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interview ISSN 2175-6708


Os professores Gabriela Celani e Rafael Urano entrevistam os alemães Tobias Walisser e Oliver Tessmann para o portal Vitruvius.

Professors Gabriela Celani and Rafael Urano interview Tobias Walisser and Oliver Tessmann for the Vitruvius portal.

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CELANI, Gabriela; URANO, Rafael . Chat with Tobias Walisser and Oliver Tessmann. Entrevista, São Paulo, year 18, n. 069.01, Vitruvius, feb. 2017 <>.

Ponte Erasmus, Roterdã, arquiteto Ben Van Berkel, do UN Studio
Foto Abilio Guerra

Gabriela Celani: Can you guys tell us a bit about your work in Germany?

Oliver Tessmann: I'm currently heading the Digital Design Unit – the DDU – at the Technical University at Darmstadt. The DDU belongs to the Faculty of Architecture. We are interested in – as the name says – in the digital and how the digital has an impact on architecture – on the way we design architecture, on the way architecture is materialized. We think that it has a huge impact from the moment you use the computer not as a better drawing tool – you don't replace the pencil with the computer and do computer-aided design – but we are more interested in computational design, meaning the use of the calculation power of the computer in the design process and not in the representation of the design. That means that, for us, the drawing – or better the three dimensional model of the design – is not only geometry, is not only representation of a form and a shape, but it's informed with more aspects – aspects that you cannot show as geometry: load-bearing behavior, deformation under stresses, material properties, environmental aspects, change over time... But also embedding constrains that come out of the later fabrication processes. If all these aspects inform the design model, than we think we can design architecture in a different way.

The Process is not linear any more in the sense of... you as an architect have a brilliant idea that you pass to the engineers to solve the technical problems and make it buildable... but we think that integrating these aspects into digital models helps us improve our designs and the way it is materialized through digital fabrication.  Leon Batista Alberti invented the profession of the architect in the Renaissance time, by saying architects don't build houses, they draw them, they invent them, but they don't build them. He thought architects should only do the drawings, pass them over to the people on site, and not even go on site, because the drawings carry all informations to materialize the architectural idea. And now, five hundred years later, we have digital tools that in the early 1990s we thought they would dematerialize architecture, but the opposite actually happened. The digital and the physical are growing together, through digital fabrication, through the fact that we can use our design models and very quickly translate them into tool paths for robots, for computer numerically-controlled machines. Alberti's separation between the designing and the materializing starts to become blurry. And that's what we are interested in – to bring the thinking and the making together again. To leave very linear design processes and look at feedback loops. Fabrication constrains that would usually emerge very late in the process can now be simulated in the early design phases. They might even become early design drivers instead of late problems.

And I think we are at the very beginning of exploring the possibilities and with every new technological invention we have more possibilities and our job as architects is to think about how can we use them design wise – not engineering wise. As a tool to explore new possibilities. And that's the concept that we have at the DDU. To prove these things or to test these things we prototype, we do small projects, we look at the whole process chain from ideation to materialization, and then, in this chain, we kind of zoom into certain aspects and ask: can we use industrial robots to assist us in assembly processes? Can we crowd-source architectural design, by integrating aspects of architectural design into computer games like Minecraft? So, we looks at the whole process chain from the design to production, and look for opportunities to integrate the digital.

And the other aspect which I think is important is that being here in Sao Paulo you feel the enthusiasm for a new material, the reinforced concrete, and the opportunities that you have. Today, especially in Europe, people are so afraid of technological inventions that they don't see the opportunities; they rather see the threats that come with new technologies, like artificial intelligence and robotics. We would like to have a more positive view into the future as you could find it in the architecture of  Archigram and Coop Himmelblau in the 1960’s

Tobias Walisser: Oliver has brought up a lot of aspects which I totally agree with. My chair in Stuttgart is called ‘Innovative Spaces and Building Construction’. Building constriction is something that a lot of people are working on at this moment, i.e. how to use digital tools, the digital chain , new fabrication technology and so on... I would like to think about the meaning of innovative spaces. And I think that one of the things that people usually forget about is that we do have new tools to design with and we do have new tools to build, but we also can use these tools in a more imaginative way, to envision new things. And it is actually quite strange that a lot of architects use the new technologies but produce the same old stuff. If we consider our contemporary society –  we live in a digital age, we all use smart phones, we are used to have everything two clicks away... all the information we need. Our life is different, we have a short attention span, we expect that things are happening immediately, we try to do things simultaneously, we have different expectations, and I think that leads to different expectations about spaces. This means that as architects we also have to think about what are we going to build. Is it reasonable to say 45 square meters of apartment per person – that's the German average for living spaces – is something we accept and we just design this in a nice way, and now we have the tools to build it in a free form and we can have all sorts of digitized gadgets at home that make life even easier. Like the refrigerator that orders milk when there is no milk. Probably this is not really the question, we must start to ask proper questions, like: can we use these tools to design, to envision, to simulate, to build something that expresses our contemporary needs? We could actually design a house that feels much more spacious, that is much more comfortable at 20 square meters a person, and that is even more sustainable at the same time. And it achieves this reduction without creating the feeling of a loss, but as something we don't realize because it still fulfills our needs, our dreams, and it makes us comfortable, so I think what we should start to use is... we have these fantastic tools to simulate, to visualize things.

