Green walls, or vertical gardens, are vertical faces of buildings or other structures that integrate vegetation to its surface either in whole or part. They are an interesting way to maximise greenery in tight urban spaces and has been often used in large projects as well as finding a home in smaller commercial projects.
The greening process has certainly breathed a new aesthetic into buildings as varied as houses to work environments. And by “new” we mean new if that concept ignores the previous 2,600 years. One of the original 7 wonders of the world – the Hanging Gardens of Babylon – in 600 BC is the earliest known example of a green wall. Today’s vertical gardens even use an irrigation concept similar to that of the then-King Nebuchadnezzar II. As far as can be ascertained, the modern version using hydroponics was invented by Stanley Hart White in 1938 and not being ‘un-capitalistic’ he even patented the original green wall!
Green walls have been called vertical gardens, biowalls, or VCW V (vertical vegetated complex walls). Fundamentally though they are all the same thing. They are a way of maximising the sustainability of the planet and reducing the energy load on buildings.
There are two main classes of vertical gardens: green façades and living walls. Green façades are made up of climbing plants either growing directly on a wall or on specially designed supporting structures. The plant shoot system grows up the side of the building while being rooted in the ground. A living wall is comprised with modular panels or containers, often of stainless steel, as well as geotextiles, irrigation systems, a growing medium and vegetation.
In offices and other commercial environments, for green wall to be installed successfully requires extensive irrigation systems. Sometimes they are attached to the air-return of the ventilation system to be used for air filtration. Vertical gardens are found most often in urban environments where the biowalls reduce the internal temperatures of buildings. Due to transpiration in plants, it is known that the surfaces of the walls do not rise more than around 5°C above the ambient temperature.
For smaller green walls the plant containers are often re-purposed – items that had a previous life – such as milk bottles and cartons, rain gutters, wooden palettes, crates, even disposable styrofoam coffee cups can be used for the seedlings.
Unlike the more traditional “recycling,” where materials are downgraded and then processed for reuse, up-cycling is converting both common and uncommon waste into new products of improved quality and environmental value. This act of repurposing has less impact on landfill.
Things to think about when considering a vertical garden:
- Appropriate plant selection
Plant size, type, and plant requirements growing in confined spaces. Greater varieties of plant species can be used aand adds more visual itnerest.
The ability to place the plants in vertical position for natural growth and reduced plant stress
- Soil volume
Must be appropriate to the plant selection.
- Drainage and irrigation
Both the drainage and irrigation should be built-in and integrated with the containers and structure, plumbed up and must efficiently remove excess water.
By reducing the runoff by capturing water from the irrigation system will improve the water efficiency of the vertical garden and minimise leaching into other plants below.
- Integrated water storage
Plants should be able to access water stored at the base of the container.
- Easy Maintenance
This is critical – access must be made easy to insert new and remove old plants, rearrange plants, and to maintain the plants. In addition, maintenance will be required for the structure and drainage and irrigation lines.
Sometimes green walls just appear over time – buildings covered in ivy but managed over time. Frensham in Mittagong in the Southern Highlands is just that.
Vertical gardens have been designed for urban agriculture, urban gardening, because a wall can be made more attractive, and sometimes it is built indoors to help alleviate sick building syndrome.
What do you think – would you like a green wall in your house or workplace? Let us know below.