Living walls in the urban arena

The concept of greening buildings has enjoyed a renaissance as society looks to develop a cleaner, more pleasant and sustainable way of living. In fact, living walls are moving indoors...

Adding foliage to buildings is not a new concept. The greek historian Dionorus recorded a technically detailed description of the Hanging Gardens of Babylon which described how the garden was built on tiers with vaults which carried the weight of planting; he even described the waterproofing system used for a green roof substantial enough to support trees. However, in recent years, the concept of greening buildings has enjoyed a renaissance as society looks to develop a cleaner, more pleasant and sustainable way of living.

Living walls deliver a range of benefits beyond the obvious and stunning aesthetic. Some benefits are obvious and need little explanation, such as the ability of foliage to remove carbon dioxide from the air and to exhale oxygen via photosynthesis. However, foliage also improves air quality by removing particulates, and unlike trees, foliage on walls does not impact drastically on footprint or restrict air flow and helps to reduce ambient temperature in the urban environment.

Few external cladding systems can match the ability of living walls to fundamentally change a building’s appearance. Traditional mechanical cladding systems, such as metal, glass and bricks, are supplied in an endless range of colours and finishes to offer the designer a broad palette with which to be creative. However, a living system changes a building exterior from something which is inanimate to something which lives and breathes, changing with the seasons, constantly growing and even moving with the weather.

Apart from the aesthetic and environmental benefits, living walls and Green Screens also offer a surprising range of uses in the private, public and commercial spheres. Schools and other public buildings are increasingly using living systems, while many local housing authorities are realising the benefits of easy-to-install, sustainable Green Screen boundary systems which are delivered pre-grown and which adhere to boundary Building Regulations. Living walls and Green Screens are also being used by local authorities as a deterrent against anti-social behaviour such as graffiti and Green Screens are also being installed alongside highways to improve road safety.

However, the market for living walls has, in recent years, been somewhat tarnished by doubts about the reliability of systems following to the failure of a few high profile examples. But the logic behind criticism of the concept of living walls is flawed. It is akin to claiming that cars are not a good idea because Toyota made some mistakes in 2009. It fails to take into account the development of successful modern systems which are tried and tested and which are extremely efficient.

Perhaps the best example of a European living wall exists in Monaco; a surprisingly harsh location for living walls as Monaco is water-impoverished and with a hot, sunny, marine environment. Yet the WallPlanter living wall in Monaco’s Avenue Princesse Grace has thrived since it was first installed in 2006. The south faced wall fronts on to the sea and is bathed in strong sunlight throughout most of the year with temperatures reaching an average high of 80o F in August, and an average low of 43o F in winter. Precipitation averages 31.7mm a year, which contrasts dramatically with 611mm in London.

In London a fine example of a living wall can be found at the O2. The site owner had a need for a barrier to shield visitors from construction work on a nearby housing development. Mobilane supplied a simple living wall system which was installed on an open steel structure. The 150m long, 8m high wall took just over a week to install and requires minimal maintenance. Four years after installation the wall remains impressively verdant.

These and other successful living walls go largely unnoticed, which is to be expected. ‘Living wall continues to thrive’ is nowhere near as good a headline as ‘Living wall fails’.

The secret for designers thinking of specifying a living wall is to speak to the supplier and to ask to see examples of previous systems. This is, unfortunately, a relatively standards free marketplace, so designers need to do a little extra work to check that suppliers can deliver on reliability and post-installation maintenance. All living systems need maintenance, from the humble office spider plant which needs to be periodically watered and fed, to full blown living wall systems. But the latest state-of-the-art living wall systems feature automated monitoring watering and feeding systems and require minimal inspection and maintenance.

The latest development in living walls sees them moving indoors. The new LivePanel Interior wall system (a development of the successful exterior system) is suitable for a wide range of building types, including offices, call centres, hotels, leisure centres, retail and business centres. The system is easy to install and requires no building alteration work prior to installation. All that’s needed is a plain wall, suitable lighting and an electric power socket. A basic system can be installed in a single morning.

The benefits of plants in offices and other public spaces are widely recognised. Surprisingly, the air inside a building can be up to nine times more polluted than outside due to emissions from electrical equipment, paint, and furniture, which can be compounded by inadequate air conditioning and ventilation. Plants combat this by removing carbon dioxide (which lowers work performance), as well as particulate pollutants and volatile organic compounds (VOCs) and help to balancing humidity. The psychological effects of plants indoors are also well understood and research has shown that interior plants can reduce stress, improve health, affect mood and increase productivity in the workplace.

The LivePanel interior system features a built-in computerised irrigation system and specially developed nutritionally balanced minerals substrate to support vegetation. The system can support a wide variety of plant types, depending on available lighting and level of maintenance needed. Maintenance is minimal and once a month the system is serviced and the water and feeding levels are tested. The reservoir will be adjusted accordingly if required. The system takes up little space, but the effect is stunning.

We will increasingly see more living walls in the urban environment, both indoors and out, just as we have seen a dramatic increase in the number of living roofs. There is some work to be done to combat cynicism, but the future is definitely greener, in the most literal sense of the word.

