Posted on January 29, 2016
There’s no need to restrict planting to the ground.
From the smallest house to the biggest development, bringing the walls to life can have surprising benefits The urban green revolution is all around us. From floriferous balconies to lush roof gardens, green walls and innovative urban food-growing schemes, the plant-love in our cities continues to grow.
And rightly so. Every tiny
patch of planting brings a benefit to those who live and work there. A
challenging world of flash floods and unforgiving, heat-baked concrete is
transformed by foliage-dappled sunlight and fresh scents. Through a host of
small utopias, cities can become an ever-changing palimpsest of greenery. The evidence is overwhelming. Vegetation in cities
helps regulate air temperature and combats air pollution by trapping particles
on leaves. It also reduces local flooding by absorbing rainwater, both at root
level and by holding it in the canopy of foliage, while planted areas are known
to increase local biodiversity. On a domestic level, few need convincing
but, if the warm glow of environmental rectitude is not enough, there are also
good business reasons to seek out an urban greening specialist. Foliage on or
around a building acts as an insulating jacket which keeps the building warmer
in winter and cooler in summer. This not only reduces carbon emissions but
saves on heating and air-conditioning bills.
There are also human
benefits, such as improved mental health and reduced stress. “You will get
things from a green building that you won’t get from a conventional green
space,” says Gary Grant of the Green Roof Consultancy, who designed London’s
largest green wall, at the Rubens Hotel in Victoria, London <video > “It
is better for the people using it and the building is more attractive so, for
example, if it is next to a restaurant, then you get a busier restaurant.
“One of our clients discovered that it reduced staff turnover. Companies think about saving pennies by changing to low-energy light bulbs, but the money spent making their workers more comfortable or putting a spring in their step ends up having a major financial benefit in terms of reduced recruiting costs.”
Towering six stories over the busy street below and covering an area of 350 square metres, the living wall at the Rubens contains more than 10,000 plants from 23 species, including evergreen ferns, ivy and flowering plants such as geraniums, crocuses, buttercups and strawberries. Installed and maintained by expert urban greening company Treebox, the wall is checked at least four times a year. In the meantime, a rainwater-collection system on the roof, text-alarmed in case of failure, stores up to 1,200 litres of water to irrigate the planting modules.
Designed to create drifts of color throughout the year and provide forage for pollinators, the vertical garden imbues a once featureless façade with charm and personality.
Green walls are, however, not always welcomed and there are frequently objections from people who have reservations about the amount of money that will be spent
“In the context of construction, the cost is minimal and the benefits are considerable,” he adds. “A green wall will protect the underlying structure from frost, sun and rain and will extend the life of the building. Ultra-violet light is very destructive. Stone does very well in the face of UV exposure, but plastics decay, waterproofing fails. “Green installations could double, or triple, the life of the surface to which they are attached.”
As with anything, green installations have a design lifespan. The hardware does not last forever and the plants must be periodically managed or replaced, yet Gary is adamant that the numbers stack up.
In addition to the hardware and engineering, large urban greening schemes require a fair bit of gardening know-how, not least because they are far more exposed than conventional gardens. “It is amazing how many things do grow,” says Gary. “But a lot of people in construction don’t really get it; they want to buy a product that you can just roll out and it is finished. It is not like buying wallpaper; there is a need for horticultural and architectural skills.”
As vertical greening becomes more popular and more ambitious, the horticultural industry, too, must adapt to its demands. The palette of proven plants is likely to increase, but sourcing can be an issue.
“I might be looking for plant diversity, functionality or pollinator benefits,” explains Gary. “Some nurseries are responsive and say, ‘We can do that if you can wait a little while,’ but many large growers just want to shift stock. This is a problem when you are implementing a project. You have to install what you can get hold of.”
Also there is the matter of manpower. Horticulture has an image problem: gardening is often seen as something done by old men and the breadth of career options is poorly known. As a result, the workforce is ageing and nurseries struggle to find enough young British employees with sufficiently good skills. And it seems unlikely that the ability to abseil off the top of a building to plant up a green wall was on their selection criteria.
“There is work to do,” admits Gary. “Horticultural professionals are not as well respected as engineers or architects in Britain. Countries like Germany are way ahead. A potential lack of skilled horticulturists is a problem, but I am very optimistic. I think we should stimulate a market and then stimulate investment in training.”