How do skyscrapers affect the weather?

Architecture and urban conceptsNew skyscrapers in the cityscape

"The view from high-rise buildings is as wonderful as from a high mountain. That is perfectly clear. But you also have to see high-rise buildings from below: How do they affect the urban fabric?"

"What is a skyline? Is a skyline what Frankfurt has and what Manhattan triggers in our heads? Or is a skyline a different way of looking at the horizon? If the skyline is a different way of looking at the horizon, then we need that. Then we have to deal very intensively with it, where do we want prominent points and where do we not want them? "

Building sin with a good prospect

"From now on I'm recording." "I'm with my neighbor right now, so I look out in the other direction, but I can also look from the balcony." "Yes." "My name is Götz Diekmann. I live in the Uni-Center on the 25th floor, now for 12 years, and I am chairman of the owners' advisory board."

Götz Diekmann is an engineer by profession and is a passionate owner of a small apartment in the university district of Cologne. With almost 1000 residents, the Uni-Center is one of the largest in Europe. Diekmann knows the building from the inside; many call him the caretaker for the weekend.

"It's evening now, so it's dark while we talk on the phone. We are not allowed to meet, otherwise I would have liked to visit you because of the corona pandemic. When you look out the window, what do you see of Cologne?"

"At the moment I'm looking closely in the direction of the Eifel. From Cologne itself I can see the southwestern part. I can see as far as Bonn and almost as far as Aachen. I haven't seen that many illuminated apartments for a long time. And I live on the 25th floor."

The Cologne University Center is one of the largest high-rise residential buildings in Europe (imago stock & people / C.Hardt)

"Is that high for mere mortals who don't know about high-rise buildings?" "Yes, I measured it once, it is so 75 meters above the ground. But that is by no means the end of the Uni-Center. In the core building, the top apartment is on the 43rd floor, so another whole corner higher . " "Does the building sway?" "When it's very stormy, it wobbles a bit, yes. That means it fluctuates very easily. That was of course very new to me, because we have always lived with the family in the country, in the countryside, close to the forest, and at most on the 2nd floor. Every time you come into this apartment, you are simply flashed by this view. "

Urban planners longing for a skyline

I have already found the World Trade Center in New York and the London Shard with its 309 meters attractive; But from the outside, the Uni-Center in Cologne is a building sin, typical of the 1970s, when the population wasn't even asked. That was still the case in the early 2000s, as I found out by chance during a panel discussion in Munich's Maximilianeum. Architects and town planners, environmental activists and monument conservationists discussed the Munich skyline. This skyline doesn't exist, but some city councilors want one. Large architectural firms are scratching their feet, and investors are setting up their lobby in the town hall. In Munich, so the tenor of the panel discussion, one would like to create a skyline out of an inferiority complex that does not alleviate the housing shortage in the least. Maximizing profit with small areas of land by stacking floor on floor is of course an investment dream.

Initiative against high-rise growth

I learned a lot at this event, for example that years ago the editorial offices of the Süddeutsche Zeitung moved from the old parent company in downtown Munich to a high-rise building on the outskirts and want to move away quickly, into a much flatter, wider building. Why? Because in a tower there are no more casual conversations, as they were quite common in long corridors. And I learned that a new wave of skyscrapers is rolling towards us. Architects call them high-rise buildings.

The Munich architect and urban planner Udo Bünnagel, member of the "Münchner Forum", an interdisciplinary association of experts who has been fighting against the proliferation of high-rise buildings in Munich for 15 years, was also on the podium. I make an appointment with him in a rather unpopular office complex made up of two towers, the "Highlight Towers" in the north of the city; exactly where the A9 motorway ends.

The "Highlight Towers" in Munich (imago stock & people)

"We are now going up the stairs from the 23rd to the 26th floor, and then we're almost up there. Great view." "We're going from the 26th to the 29th floor." "Ah, of course you don't notice that here. Is there anything else about us now?" "Just technology." "Just technology, okay. Well, when you're in the skyscrapers, it always looks great." "The view from high-rise buildings is naturally as wonderful as from a high mountain. That is perfectly clear. But you also have to see high-rise buildings from below: How do they affect the urban fabric?"

