponics. The reception Living Walls as a decorative function on buildings has been mixed as the plant growth causes cracks. Besides naturally occurring Living Walls, hydroponic living walls can be grown as DIY project with the right tools.
Benefits of the Green Wall
The green wall has a wide array of benefits besides exchanging the carbon dioxide we generate into oxygen. The sheer number of plants amplifies an air purification effect, drastically reducing levels of harmful pollutants like nitrogen dioxide. There is also the phenomenon of “sick building syndrome”, where we are exposed to gases such as formaldehyde, used in the construction of many commercial buildings. The green walls have been proven to remove these harmful particles.
Besides being a natural air purifier, green walls naturally divert rainwater from buildings, countering the urban building heat effect by significantly reducing the overall temperature and providing shade. The green walls have a surprising dual function of cooling the air temperature through a process known as evapotranspiration, and providing heat insulation through the growth mediums. The green wall is a multifaceted technological and natural miracle, saving us from building costs, environmental pollution and the concrete grey isolation of modern architecture.
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- Ariz Ansari, ADI Intern