September 29, 2022

The benefits of living green walls


Landscaper and arborist Mark Laurence discusses some of the problems faced by the industry in Middle Eastern cities.

With a rise in urbanisation, green infrastructure has become essential to counter our ever-increasing disconnect to nature. Living walls are an important part of this as they deliver huge volumes of green using a very small footprint. But what are the benefits?

On a human level, research shows that close proximity to plants brings many benefits – emotional, physical and spiritual – fulfilling our innate need for nature. This is known as the biophilia hypothesis. We are less stressed and more relaxed when around plants, with higher productivity and less absenteeism at work. Plants are known to cleanse the air of dust particulates and gaseous toxins and add essential moisture back into the air, leading to fewer dry eyes and coughs.

Physical health benefits don’t stop there; studies show that people in hospitals heal faster when they have a direct connection to nature. And, of course, the artistic element of designing with plants is fantastic, giving a huge psychological uplift to those who encounter living walls.

Seeing nature tower above you where once was concrete or steel is an amazing experience. In building design, living walls can contribute to sustainability by reducing heating and cooling costs. They act as an insulating layer, lessening thermal absorption or loss through the building’s skin – regulating the internal conditions and reducing energy use.

They also dissipate sound effectively when used both internally and externally, thus making the home or workplace a more pleasant space to be in. There is also great potential to use green walls as biological water filters, where grey water (from taps within the building) irrigates the walls which cleans the water and returns it to the building to be reused – an example of cyclical design where the building deals with the waste it generates.

Benefits are also apparent in the wider environment. Living walls in a street canyon are known to be efficient filters of airborne particulates (pm10) and gaseous toxins such as NOx, which derive largely from diesel engines.

Air in the street canyon swirls through the foliage, which deposits the particulate and encourages gaseous exchange. Living walls are more effective than trees in this respect – trees can trap pollutants at street level and often lose their leaves for a part of the year. Living walls can also contribute to the reduction of urban heat island effect, which is where the urban fabric absorbs heat, re-radiating it at night. If the building is clothed in green, which gives off moisture through evapotranspiration, then the surroundings stay that bit cooler. Finally, living walls are essential for urban biodiversity, providing shelter and food sources for insects, which are the basis of all ecology.

Creating extensive living walls in arid climates is not without challenges and, in the case of external walls, comes down to the right system and plant selection. Both need extensive testing to prove suitability (something this author has been doing), but the benefits are heightened in such climates and well worth the effort – living walls have the potential to transform even the hottest of places into something truly special.

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