There is something incredibly exciting about living walls. Stacking green plants on the vertical plane on buildings, where you’d think they just should not be, goes against the odds. Yet nowadays they are almost commonplace, and most people have encountered one somewhere. They cling to life with extraordinary tenacity, usually in a growing medium only a few centimeters thick, with water fed via irrigation pipes. Cynics may criticize and some walls are without doubt better designed and maintained, or use a better system than others, but we should applaud this urban green trend, and encourage it. We need it. Modern systems are reliable and use very little water or energy to run.
As a global society we are going through unprecedented changes; now more than 50% of the world’s population is urbanised and this will grow to 75-80% by 2050. Most of those people are essentially disconnected from Nature. It is now recognised that we have an innate need, called biophilia, to maintain our relationship with Nature. Not surprising really, when you think how we have evolved, yet the psychological and physical cut-off, over the last 100 years, has been astonishing. This can only become more pronounced as cities continue to swell, and highly-stressed people produce dysfunctional societies. If we can green our urban streets then perhaps we can counter this negative effect. Green walls take up almost no footprint in the urban landscape, not even a pavement width. All that is needed is a supporting wall and we have plenty of those. Trees are beautiful and add huge amounts of biophilic interaction into a citiscape, but we find them increasingly difficult to site, due to underground services and growing space needed. Those of you who read my blog will know that I also consult on trees, so I love them dearly, but I see living walls as having a different role to play and as being more versatile.
Living Wall in a small courtyard garden by Vertology
Living walls have physical benefits on the environment too. They provide a haven and food source for insects, especially bees. Birds find seeds, berries and of course, insects on the wall and smaller birds are known to nest amongst the foliage. Living walls are also helpful in mitigation of air pollution; I was involved with designing and plant selection for a wall put up by Transport for London (top picture) to test the ability of plants to capture pm10 – airborne particulates, primarily from diesel engines. Whilst we need to remove the source of these pollutants, capturing them is a good secondary strategy. It turns out that walls in a street canyon (where the building height is greater than the street width) cause the air to move in a cyclical manner, so air passes through the foliage of a living wall several times. Trees can do this, but dense canopies can actually trap particulates down at street level, concentrating them where people are. Most trees also are deciduous, so have no such benefits in the winter months.
Interior Living wall in Norway, installed by a Vertology partner
We can bring living walls into the interior, and in fact in hostile climates, that’s where you’ll find most of them. Whilst I have designed outdoor walls in climates as diverse as Dubai, Norway (Trondheim, 62° latitude) and Chicago, in such places it is often easier to put your dose of biophilia indoors! We spend 80-90% of our time inside, so this makes sense. Such walls also clean the air. Much quoted studies by NASA have shown that a range of common houseplants (which are basically plants of a sub-tropical origin) are efficient at removing Volatile Organic Compounds VOCs, such as formaldehyde) from the air. These can be found in concentrations far higher than outdoors, due to the nature of air recirculation and energy conservation. So we bring the jungle indoors, where we live and work.
Walls have the most drama when they are large, but they don’t have to be. Small walls in intimate spaces still have a large impact. This can be a home, courtyard, rooftop or office reception. Small is beautiful.
A small indoor living wall by Vertology
Having worked extensively with living walls over the last decade, I now consult, design and install them worldwide via my company Vertology Living Walls, and its approved partners. Grab yourself some biophilia – install a living wall!
