How Green Walls Can Help Environmental Management?
The relationship between our environment and health can sometimes be difficult to determine for as number of reasons. For example, effects of the environment may only show up in the longer term rather than have an immediate impact. Some environmental effects may be localised e.g. due to faulty air conditioning whereas others may affect the broader community e.g. pollution from car fumes. Also, different factors can be more prevalent during different seasons e.g. pollen release, or at different times of the day. Furthermore some people are more vulnerable to environmental factors e.g. the frail and elderly, and people can also influence the environment as well as be affected by it. What we can say is that people are able to play a role in influencing risks to health by altering the environment. Green walls are a means of influencing our urban environments for the benefit of people.
Besides their links to health benefits and the obvious aesthetic value, green walls, along with green roofs, have the added benefit of insulating buildings. This effect is most notable in warm and tropical climates where they insulate against excessive summer heat and reduce reliance upon air conditioning units. The shade from trees and shrubs along with water released into the atmosphere when plants transpire helps with the cooling effect in summer heat.
In cold climates plants trap heat and thereby reduce reliance upon interior heating. Thus insulation against temperature extremes helps to reduce energy consumption, and where that energy is derived from fossil fuels it helps to lower greenhouse gas emissions and their contribution to climate change. At a local level, this means less pollution and cleaner air.
Green walls not only provide temperature insulation but sound insulation too. Plants on walls absorb the sounds of city traffic and industry contributing to making urban environments quieter.
Reduced Heat Island Effect
As well as the gains for those inhabiting buildings with green walls, the plants and foliage on the walls soak up heat and have an overall lowering effect on temperatures compared to exposed walls. Urban areas are notably warmer than surrounding areas. In particular, built surfaces like roads, pavements and the roofs and walls of buildings made of concrete, brick and stone are considerably warmer than the air temperature. The elevated temperatures in urban areas in relation to nearby rural locations has long been recognised and referred to as the 'heat island effect'. Green walls have been found to reduce the heat island effect.
The temperature differences in areas with bare walls are exacerbated in the summer and during heat waves. Plants on walls and roofs absorb heat and reduce these temperature fluctuations. So, not only do they enhance insulation keeping occupants cooler in summer and warmer in winter with less reliance on heating and cooling, but they also reduces heat-related health problems like exhaustion and heat stroke. As such, green walls can help protect the most vulnerable in our populations since heat-related problems have the greatest impact upon children and the elderly, as well as those with pre-existing health complications.
Carbon Sinks and Use of Limited Space
Vertical is also advantageous to the environment in the sense that it provides an opportunity to do more gardening in a smaller space. This means that in urban areas there is less need to use prime land for growing so with careful planning you can have a larger green footprint per cubic metre.
On a broader scale plants act as carbon sinks by taking carbon from the atmosphere in the form of carbon dioxide and storing it. With less carbon dioxide floating around this should help to slow climate change. Of course, in order to be carbon sinks there has to be less use of carbon in installing and maintaining plants. If the plants have to be transported great distances to arrive at their destination this uses fuel and vehicles. If the plants are heavy feeders, this uses fertiliser. All these things use up carbon in manufacturing, burning fuels, manufacturing fertilisers, and so forth. If the carbon used exceeds that which is stored, then the plants can no longer be considered carbon sinks even though they do trap and store carbon.
Another considerable environmental benefit of green walls and vertical growing in and around buildings is their effect on the biodiversity of urban areas. All too often when a town or city is built the natural environment is scaled back and habitats are lost. Green walls and façades re-introduce plants to urban areas which in turn attract pollinating insects, wildlife and birds. If used in urban planning, green walls can provide links between wildlife corridors.
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