Disturbed lines of sight

A clear day. Alpine view. We are 20 meters higher than the towers of the Frauenkirche on Marienplatz. A street runs straight from our building to the city center: Leopoldstrasse, which is called Ludwigstrasse towards the Feldherrnhalle. Udo Bünnagel:

"This axis is actually the historical axis that Ludwig I had planned. So a historically very valuable situation. And that is massively disrupted by these two high-rise buildings."

During the planning phase in the early 2000s, investors and architects only showed the building from the perspective of the motorway, but not from the city center. Viewed from the motorway, the images looked like a delicate approach to the skyline. What hardly a Munich resident noticed when it was being built was that the building had grown considerably beyond the planned height. Bünnagel:

"The whole thing is due to a legally not entirely impeccable increase in building rights in a development plan procedure that was carried out in accordance with Section 13a of the Building Code; that actually means an insignificant change. But the two high-rise buildings, which were planned to be 99 meters high, are now 123 meters high."

Tricks with the floor height

The trick was one of many with which building plans can be drastically changed without consent: the city had discussed a height of 99 meters with the client, but not the height, only the number of floors in writing: 30. The building plan had a ceiling height of 3.50 meters incorporated, as is common in normal low buildings. With point high-rise buildings you need more, if only because of the air conditioning and sprinkler technology. Every architect knows that. The Highlight Towers were completed in 2004. 25 meters too high.

At the same time, a giant, the Uptown high-rise, was built in the middle of the rural Munich district of Moosach, even without the participation of the population. This building was supposed to be 200 meters high. The aversion to the tower increased with every new floor that was placed on top of it. Citizens' groups achieved an early construction stop - 50 meters earlier than planned. These two building sins, Highlight Towers and Uptown high-rise, have meant that nothing has been built in Munich over the 99 meters of the Frauenkirche since then. And other cities learned from it that building on heights is no longer possible without the consent of the citizens who live in the neighborhood.

Illuminated apartments at Cologne University Center. (imago / Future Image)

"Can you just open the window, Herr Diekmann?" "Yes." "Can you hear the wind?" "At the moment you don't hear the wind that much." "A little bit." "When it's really stormy, you can hear a grumble, whenever there is a gust, when the wind presses on the entire window front. Then it moves, and it can also crack quietly."

Long-running high-rise discussion

The planning department responsible for the high-rise construction in the Düsseldorf City Hall, Cornelia Anbke:

"The high-rise discussion happens every now and then. It's not new. It took place in Düsseldorf right after the war, during the reconstruction. So you thought about how to get in touch with the world's elite. You tried to find out how with high-rise buildings with the Dreischeibenhaus or the Mannesmann building, then there was the high-rise discussion in connection with the housing shortage of the 1970s, which triggered a very simple stigma in society as to how one sees high-rise buildings.

And they are currently available in a double sense. The point is that you want to go up, because land prices have simply risen, because you simply want to gain space over height. The other part, however, is that one is thinking again about typologies that open up new qualities in the city not only for commercial real estate but also for living. And from international comparisons, we know that high-rise buildings can certainly be attractive. And I believe that there is piece by piece a new view of the skyscrapers. "

The elevator as an obstacle to communication

Numerous studies in recent years deal with social coexistence in the city. High-rise buildings play a subordinate role here. A classic about living in high-rise buildings is a book by urban sociologist Ulfert Herlyn that was published 50 years ago. Herlyn questioned things that skyscraper architects considered god-given, such as elevators. He found out that the elevator interfered with communication on each floor. A quiet conversation between two neighbors becomes impossible with a door that can open at any time. The elevator door as a symbol of acceleration and rushedness: impatient waiting, glances at the floor, and when the elevator finally comes, get in and away. Today elevators are built more transparently, often in their own towers and glazed.

"The elevator is not necessarily something that brings people into communication."

