Can vertical gardens be incorporated into our cities?

Written by Elena Collins on 25 October 2012

From the living wall at Vancouver International Airport to the Quai Branly Museum in Paris, by French botanist Patrick Blanc, low-maintenance green walls are being used not only as an attractive but practical alternative to cement and glass. Whilst the latter materials are often criticised for being unsustainable building products, their green counterpart has proven to reduce heat loss from buildings and improve air quality.

Quai Branly Museum

Research by the Centre for Sustainable Development at Cambridge University found living walls and green roofs cut the wind chill factor by 75% and heating demand by 25%, with just one layer of vegetation. The plants can save thousands of pounds in reduced heating and cooling as well as reducing CO2. Furthermore, green walls provide homes for insect and animal habitants, which improves urban conditions. The benefits ranging from evaporative cooling, air purification and sound control are all evident from the vertical garden at the Vancouver International Airport. The 17 metres high and 11.6 metres wide wall, designed by Sharp & Diamond Landscape Architecture, is home to over 27,391 individual plants selected for their long-term performance on 2,107 panels.

There are drawbacks, however. The three main problems include weight, maintenance and public perception. Firstly, to add a biowall to a large civic or commercial building, a structural engineer needs to determine if it can support the plants, planting medium and water. Secondly, the garden will need to be sustained. Without a proper plan, a living wall could easily grow out of control or die if left untreated. Garden designers must also find a substance to mimic soil, which is light and lasts. Finally, the biggest challenge for the vertical garden is public perception. Often plants that overcome the previously two issues are deemed as unattractive, resembling weeds. 

A shopping centre near Milan has recently opened and become the biggest vertical garden in the world. The huge garden covers a surface of 1263 square metres with a total of 44,000 plants and is made up of small metallic containers, making the garden more expensive than classical methods. At a total cost of 1 million euros, this feature might be environmentally friendly, but not economically sustainable. So It terms of real estate, are vertical walls a good investment?

Vo Trong Nghia
Stacking Green. (C) Hiroyuki Ok

In spite of the costs, the beautifying of buildings is increasing in popularity. Many architects are opting for green facades even one a small and domestic level. In Vietnam, architecture firm Vo Trong Nghia were recent winners of the House Category at World Architecture Festival and shortlisted for the World Architecture News Effectiveness Award for the house Stacking Green. The 4 metres wide by 20 metres deep home uses green facades across the house to contribute not only to visual comfort of the inhabitants, but also to enhance the biodiversity of the surrounding environment and improve indoor heating, thus saving energy. Vo Trong Nghia explain that the wind flow inside of the house was measured to see the effectiveness of the building design. The wind speed, was measured in eleven spots distributed throughout the building. The data was then compared to the wind speed at the relevant height from outside of the house. The result was remarkable; the average wind speed from the first to the third floors was from 0.15m/s (minimum value at 1F) to 0.53m/s (maximum value at 3F), compared to those from outside from 0.31m/s (value at 1F level) to 1.15m/s (value at 3F level).

With more buildings adopting biowalls across the cityscape, what is next for vertical walls? At present, there are plans to build a Sky Farm in Toronto, Canada. The vertical farm will have 75ha of vertical space for crops and produce the same amount as a 420ha standard farm. The main advantage of the farm is that the proposed structure would only require 1.32ha of land to sit on. As the world population is predicted to increase by 50% by 2050 and the planet becomes ever more tightly-packed, the concept of the Sky Farm appears to be an ideal solution of the ever-growing problem of space.

Whether there will be an increase in greenery across the cityscape is debatable. However, the advances in technology and the increase in popularity on a domestic and commercial level appears that the sky is the limit for vertical gardens.

Categories: Environment, Energy and water