Patrick Blanc is a botanist and his company developed the green wall into a high-tech version. In the ‘mur végétal’ the water system is essential. This vertical garden consists of a metal frame with a PVC plate as a foundation for two layers of polyamide felt. This layer acts as a sponge, similar to moss. A network of pipes transports nutrient-rich water to the plants. Gravity ensures that the liquid slowly drips down from the soaked felt. At the bottom of the wall, a gutter collects the excess water and brings it back into the system. The selection of the plants for each project depends on the type of environment, the local microclimate and the amount of daylight. The first vertical garden was implemented in 1986 at the Cité des Sciences et de l’Industrie in Paris. The first project with a large-scale vertical garden was the wall of the Musée du quai Branly in 2006, designed by Jean Nouvel. More than ten years later, vertical gardens can be found all over the world. The system is certainly not an example of spontaneous nature; and because there is no soil, it is an ecosystem that depends on technology. Nevertheless, insects and birds find food and shelter here. These vertical gardens furthermore provide a pleasant, heat-absorbing microclimate, as you can feel around the Oasis of Aboukir in the hot summer months.
Located in the Thames corridor in London, the Deptford Creek area now has several brown roofs. The first and most famous of these is the roof of the Laban Dance Centre by Herzog & de Meuron. Before the redevelopment of the area, the brownfields with a lot of debris and bricks had become the habitat of various rare plants, insects and birds, including the black redstart. When the declined area was redeveloped and new buildings were constructed, the roofs were covered with crushed concrete and loose bricks from the demolished buildings that once stood there. Between this substrate and the waterproofing layer, there is only a 10-milimetre water storage membrane without drainage. The resulting biotope has characteristics similar to those of the original ‘brown’ terrains. The vegetation was not sown, but has gradually taken over the roofs. By now, more than a hundred plant species have colonized the roof and some rare insect species are found there. The black redstart is doing well in its new rooftop habitat.
The 50-metre tall residential building of the M6B2 Tour de la biodiversité project rises from the urban landscape of Paris. The tower was exempted from the Parisian 37-metre building height restriction, on the condition that it would be ‘green’. The designer decided to actively use the tower to improve local biodiversity. Its most important feature is the planting on the roof and on the façade. Seeds for the plants were collected from the forests around Paris. Aided by the wind and the extra height, the seeds can now be distributed throughout the city. The vegetation will constantly change the building’s appearance, and the moiré pattern of the titanium cladding gives it a subtle, fluctuating character. Various (climbing) plants and trees with a different growth rate grow along nets on the façade. The rapidly climbing vines will first overgrow the façade; the slower shrubs will follow later. Eventually, the planted young oak trees will take over. The trees stand in long, narrow cylinders. Research has shown that trees have a higher growth rate and a better health in these than in a conventional container. The entire complex consists of five buildings. Parisians can stroll through the protected gardens that were realized for them at the street level.
The garden of the government office Kempkensberg in Groningen is not only there to enjoy for the approximately 3,000 employees of the Education Executive Agency and Regional Tax Office, but for all the people in the city. Covering an area of 25,000 m2, largely atop an underground car park, it is an exceptionally large roof garden. This garden was created in such a way that it forms a biotope matching the ecology of the adjacent green areas Sterrebos and Helperzoom. Consultancy Arup conducted wind studies to find out what nuisances the new building could cause for people, but also for the birds and bats that live in the area. For that reason, 3-metre high, planted screens were designed. These screens were radially placed from the main building towards the countryside. A vegetation mantle encloses the intensively planted gardens around the building. It consists of a thicket of young oak trees that will eventually replace the existing old trees. This way, the visual integration with the ancient Sterrebos will also be maintained in the long run. Moreover, it strengthens the migratory routes for bats living in the area. Right through the garden, a route was designed for dragonflies and butterflies, species that prefer open, flowery vegetation. In the wake of the many insects, and for the seeds and fruits it provides, the birds have also come to the City Garden. The mantle provides good shelter; the multi-trunk trees in the middle still need to grow a little.
Vegetated roofs can play an important role as oases where plants and animals (especially birds and insects) feel at home. By now, many versions have been developed, each with its own specific merits. In Wageningen, there is an experiment with a green-blue version, focusing on water storage in addition to ecological values. A roof package was placed, providing space for grasses and larger plants with water storage underneath. This in contrast to the many green roofs with a relatively thin substrate layer and sedum vegetation. Sedum is drought-resistant, but when it rains, the water runs off rapidly. So the roof can survive dry periods, but is much less useful when it comes to reducing the growing problems with water due to climate change. Vegetation with many grasses is much better at retaining water. Hence, scientists are experimenting with a so-called polder roof at the roof of the NIOO (Netherlands Institute of Ecology) building, a wet version of the green roof. The field of many kinds of roof packages is part of a research programme on the specific qualities and limitations of each system. One of the aims is to find vegetation that can survive periods of drought and at the same time retain water longer. In addition to the green roof, the building has ecologically rich ponds right next to its entrance. The gardens behind the complex are also used for experiments. There is a large insect wall, for example, to study what choices work best in terms of biodiversity, just like the experiments on the roof.