The social anthropologist Eveline Althaus from the ETH Zurich's Wohnforum. She recently published a scientific paper on the "high-rise social space":

"It's like a small microcosm. And that's totally exciting about high-rise buildings, also as a research subject. In Zurich, a 70-meter high-rise building is currently being built in the Koch area by a housing association, where it is deliberately placed on the mezzanine floors, starting with the stairwells want to create open common areas. "

Grown social structures

For her research project, Eveline Althaus spent months studying how people lived together in two Zurich high-rises that are older and where social structures have emerged over the decades that nobody would have expected. The study refutes many common views about the general ghettoization of large residential buildings. And it highlights factors that are necessary for success:

"Nowadays people love living there very, very much. They have nice apartments, they are affordable, they are bright, they have a good living environment. There are many children. Families in particular really appreciate the fact that there are traffic-free outdoor spaces where the children can Being able to play freely, and not always having to be supervised. There are shops and meeting places nearby - that has changed over the years - schools, childcare and access to public transport. These are all qualities that people value .

And what is really striking when you look at this high-rise structure: From the outside there is still a really negative image. A lot of people think it's ugly, say it's just a ghetto, everything is anonymous there. So there are a lot of stigmatizing elements that come into play.

I think that of course has a lot to do with how this place is run, that there are caretakers on site, so to speak, a caretaker who is very important. But there is also neighborhood and community work, a wide variety of leisure activities, i.e. opportunities to meet. These are all elements that make living there very attractive for the residents. "

Idea generator for future living

These buildings provide ideas for future living and have refuted many assessments from the past. An original sound from Rias Berlin on the subject of urban planning and citizens' wishes from 1956:

"Well over 100 submissions dealt with the construction of high-rise buildings. Most of them were against. Senate Councilor Stephan tried to do justice to all parties:" "We agree with you that the high-rise apartment building is by no means suitable for children. One should avoid it To put families with children in the apartment buildings, at least [not] on the upper floors. Although, according to my own observation - I live on the 15th floor of the high-rise building on Roseneck - it is easier to go down in the elevator with the stroller from 15th floor, than struggling down the four flights of stairs. I generally agree with you that families of children should not go to the skyscrapers. "

Eveline Althaus: "In Switzerland it started around the 1950s with the real high-rise building, the building of residential high-rise buildings. Max Frisch came back from New York and was very enthusiastic when he saw what urbanity was emerging in this one Small-scale Switzerland had never been there. He then said that it is actually not that brave, it is more the high-rise buildings that are being built here, that is, very small-scale houses and settlement structures. He was disappointed Places. "

From brick to steel column

Inauguration of the BASF high-rise E100 in Ludwigshafen. A broadcast by the RIAS in 1956:

"Its outer skin is purple, made of Venetian glass mosaic, the aluminum gutter and window frames are silver. And the window panes are reflective. The window panes. From the outside, the windows are actually the main part of this house, which looks like an upright, narrow book. Its upper edge is exactly 101 meters and 63 centimeters above the street. This house has 26 floors above the ground. An American would perhaps smile pityingly. But for us this is a skyscraper. "

The building has long been demolished at great expense.

The pyramids are high-rise residential buildings for the dead. Brick high-rise buildings like the old technical town hall in Munich have very thick walls, small windows and, at over 40 meters, are already reaching their static limits. Then came steel and, in 1848, reinforced concrete. Today, most of the point high-rise buildings are constructed along steel pillars that are stuck deep in the ground. In most cases, concrete walls and steel stiffening systems are added. The rigid concrete needs the steel because of its flexibility and tensile strength. You can recognize these "bracings" made of steel as struts on the outside of many high-rise buildings, they are often hidden in the facade.

The Shanghai Tower (right) in the ensemble with the Jin Mao Tower and the Shanghai World Financial Center (picture alliance / dpa / He Youbao)

Stable even in earthquakes and strong winds

Buffers that absorb vibrations are built into the bracings on the outer walls of modern high-rise buildings. In earthquake-tested Japan, these buffers are made of viscoelastic materials such as silicone. This is not enough for very tall buildings, especially when gusts of wind above and vibrations below lead to unpredictable vibrations. Every house has its own natural frequencies that should be avoided. They can be simulated well with computer programs.

Now there are weights in the roof of modern high-rise buildings that make up 2 percent of the total mass of the building. With a total building weight of 10,000 tons, 200 tons swing around on the top floor. That's about 200 cars.

Vibration damper in the "101 Tower" in Taipei (imago stock & people)

However, the weights turned out to be too static and optimizable for more complex vibration patterns - wind, temperature, soil tectonics. Here, too, Japan is leading: they said goodbye to fixed weights and switched to liquid tanks, which are filled to different levels depending on the vibration.

