What Are “Living Walls” and How Can They Improve Air Quality?

Last month, an 80m² “living wall” was unveiled at a Mayfair development site owned by property group Grosvenor. The wall, which consists of wild grass, flowers and fruit embedded into a scaffold, is hoped to help curb emissions by as much as 20%.

Though the St Mark’s building wall (found on North Audley Street) is one of the first of its kind, the idea itself has been floating around environmental thinktanks and laboratories for a while. Here’s a closer look at what exactly living walls are, how they can help the environment and what the obstacles are to their widespread adoption.

How do living walls work?

With roughly 4,000 Britons dying in London alone as a result of respiratory and cardiovascular complications, air quality is understandably a growing concern in the capital and abroad. The UK government have proposed a number of measures to try and clean up the city’s airways, including the introduction of Ultra Low Emissions Zones (ULEZs) and the phasing out of older vehicles.

However, with a problem as complex and far-reaching as air pollution, a flexible approach is key to solving the challenges it holds. For that reason, much has been made of the huge potential of so-called living walls, which have the ability to actually take out some of the pollution that is already lurking in our atmosphere (rather than just limiting future emissions).

This works via a process of absorption. Harmful contaminants such as particulate matter 10 (PM10) and nitrogen dioxide (NO2) stick to the leaves of vegetation, thus removing them from the atmosphere and cleaning up the environment. With this huge benefit in mind, Grosvenor has included the addition of living walls in its ambitious plans to cut emissions from all of its buildings by 50% before 2030.

The pros and cons

As well as reducing emissions by as much as a fifth (depending on the size of the surface area), living walls have also been hailed as carrying a number of other benefits. For example, the density of the foliage is expected to act as a muffler and bring down noise pollution by as much as 10 decibels, as well. In addition to this, inbuilt sensors and monitors can provide a further solution to the challenges of local air quality monitoring.

Meanwhile, they’re also thought to provide a habitat for a variety of insects and invertebrates, thus increasing local biodiversity, whilst also bringing an aesthetically pleasing aspect to the facades of areas undergoing construction.

“As the estate continues to adapt and evolve we want to ensure that the impact on the community is positive,” explained Mark Tredwell, development director of Grosvenor. “As well as reducing air pollution, we hope the living wall will introduce a rich biodiversity to Mayfair and encourage people to linger in the area.”

On the other hand, the long-term effects of the walls are as yet unknown. While pollutants may be removed from the atmosphere short-term, rainfall could theoretically wash the contaminants off the foliage and back onto the city streets, thus creating a cycle of pollution. What’s more, the actual return-on-investment in terms of financial outlay is still unclear. Therefore, more tests are needed to confirm the value of living walls – but the early signs are certainly encouraging.