Posted in Biophilia, Design, Dubai, UAE, Ecosystem Services, Green walls, living walls, Retail, Vertical Greening Tagged with: biodiversity, biophilia, eco-system services, Edgware Road, green walls, Indoor green wall, living walls, UAE, urban greening, Vertical Landscapes
I have been asked what it costs to run a green wall; often, people imagine extreme costs and infra structure, so think a green wall can’t be justified on those grounds alone. The fact is, early systems were highly consumptive of water and electricity (ie felt based systems) but modern systems are not. I base the following on the Biowall system, because that is what I know; this was a case study done on the wall I designed at Edgware Road for TfL:
Green Wall at Edgware Road
Water & Power Consumption
To realise the on going benefits of the wall there are a number of necessary inputs. The two inputs that are often raised as a concern are water and power. The following calculations confirm the minimal amounts required by an efficient living wall system:
The unique design of the hydroponic Biowall system provides fully comprehensive planting at an average of 1 litre per m2 per day. This is by far and away the least water use of any of the living wall systems available today. Note: traditional summer ground planting in beds requires 3 to 4 litres per m2
200m2 x 1 litre per day x 365 days = 73m3 of water in a year.
At an average supply rate of £1.50 per m3 this gives an annual water bill of £110.00. If this is harvested rainwater then there is not supply rate but there are extra installation costs.
Remote sensing and remote control irrigation system allow fine tuning of the system. To keep the wall flushed through, 10% of what is put onto the wall comes off the bottom and goes to drain.
7.3m3 of water going to drain at an average charge rate of £1.00 per m3 gives a drainage bill of £7.30
The irrigation system is driven by a 4bar pressure pump rated at 0.8kW.
There are three irrigation zones on the wall at Edgware Road and during the summer months each zone may operate for up to 9 minutes per day. During the winter months this will reduce to approximately 1 minute per day. An annual average of 4 minutes per day per zone is expected.
4 minutes x 3 zones x 365 days = 4,380 minutes of pump use per year
This equates to 73 pump hours per year. 73 x 0.8 = approximately 60 kWh annually. At an average supply rate of £0.10 per kWh this equate to electricity usage of £6 per year.
Exclusive of standing charges, the overall annual costs for water, drainage and electricity for this 200m2 wall is therefore expected to be £123.00
Therefore guideline running costs for a living wall (excluding irrigation and horticultural maintenance) can be assumed to be less than £1 per m2 per year.
I now run a new company Vertology Living Walls and have an advanced, patent-pending green wall system, Viridiwall™ which improves further on the Biowall system.
Posted in living walls Tagged with: Edgware Road, green walls, living walls
Last year some interesting work emerged over the use of green walls for mitigation of air pollution; in particular the ability (or otherwise) of plants to remove particulate matter from the air, with pm10 being the size range focussed upon. This is the particle size most emitted from diesel exhaust, and this does a lot of damage when breathed in.
Like many cities, London is constantly breaching WHO and EU pollution limits and has the threat of a 300m euro fine being levied. Of course, the pollution is nothing like that in the news recently from Beijing, which is largely caused by the low quality coal that fires their electricity generation plants, coupled with cold winter air, which traps pollution in.
So the Mayor’s office set up the Clean Air Fund, and put £5m into research – a tiny amount compared to the fines, but better than nothing. A tiny amount of that was used to put up initially one, then two green walls, which were to be monitored by Imperial College London to see what types of plants trapped the most particulate. Biotecture put the first (and principle test wall) up for transport for London on the side of Edgware Road tube station, right by the Marylebone flyover, one of London’s worst pollution hotspots. The second one was added rather later at the Mermaid Theatre and was done by ANS.
The Green Wall (designed by me) at Edgware Road
I chose 15 species of plants which I knew would take the South facing aspect of our wall and which had smaller leaves – research told me that smaller, hairy leaves were the most effective at trapping particulates, and made sure the species were present across the whole height of the wall. Past research in Germany on Climbers had shown that plants trap more particulates at height, around the 4-5m mark. As it turned out, UCL only collected leaf samples from the pavement level, despite there being roof access where some sampling could be taken, and they only did this for about nine months, so I feel sure that the sample results are insufficient. Nonetheless, they showed a definite ability to capture particulate.
We have barely scratched the surface and what’s needed now are sustained and serious trials to gather more comprehensive results under widely varying conditions and climates… sponsors anyone?
Posted in Design, Environment, living walls, Sustainability Tagged with: Edgware Road, green walls, pm10, pollution entrapment, TfL