FOCUS online Earth: Mr. Mann, after Singapore, Paris and Copenhagen, Germany seems to be catching up: Green facades in the cities are becoming more and more noticeable.
Dr. Gunter Mann: And that’s not just beautiful, it’s essential for survival.
Because life comes back through green facades and green roofs? Berlin is not only considered one of the greenest cities in Europe, it is also said to be one of the most bird-rich in the whole country.
Mann: Species diversity is one thing. Another key argument for greening is that cities don’t overheat as much. The statistics show: the hotter the summer, the more deaths from cardiovascular diseases and the like.
This confirms the cliché of city life that might be cool and hip, but it’s not healthy.
Mann: But that doesn’t have to be the case, and I think we should think in two directions at this point. The Bullerby idyll that many have in mind when they imagine life in the country is just as one-sided as the image of the grey, dreary city. In some rural areas of Germany with intensive grain, maize or sugar beet cultivation, biodiversity is now drastically declining. It’s quite possible that the nearby city performs well in comparison.
In the city administrations, the knowledge that nothing works today without green roofs and facades seems to have arrived. In addition to the fear of overheating, the threat of flooding is a major issue. The water that comes down from the sky has to go somewhere. But it is simply not possible to create another park, there is not enough space for the additional avenue of trees…
To what extent do green roofs help against flooding?
Mann: As a rainwater storage tank. With a green roof, at least half of the annual precipitation stays up. This relieves the drains. At the latest since the disaster in the Ahr valley, we have also been alarmed in Germany: it is dangerous if the water cannot seep away. But this knowledge is not new. I’ve been in the industry for 30 years and the case for green roofs and green facades hasn’t fundamentally changed in that time. And even 30 years ago they were by no means new. As early as the Middle Ages, people knew: What you take from nature, you have to give back to nature.
What exactly did you do back then?
Mann: Packets of grass, so-called turf packed on the roof, for example. In Norway you still see that often today. The enemy attacks, maybe even with fire arrows? Where the building is protected in this way, it does not burn as easily. As you can see, it is much more than “just” beautiful when buildings are green.
On the other hand, I believe that the path to the measures mentioned, which are really urgently needed, works via beauty or a better quality of life. Let’s take one of the flagship projects of recent years: the Kö-Bogen 2 in Düsseldorf, the largest green façade in Europe. 30,000 young hornbeams thrive in an office complex. I imagine walking up to this building in the morning and realizing that this is where I work. That’s great. My attitude towards life will be different.
Why exactly what do you think?
Mann: I have nature in mind, day after day. I see how this changes over the months, how the leaves slowly turn brown in autumn, I get a sense of the seasons again – something that many city people have lost. I think this brings us to another important point. Green cities bring us into the now. We don’t have to go out of town to relax, to feel good. To put it exaggeratedly: we consume less recreation, it becomes more natural, we experience it as integrated into everyday life.
However, “going out” has been a big trend in recent years. Many people have discovered forest bathing for themselves.
Mann: On the one hand understandable, on the other hand I wonder if the longing can’t be satisfied in other ways. When I start to describe what I’ve seen on German roofs in recent years, I get excited. There are real landscapes there. Flowering meadows, small groves. When I show photos of it during lectures, it is not obvious that these were taken on roofs.
Green roofs have huge potential for me. The sports field, the dog park, the small pond where I can sit – all of that is conceivable on roofs. I am convinced that it is possible that the majority of people in Germany live in such a way that they only have to walk a few meters to be in the countryside.
But it’s a long way to go, isn’t it? You just mentioned Singapore. City planners have the goal that in a decade or two you will no longer be able to tell from an airplane that you have a city below you. There are already 20-storey buildings that are ground up to the top.
Mann: You hear and read a lot about it, a double-edged sword for me. The fact is: in the past, the media liked to pounce on individual flagship projects. But what is happening in Paris does not apply to the whole of France. And as far as Signapore is concerned: the reporting made me so curious that I made a stopover there on a recent trip. It’s true, the individual projects are remarkable. Hotels, towers, car parks. But Germany doesn’t need to hide behind it. On the contrary. I maintain that when it comes to green roofs, we are world champions.
Mann: We at the Federal Green Building Association determine the proportion of green flat roofs annually via the roofers’ association. Most recently there were 90 million square meters of flat roofs nationwide, almost nine million of which were green. So ten percent. I can’t think of any country in the world that can keep up. One problem is that you only see this part of the green city at second glance. From below, you often can’t even guess what’s going on a few floors up. I can only recommend everyone to take a look at something like this! It is tremendously inspiring and motivating to experience that. I think that looking at what is possible and what has already been achieved is more important than ever these days.
Because we also need good news in view of the worsening climate crisis?
Mann: I see it that way, yes. When I say in a lecture that 44 percent of cities in Germany with more than 50,000 inhabitants are already promoting green roofs, that does something to the people who are listening to me. Something like that makes you want to keep going.
Or get into the topic at all? What can the individual do?
Mann: New buildings are of course predestined for appropriate measures. But there are also numerous possibilities in the area of existing properties. Climbing aids can be incorporated into the masonry, and walls can be planted later. For the facade, the spectrum ranges from ground-based facade greening using so-called self-climbing devices to greening with climbing aids to so-called living walls, which exist completely detached from the ground. When it comes to the roof, the carport or garage is often ideal for greening. In general, pitched and pitched roofs with a roof pitch of up to 45 degrees can also be greened. Admittedly, this is a challenge, but it can be done.
With professional help, right?
Mann: That’s right, contact persons are the garden. and landscaping for greening and roofing specialist companies for root-resistant roof waterproofing.
What grants can you expect?
Mann: That is different. In Berlin, for example, there is a subsidy of 55 euros per square meter for a subsequent green roof in the existing building. However, the area must be at least 100 square meters. The city of Freiburg im Breisgau subsidizes roof areas of 18 square meters and more with 25 euros per square meter and more. Each city decides for itself. Important: The funding opportunities should be clarified before concrete planning.
And if your own city is not included?
Mann: Then you can contact us directly. We’re happy to help with clarification. In general, it can be said that the administrations are opening up more and more to the topic. Even today, almost no construction projects are approved in the cities without greening.
Where will we be in ten years?
Mann: Of course I can’t look into the crystal ball. But if things go well, every tenth house in a German city will have greenery by then, new buildings anyway. People might still go to the local recreation area at the weekend, for hiking, for example. But only to stretch your feet or lie down in a blooming meadow in summer? This will be necessary less and less.