[this article appeared in the Nov/Dec issue of Eco Building Magazine]

Lack of standards is ruining the reputation of living walls

A lack of regulations and standards is to blame for a commonly held belief that living walls are problematic. Sean Farrell of living wall supplier Mobilane explains why.

While the concept of adding foliage to buildings is an old one - the greek historian Dionorus recorded a technically detailed description of the Hanging Gardens of Babylon - the modern market for living walls is relatively new, yet it has suffered some negative publicity due to the failure of a few high profile examples. These have been pounced upon by critics who have claimed that living walls are both vulnerable and cannot be considered sustainable due to the watering and feeding requirements. These criticisms are wrong and the logic behind them is flawed. It is akin to claiming that cars are not a good idea because Toyota made some mistakes in 2009. It fails to take into account the development of successful systems which are far more efficient and sustainable.

The sustainability criticism is flawed because it fails to consider the green benefits against physical footprint which living walls deliver. For example, if you have a cube shaped building – a square plan and 4 square walls - with all four walls and a roof which are all greened, then that building will have a green ‘footprint’ which is five times the physical plan size of the building. Or to look at it another way, if the building were demolished and its footprint given back to nature, it would still not match the same area as the entirely greened building.

While it is a nice idea that areas of our towns and cities are given back to nature, the reality is that we need all those buildings and roads. There simply is no way that we can realistically introduce sizeable new green spaces in built-up towns and cities when we are already pushed for space. The government’s controversial push for expansion into the countryside reveals just how unrealistic it is to think about returning urban areas to green land. If we are going to add greenery to towns and cities, we have to look at adding it to new and existing buildings, both roofs and walls, that means going up the sides of buildings, and across the tops of them.

The sustainability of a living wall also depends on the efficiency of the system itself and the substrates used. The best modern systems are highly efficient, using low energy sensors to deliver only the exact amount of water required by the plants with no wastage.

However, while the environmental and social benefits of living walls are well understood, living wall systems, screens and living roofs are relatively free of regulatory frameworks and concepts which apply to most other parts of the building envelope, and there are no nationally recognised performance standards in place to reassure the specifier interested in adding greenery to buildings. Designers and specifiers are having to trust living wall suppliers’ claims on the performance of their systems and do not have minimum standards to guide them.

The Government and construction industry has, for many years, been committed to a programme of sustainable and more efficient construction. During this time Building Regulations have become increasingly onerous and there is a myriad of performance and quality control criteria which apply to the vast majority of building products and systems. This has been welcomed by manufacturers and suppliers and as a result the envelope is being pushed when it comes to research and development. Insulation systems, cladding systems, waterproofing systems etc, all have to meet minimum standards to exist in the marketplace and to be competitive. However, living systems such as green walls do not currently have the same requirements.

With no minimum standards in place, and no strong regulations governing the marketplace, suppliers of living systems are free to take systems to market which have not been properly tested and which are not fit for purpose. The result is a marketplace which has seen several high profile failures and in which good systems and good suppliers are being tarnished by the failure of bad systems. It is hardly surprising that living walls are viewed with some suspicion in some quarters, but living wall systems are incredibly important and offer many environmental and social benefits. It is a tragedy that development of the market is being hindered in this way.

Yet it is a market which is developing at a phenomenal pace. The latest living wall systems offer designers a phenomenal design palette and support a huge range of plant types. The external living wall has even moved indoors and it is now possible to have a LivePanel interior wall system installed within a building in less than a day and with no need for alterations to the building fabric. All that’s needed is a blank wall and a power point. The effect is stunning and the benefits to users of public sites such as airports, offices, shopping centres cannot be overstated.

As for the longevity and robustness of exterior living wall systems, there are many examples where the best systems have been thriving for many years. For example, the 150m long, 8m high living wall system at the O2 arena in London which four years after installation continues to thrive with minimal maintenance. The system took a little over a week to install and has not lost a single plant. There are also other excellent examples, such as the impressive living wall installed at Kendal College in Cumbria, the wall at Parkside Hospital in Wimbledon, the Mercedes Research and Development Plant, and a stunning wall at Monaco (surprisingly a harsh, water impoverished marine environment) which six years after installation is still regarded as the best example of a living wall in Europe. All of these installations thrive silently and without fuss, never drawing attention to themselves but always drawing admiration.

Maintenance of living walls is an important consideration and reflects on the lifetime cost of a wall. But the best suppliers will offer competitive maintenance packages.

Until such a time when minimum standards are introduced, designers and developers who are interested in specifying living wall systems need to ensure that suppliers they are speaking to can illustrate their heritage and can prove their systems perform as stated at a fixed price with guarantees for planters. At Mobilane we are able to show photos of progression of growth over 6, 12 and 18 months, as well as examples which continue to thrive after many years. Specifiers should also ensure they choose suppliers who can offer maintenance systems to protect their investment. In our opinion, green walls should not need replacing every four years, they should last a lifetime.

[This article will appear in a future issue of fc&a magazine]