Thermal power station in deep sleep

The 50-year-old Uni-Center in Cologne also has weights in the upper range, albeit for different reasons. Götz Diekmann, resident and connoisseur of the giant:

"The old cogeneration plant with three huge oil boilers is on the 45th floor. Back then, the architect did not consider that they are simply at the end of their life after 15 years of continuous operation. There is no way to get them out of there. They are in there, in the Sleeping Beauty since the mid-1980s. Since then, the house has been relying on district heating. There are a few things that the architect, I now claim, did not fully think through. "

The effort increases from a height of 60 meters

The fact that the original heating system is not in the basement is mainly due to the energy required to pump up the water. For architects, a construction height of 60 meters is the limit above which the effort increases considerably. Pumping up water for heating and air conditioning and pumping wastewater downwards at a slower pace. And the garbage. How does Götz Diekmann dispose of his?

"We have a garbage disposal system for each floor for the residual waste.Even three times per floor, because every house is basically completely independent, so that there is its own garbage disposal in every house, in every wing. "

"Today it is illegal under building law to have garbage chutes. The conversion costs would be enormous?" "Yes. About a year ago the state parliament decided that garbage chutes generally no longer get a permit in North Rhine-Westphalia, but acknowledged that there are exceptions. Conditions are then fire protection precautions, and it must be ensured that the garbage separation works."

The 828 meter high Burj Khalifa in Dubai is the tallest building in the world (www.imago-images.de)

The tallest building in the world is the Kalif Tower in Dubai: 800 meters. It tapers considerably towards the top, like a needle, which is mainly due to the fact that the wind does not offer a large area of ​​attack. Its facade was designed to be streamlined using the wind tunnel simulations customary in car design, with edges flattened at certain points.

Getting to this height with a single elevator is technically impossible. The ropes that pull and stabilize it would be too heavy. Construction technology has also changed significantly in recent years. Today whole parts of floors are put together on the ground, transported to the crane by truck, pushed into the scaffolding at a great height by crane.

High-rise buildings more expensive in manufacturing costs

"Is a high-rise even something that pays off?" "There are higher requirements for fire protection, building services and structural requirements in high-rise buildings. Therefore, one must expect that the high-rise building will become more expensive in terms of production costs, and thus, especially when it comes to the subject of the residential building, only is conditionally a contribution to inexpensive living. "

Christa Reicher heads the chair for urban planning at RWTH Aachen University. She is involved in the planning of high-rise buildings in several cities in North Rhine-Westphalia and declares war on certain investor desires in Düsseldorf:

"It will be the case that there are also areas that we will definitely declare as taboo zones for high-rise buildings, because there are problematic ecological and wind flow conditions there, or because the view of certain historical buildings is severely impaired there. And elsewhere you will simply have to think a lot about developing high-rise clusters or areas for high-rise buildings there. "

"Internal compression before external development"

Above all, urban planners today have an insight that is not yet old and that promotes the controlled construction of high-rise buildings. Richer:

"Internal densification before external development. After all, we do not want any further urban sprawl on the outskirts of our cities."

Meadows and forests that give way to sleeping towns and shopping centers at the edges. And city centers, which are deserted at night, with their threateningly black office high-rise facades. Progressive urban planners never thought of the high-rise as a single piece, but rather in connection with everything around it. Christa Reicher is also interested in the historical classification. Because one could learn from the Wilhelminian style houses that building at a moderate height of 5 storeys and deep into the inner courtyards brought more living space than a high-rise building with its small footprint, but the large free space around it:

"So you know that the social structure is an incredibly important component for the functionality of high-rise buildings. I was allowed to accompany the demolition of high-rise buildings in the city of Kamp-Lintfort, the so-called white giants. There were three identical high-rise buildings on an inner-city area. And the building that worked well was what had a caretaker, where someone took care that the apartments were in good condition, that the surroundings were carefully looked after.

After Kamp-Lintfort also in Duisburg: the end of the line for an unloved high-rise apartment building (www.imago-images.de)

The two who stood by are completely neglected. There was vacancy. Although the apartments were the same, one worked and the other two didn't because there was no carer and because there was such a downward spiral in terms of social occupancy. This shows that you can't just say that the skyscraper is working or that it is not working. It depends on the social and societal framework. "

"Mr. Diekmann, when you got home, shortly after 6 p.m., did you run into anyone in the house, apart from the one at the gate below?" "Uh, no. I drove into the underground car park and all the way up - no, I didn't meet anyone."

