Green walls can also be great marketing tools according to retailers who install them. The Village Goldsmith commissioned a large 5m x 3m green wall in its new downtown Wellington store and it's better than a neon sign according to owner Ian Douglas. He says that, without exception, people comment on how much they love it. Douglas also adds that it's one of their favourite aspects of their new fit-out, saying that in terms of advertising, it's better than a flashing neon sign!
The psychological benefits of including plants in the indoor environment have been known for a long time think of the Victorians and their leafy conservatories. However, little scientific research on their environmental and health benefits had been done until the 1980s, when NASA conducted a series of studies.
NASA's principal investigator researching air quality on space stations, Dr William Wolverton, found that on top of absorbing carbon dioxide and releasing oxygen, as all plants do, many houseplants can help to naturally remove toxic substances from the air such as formaldehyde, benzene and trichloroethylene, which are common in modern buildings.
This is an important benefit as, according to recent studies, indoor environments may be as much as 10 times more polluted than outdoor environments.
Because a minimum density of plants per cubic metre of air is required to effectively filtrate the air, green walls provide an excellent solution to this problem. Green walls contain 25 to 40 individual plants per m², thus providing the capacity to filter a large indoor area without taking up valuable space with planter boxes, and pot plants.
Two well-known air cleaning work-horses are Peace Lilies (Spathyphyllum spp.) and Flamingo lilies (Anthurium spp.) as well as Rabbit's foot fern, (Davallia fejeensi) and Button fern (Pellaea rotuntifolia) to give an area a natural fresh forest smell.
As well as being a natural air-filtration system, interior and exterior living green walls function to cool the air in the warmer summer months by a process known as evapotranspiration. In fact, exterior living green walls can reduce wall surface temperatures by as much as 10ºC, resulting in significant energy savings and air conditioning costs, but also helping in cooling buildings and cities down.