More living walls are being created in cities to tackle pollution, but keeping them alive can be a major challenge

This article is more than 1 year old

This article is more than 1 year old

When Andrea Carnevali’s son started at St Mary’s Catholic primary school in Chiswick he was alarmed to find that pupils were sometimes kept indoors at break times, despite a large playground.

The reason was the nearby six-lane A4 road, which has up to 100,000 vehicles thundering past the school each day. As evidence mounted about the impact of poor air quality on children’s health, the headteacher restricted time outside.

Carnevali and other parents decided to take action. Within months they had crowdfunded almost £100,000, and last month a 126-metre “living wall” of 12,000 plants was installed as part of a clean-air initiative at the school. They hope the wall – designed to trap exhaust particles, absorb sound and increase biodiversity – will transform one of London’s most polluted schools into one of its greenest.

“We’re immensely pleased,” said Carnevali. “The council is monitoring changes in air quality, and we hope for a 40% improvement – but even 10% would be good.”

St Mary’s living wall is one of many being installed around the country by local authorities and private developers. Tennis fans may have noticed two enormous living walls flanking the giant outdoor screen at this year’s Wimbledon championships.

Facebook Twitter Pinterest The stunning vertical garden on south London’s Elephant & Castle underground station. Photograph: Simon Turner/Alamy

And they are increasingly a feature of hotel and retail developments. A stunning vertical garden graces Elephant & Castle underground station in south London, part of a plan to improve air quality at one of the capital’s busiest road intersections.

In a variation on a theme, “living lamp-posts” were installed this month as a trial in Ebury Street in Belgravia, central London. They will be monitored for air quality improvement for a year; if the pilot is successful, it could be extended to some of the other estimated 494,000 lamp-posts in central London.

In Hull, the council is considering a proposal to transform Whitefriargate, a historic thoroughfare now blighted by empty shops, with vertical gardens.

“Demand is definitely growing. There’s been a steady rise in interest over the past two years, and a noticeable increase since the beginning of this year,” said Calvin Dalrymple, a living wall consultant with ANS Global, one of the country’s leading suppliers, and the creator of St Mary’s living wall.

“It’s being mainly driven by local authorities, but also a greater awareness in the private sector of the need for sustainable architecture.” According to Benz Kotzen of the Green Roofs and Living Walls Centre at the University of Greenwich, “we need every tool to try to improve things, and there just isn’t enough capacity in urban environments to create green infrastructure at ground level.

“It’s no longer good enough to have a building facade that just keeps out the weather. In the future, building facades will need to be much more functional – cleaning the air, collecting energy and improving biodiversity.”

Vertical gardens could also be used to grow food, he said, adding that herbs, strawberries, tomatoes and rocket did particularly well.

Living walls range from simple wire structures to support climbing plants to sophisticated modular systems, using soil or hydroponic manmade substrate, and solar-powered irrigation. The cost ranges from £200 to £800 per square metre.

The main challenge with maintenance was working at height, said Kotzen. “Growing plants vertically is no more difficult than horizontally, but all gardens need maintaining.”

Not everyone is a fan of the trend towards vertical gardens. “They’re not a solution, except for the wealthy,” said Mick Crawley, professor of plant ecology at Imperial College London. “There are much cheaper and more effective ways of improving air quality.” Local authorities struggling to pay for essential services would be better advised to plant trees, he said.

London’s first living wall, installed in 2005 by Islington council at a children’s centre at a cost of £100,000, withered and died within four years after the irrigation system failed.

Facebook Twitter Pinterest Lucy Dunhill’s artwork showing how Whitefriargate in Hull, which is blighted by empty shops, might look.

“Living walls will die if they’re not designed properly and maintained,” said Dalrymple. “There are four key things to longterm sustainability: correct water management, correct substrate, maintenance and plant selection taking into account shade, wind and elevation.”

With between 28,000 and 36,000 deaths in the UK each year attributed by Public Health England to long-term exposure to air pollution, living walls are expected to become more common. But the benefits go beyond improvements to air quality.

Lucy Dunhill, who is behind the Hull proposal, said: “Visually, Whitefriargate is very depressing, with boarded-up shopfronts and very bad acoustics. Your eyes are not drawn up, you keep your head down when you walk along Whitefriargate.”

Her green walls plan will, she hopes, “become an attraction in itself as well as improving the environment”.

Andy Wayro, landscape design manager at the All England Lawn Tennis Club in Wimbledon, said its living walls were aesthetically pleasing, had reduced noise and connected people to nature. “The feedback from players and the general public has been really positive,” he said.

At St Mary’s in Chiswick, children have been planting a section of the wall with wild strawberries, thyme, rosemary, sage and lavender, using wooden markers to allow them to monitor growth.

“The children adore it, and so do the teachers,” said Carnevali. “Apart from any environmental benefits, they say it makes them happier and calmer.”