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]