Some active walls are kept behind glass to ensure more predictable airflow than can be achieved with inactive walls, which have no mechanized air circulation. Instead, they are kept open to promote as much free air circulation as possible.
Green walls are mostly used in urban environments where the plants can reduce overall temperatures of the building which in turn reduces energy consumption.
They may also be a means for water reuse.
The plants may purify slightly polluted water (such as greywater) by absorbing the dissolved nutrients.
Bacteria mineralize the organic components to make them available to the plants.
It may be built for aesthetic reasons to give a beautiful look to the building.
The supply of moisture to the soil is critical to the survival of a green wall. Although it may sound like an elementary process, it could be a complex operation.
The supply of water, how it will be supplied, and some inherent problems with water types are all factors that need to be considered in the design process so that plantings can be successful and economical.
In a country like Qatar where rain water is scarce, effort should be made to look for environment-friendly irrigations systems. A sensor-controlled drip irrigation system uses a minimum amount of water. Nevertheless, the ecological benefits of green walls surpass their irrigation challenges.
The choice of the right plants is another challenge of building green walls in Qatar. Your best bet is to choose local plants. This way you will know that they could withstand the hot and humid weather that we experience most of the year in Qatar.
Climbers can dramatically reduce the maximum temperatures of a building by shading walls from the sun, the daily temperature fluctuation being reduced by as much as 50%. The Weather Channel Interactive points out that the effectiveness of this cooling effect is related primarily to the total area shaded rather than the thickness of the climber.
Together with the insulation effect, temperature fluctuations at the wall surface can be reduced from between –10º/14ºF to 60ºC/140ºF to between 5ºC/41ºF and 30º/86ºF. The use of climbers to reduce solar heating is most effective if they are used on the wall that faces the sun, together with the west wall, which experiences afternoon heating.
Climbers on buildings can help protect the surface of the building from damage from very heavy rainfall and hail, and possibly can play some role in intercepting and temporarily holding water during rainstorms, in the way that green roofs do.
They also help to shield the surface from ultra-violet light, which might be an important consideration for certain modern cladding materials.
Climbers have been shown to be highly effective at trapping dust and at concentrating certain dust-derived pollutants in their tissues, particularly in those tissues that are then discarded. This feature could be very beneficial in Qatar as we witness frequent dust storms that pose a challenge for tower maintainers and cleaners.
There is also strong anecdotal evidence that climbers on buildings help to reduce noise levels.
All green plants absorb CO2 emissions, thus climbers in urban areas help to reduce the contribution made to human-induced global warming.
All plants also absorb and breakdown a variety of pollutants, notably volatile organic compounds, and unburnt hydrocarbons from vehicle exhaust. It is a reasonable assumption that urban climbers could play a role in reducing these in city areas.
Internationally, green walls are becoming a growing trend, like their counterparts, the green roofs. PNC Financial Services Group recently installed a green wall the size of two tennis courts on one side of its headquarters.
PNC, which provides banking and wealth management services, estimates it will be 25% cooler behind the wall than the ambient summer temperatures.