Urbanization is continuing apace. Researchers predict that just 30 years from now, two thirds of the world’s population will live in towns and cities. Levels of urbanization are also increasing in Switzerland, with far-reaching and frankly dramatic effects on our ecosystem. So how can we lessen the impact? Vertical greening provides the key.
Summer 2020 saw plenty of days when city-dwellers found themselves envying those in the country. It was hot. Very hot. The thing is, in summer, cities become islands of heat; on an average summer’s day, the local city climate is up to 7°C hotter than the surrounding area. Why is that? Because the buildings and their closed-off surfaces act as powerful heat storage systems, and built structures also act as a barrier to the flow of air. At the same time, cities lack green spaces, which naturally cool the environment. And then there’s all that waste heat from industry, air conditioning units and vehicles. It’s clear that urbanization and climate change are only exacerbating this issue. Quality of life is continuing to fall in our cities as ever more people flock to live there. It’s not only the human population that bears the brunt of these changes, either: local biodiversity is also on the wane due to the heat, whilst dry earth leads to flooding.
Green façades provide one means of counteracting these heat islands effectively. It’s all about going vertical instead of horizontal, allowing for large expanses of greenery even in the most densely built-up city centers. By cooling the building and its immediate surroundings through evaporation and shading, they play an active part in compensating for the climate deficits that exist in cities. “In theory, green façades would allow entire streets to be cooled down,” says Magus Wessel of the environmental organization BUND.
In densely build-up city centers, green façades are a clever way of allowing large-scale planting despite a lack of space.
And that’s not all, by any means. Quite apart from their cooling effect, green façades also offer a number of advantages for those who use the buildings, the city as a whole, and the environment at large. Above all, greening improves the microclimate. Plants absorb carbon dioxide and produce oxygen. They increase air humidity and absorb fine particulates via their leaf surfaces, making the city air cleaner and healthier. Green façades also promote biodiversity by providing a habitat for insects and birds. Their foliage absorbs sound waves, so they also offer effective noise protection. Last but not least, they take the pressure off storm drains in the event of heavy downpours.
An enchanting green space: a roof terrace in the heart of Lucerne, with a view of Mount Pilatus.
A place to meet and linger within the city, surrounded by lush greenery.
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The costs of maintaining a green façade shouldn’t be overlooked. However, they can be kept to a minimum by using highly robust, low-maintenance plants. “As a general rule of thumb, maintenance costs amount to about 10% of the total cost of a green façade,” says Michael Hagenauer, Sales Consultant at Hydroplant. When putting together a cost-benefit analysis, it’s also worth bearing in mind that there are also considerable savings to be had by installing a green façade. The greenery acts as natural sun protection and insulation for the building, thus lowering its power consumption quite significantly. On top of that, plants provide protection against damage caused by external factors – graffiti and bad weather are just a couple of examples – and help to maintain the building’s structural condition over the long term. Having a green façade also means that you can dispense with expensive façade materials that might otherwise be required for visual appeal.
On this housing estate, climbing plants grow up a steel cable structure and transform the balconies into mini green oases.
Knowing what we do about green façades, it’s hardly surprising that ever more “green buildings” are springing up around the world. Famous examples include the Bosco Verticale in Milan and the ACROS Hall in the Japanese city of Fukuoka. Closer to home, the Swiss have long recognized the benefits of vertical greening outdoors. Hydroplant is playing a pioneering role in this sector and has already brought numerous projects to fruition. We don’t think of greenery as a purely aesthetic “extra” but rather as an integral component of modern architecture.
The Bosco Verticale in Milan is regarded worldwide as a prototype for the cities of tomorrow.
The latest example is the Greenwall of the Circle at Zurich Airport, which is currently one of the largest vertical greening projects in Switzerland. We developed the detailed concept for the evergreen, almost 150 m-long wall in conjunction with Zurich Airport and Ramseier & Associates Ltd. To create a coherent look, we opted for robust mixed planting in complementary tones, made up of plants ideally suited to the climate at the site. “There’s no doubt that the sheer size of the wall presents a challenge given the exposed location. But that’s what makes the project truly special,” says Michael Hagenauer, who is leading Hydroplant’s contribution to the project. The mounting construction and irrigation technology are also quite extraordinary. “We developed a special structure especially for the Greenwall, so that it could be installed at a distance of 80 cm from the concrete wall. This keeps the underlying structure accessible for inspection whenever necessary.” The first stage of the visionary project is complete, with the second stage set to run until late spring 2021. At that point, the 600 m2 Greenwall at Zurich Airport will be unveiled in all its glory, ready to enhance the experience of people, flora and fauna alike.
A complex structure with a unique impact: the Greenwall at Zurich Airport.