Modern mixture of living and working

"We coined a sentence like this in Düsseldorf: Social Return."

Cornelia Anbke, Head of the Department for Mobility, Planning, Building Supervision, Real Estate Management and Surveying. I met you at the beginning of the Covid 19 crisis in Düsseldorf City Hall. We didn't shake hands. There was still no talk of home office. But the idea is in the social return of the skyscraper:

"Social return includes the inner mix. It can definitely be a modern mixture of living and working. A high-rise, for example, offers the possibility of really demonstrating the city of short distances, and in a very confined space. A high-rise can definitely contain components that are valuable for the environment - from daycare to care facilities - the nursing emergency in cities is a very important issue. This goes hand in hand with resource-saving construction. And I believe a high-rise can also do one thing: it can give back space on the ground floor , but it can also free up open spaces in the high-rise building itself, from above, for a view of the city skyline or for the center of the district or something else. And a high-rise building has become an exciting part of urban densification, the new urbanity they said they were going for the crowd ... "

Offices help finance social housing

... that means living and working close together without open spaces. The social added value can be financed, according to Cornelia Anbke: the high-priced offices help finance the social housing. This makes the modern high-rise the focus for a new way of thinking about life in the city:

"This is city! City is mixed in the original. And that's why I can well imagine that we think of living down to earth in some places. Le Corbusier has already felt the second thing in his buildings, by the way, that he always says: The public space also runs through the building. And inside the building, the inner space and the outer space are networked. And if we think about it, when it becomes clear to us that there isn't a separation between the outer wall of the building and the public space, then we will around the buildings we don't have any neglected residual space, but then we as public administration think along with the investors about public space. And then we come to concepts that are not as fragmented and sectoral as the city of the 1970s, but rather on the integrated, which we live today, life plans are also integrated, which you can then also think about and realize I assume. "

The new, ecological high-rise

Everything else takes a back seat to these considerations. Of course, the new high-rise will largely be self-sufficient in ecological terms, with new building materials, insulation, solar cells and wind turbines. Flushing the toilet from a height of 50 meters will convert its kinetic energy into electrical energy when it falls, just like when braking modern buses. Of course, new skyscrapers should be beautiful, because people have learned that living in a wooden skyscraper like the Hoho in Vienna with a height of 84 meters is more comfortable than in a glass palace. Corneliazuschke:

"If you go to Milan, for example, and look at the Bosco Verticale, you will notice how people live stacked up, calling out something to each other over the balconies. Another very interesting point: at some point we learned that balconies should not be overlooked . Who says that? There are living machines where at first sight you say: How does it work? But suddenly you notice that offset terraces restore the horizontal feeling. I then experience neighborhoods again. I can shout something to someone, I can but also seal me off.


Green skyscrapers "Bosco verticale" in Milan (unsplash / Chris Barbalis)

That is why, whenever high-rise buildings come up for discussion with our committees - and I think that's great - our committees then keep saying: There needs to be zones in the cores of high-rise buildings that can also go over two or three floors, in which, for whatever reason, one feels like staying. Be it because it is an internal greenhouse, be it because you can look out in all directions from there, be it because there is a gym or a bar, no matter what. This machine can, so to speak, be interrupted by functions that have always attracted us humans and then also lure us vertically. "

Two new tall towers for Munich?

"We're going down at a very high speed now." "Yes."

I ride 100 meters down in the elevator with Udo Bünnagel, the critical architect and urban planner in Munich. All city councils are feeling the pressure from private investors, but also from international finance capital, to finally be allowed to build up again. In Düsseldorf and Dresden they are taken seriously, but they are not left to decide. It's different in Munich. In the city center, investors are already scratching their feet: They want to build two tall towers around the listed former parcel distribution center. Deceptively beautifully visualized. Bünnagel:

"Every city, every village has the right to determine where and in what height and in what density may be built. But it has meanwhile become standard in many cities that very potent investors use certain leverage to ensure that their ideas are implemented. And this is now a very big problem. "