While still a relatively new concept for specifiers in the UK to consider, the use of green walls as a sustainable building solution continues to grow rapidly, with a wide range of aesthetic, thermal, environmental and cost benefits on offer to architects, building owners and facilities managers. By Justin Errington, director of MMA Architectural Systems Ltd
Over the last two decades, a range of modern systems and techniques have been developed which provide the aesthetic appeal of a green facade while enhancing a building’s operational performance. Modular compost and hydroponic systems are two such options, both of which have been used in a number of projects to provide an ‘instant’ green wall.
However, an excellent alternative to these heavier and more costly modular systems is the use of lightweight stainless steel systems, which not only deliver comparable long-term benefits, but are also much more cost effective and provide some unique, material advantages.
These systems use a combination of high grade stainless steel wire ropes, rods and mesh products to provide a robust, elegant and long-lasting structure that supports plant growth on building facades. The use of marine-grade stainless steel also gives assured quality for the life of a building (making the systems suitable for even the harshest environments, including coastal applications) and their light weight makes them easy and fast to install – and immediately able to support new plants which are planted on-site (typically for a square metre of fully-established plant coverage, a stainless steel system weighs only 20-30kg when planted).
Conventionally, plants are grown up green wall systems, but given the requirements of individual projects, they may also be planted to cascade down the structure (i.e. grown from the top down), or from planters installed at strategic points up the facade. Routine horticultural maintenance is necessary to maximise the life of the wall and to realise its full potential, but whether grown from the top or bottom, maintenance is simple and straightforward and is carried out predominantly at planter level. If necessary, plant replacement is also a simple task.
Through the use of these products in combination, architects can achieve a wide variety of designs on the vast majority of building structures, including curves and intricate shapes to meet their overall design objectives. Well designed and well maintained green walls significantly enhance a building’s appearance – whether it’s to add a new aesthetic dimension, disguise a car park, refresh a tired facade or add colour and texture to a wall.
Used on appropriate elevations (and suppliers of these systems are generally very happy to work with architects at every stage of the process to ensure that the right system is specified to meet their needs) green walls can deliver a number of significant operational advantages.
They can certainly help to improve energy efficiency and reduce energy costs by providing an additional layer of insulation in the winter and acting as a screen to the sun in the summer. Acting as an insulation layer in this way not only delivers thermal benefits, but also acoustic ones, with green walls able to absorb sound and so improve the living and working environment of the building’s occupants and their local environment.
In urban areas, the structures help to improve local air quality by absorbing carbon dioxide, trapping dust and other harmful pollutants such as PM10 and releasing oxygen. If graffiti is a particular local problem, green walls can provide an excellent deterrent, making the application of graffiti directly to the building structure almost impossible. The introduction of plants to the local environment also provides an ideal habitat for new or displaced wildlife, improving bio-diversity by providing new habitats for birds, bugs, bees and flora. If required most manufacturers can advise on the optimum planting scheme and also help with the introduction of appropriate flora and fauna.
The walls also help to protect the facade of a building, extending its life by acting as an effective shield to weather and helping to protect it from damaging UV light.
Stainless steel green wall systems not only offer these sustainability benefits, but are also energy efficient in production, accounting for very little embodied energy per square metre of building. The system, unlike some others, is also completely recyclable at the end of its useful life.
While these systems are not installed with full plant coverage, well designed systems provide elegant aesthetics from the time of first installation – even before the planting scheme has fully matured. With careful design, the materials used in combinations provide an array of design options, offering the addition of texture and geometric patterns to a building’s facades and providing interesting shadow definition. And while the plants are maturing, these systems can provide an interesting aesthetic structure allowing the building’s occupants and their neighbours the chance to see the wall evolve and fully develop.