So let’s ask the question ‘what if?’. We as architects have the possibility to say what if it looks like this or what if it operates like that... to show people potential futures. And then- once we feel more comfortable that that is the right question to ask and that is the right answer, then we can use the technology that is at hand in a way to make that possible and to realize all of that. So, I would really think that we are at an age in which there is fantastic research being done on a lot of things in the digital chain, and now the most important thing is to take a step back and to say: how can we apply all of this in a way to make it meaningful to society. Not just to use it because it is possible, but to use it because it makes sense, and it makes the life of everyone better. That is something which machines will not be able to substitute. The machine can be a faster designer and a better carpenter and whatever, but the machine doesn't know why to do it and why humans would prefer this or that. That's a truly emotional thing and that's what I like about architecture. Being somewhere between the fine arts and technology. We have to bridge that gap. We have to do both things simultaneously. So we have to explore what is technologically possible, with a positive attitude – absolutely – but we also have to be critical and ask the question: does it make sense and why are we using this? We live in a very exciting time because of a lot of technological advances. We have a lot of problems in front of us that we need to deal with – there's climate change – but there is artificial intelligence???, autonomous driving and so on, and they are great opportunities for us to use them to redefine certain things that all of us have become so used to  that we willnever  question it. For instance, the idea that you cannot walk out and step on the street without running the risk that a car will hit you. Autonomous driving is not so much about the car, it's all about sensors and machines being able to sensor movement and to also detect pedestrians out in the street. That makes it much more possible that humans and robots – the self-driving car is a robot on wheels basically – to coexist in the same space. And that makes it possible for us to redefine the rules of the game; what is a street and what is a sidewalk and what do we actually want to have in front of our buildings. It is really up to us architects, one of the last generalist professions, to ask these broader questions and to look at all of that in a broader context; to take technological possibilities and to make connections between them, especially about our lifestyles and about how we want to live.

Rafael Urano: As all these technologies appear they have in the background climate changes and the perspective that our work will decline in perhaps a hundred years. How does your work relate to this?

TW: Of course we have climate change on the horizon; we can experience it partially ourselves. All of us have a responsibility to deal with it, especially if you have the knowledge to deal with it. But for architects you can say there's a problem but you can also say there's a challenge. I think it's not the question any more if something is sustainable, or green, or not. It's just a must. And there is no problem. We are way beyond the age when it was just about beauty. There's an older generation of architects who had discussions about if something was good or bad, but they basically questioned if you used the right material or if you had designed the ‘right’ form. Today, this it's not the question any more. It's much more how can we do the right things using the latest technology rather than doing the wrong things a little better. That's actually the most important question. Now many people have accepted that certain things need to be changed, and they are applying whatever is possible in terms of technology to make things less bad, which is the first step.

So, for instance, if we make big buildings and we insulate them a bit better, we use less energy. But then we still have buildings which are probably too big for whatever the inhabitants need. If we really want to save energy we probably have to build smaller buildings or maybe make buildings smaller by making them more adaptive and more adjustable. If the geometry of certain spaces can change to make them more suitable for different uses, maybe the space can be smaller... That is how we should take up the challenges... we start to ask the questions and we redefine the questions and we ask what if and we define possible futures and we engage into a dialog about what we really want to have. And in in parallel we develop the tools of how to deal with it. But it must start with an understanding and maybe an attitude or method and it all come to a cyclic process. We are not interested in a linear process anymore, coming from A to B. I.e. in the last century the question was how can I get the most possible cars down the road, and today the question is how we can achieve the best mobility for the most of the people, and then we define what types of technologies we need for this mobility, whether it's walking or it's cycling or it there's cars or public transportation, but the point is we want to allow people a lifestyle to be mobile, independently from whatever technology it takes. It is our challenge to start with the use of energy and resources in building structures. Usually the energy we need to build a structure is less than the energy we need to run it for the next 10 or 20 years.

OT: People will not follow you if you ask them to consume less energy or live in a smaller building... I don't believe that this might work. But what happens right now in Germany is that we started with the passive house – that's the one with the big envelope; you seal yourself off from the outside with thick layers of insulation – and now in Frankfurt we have the first active house, which is a huge building, an apartment building, not just a single family house, but a building with 80 apartments in a dense urban area, which produces more energy than it consumes (4). It was envisioned by Manfred Hegger, who is a pioneer in sustainable architecture in Germany, and what I think is interesting is that it needs more than an architectural vision to do that. You have to engage with politics, you have to persuade cities to build in a new way, you have to think of mobility and the storage of energy etc. you have to think in systems to solve new challenges.

Computation allows us to represent rather complicated and complex systems in which a lot of elements are linked with each other and if you change something at one point the whole system might change. If we use computational power to work on those systems and see architects as part of a larger system, and see the simulation of environmental factors as one aspect in the design process, then maybe digital design can contribute to make architecture more sustainable.

Load bearing elements are often sized according to the one element that gets the highest load while all others might be oversized. If we are able to simulate force flows in a building much more precisely and if we have digital fabrication, which allows us to create differentiation in the production, then we might be able to build more materially-efficient – we allocate material where we need it for load transfer.

TW: Oliver summed up all the elements which are out there and which are technologies or tools which we should use. I'm not sure if I'm looking for disruptive systems, but there's a bottom up strategy of optimization. That's basically what Oliver just explained – how to optimize the material allocation in a building and so on. But we also need a top-down strategy, which is an idea or a vision. And that's what is fascinating about Oscar Niemeyer, there is also a top-down strategy, the vision of a more humane society. And that actually enabled him to go all the length to explore the technical possibilities of a new material, which provided him with the tools to express his beliefs. I think for architects it would be amazing to combine both: on one hand we develop the technology, and the means, and the methods to optimize the technical elements and everything we need to fulfill our dreams, but on the other hand we really have to define what we want to achieve. A lot of technological developments at the moment are driven by optimization, which is a very materialistic way of doing it. Maybe your car can run a bit faster or a bit longer with the same amount of energy. I'm not saying that this is the wrong way of doing it. But what if your car would not produce any kind of exhaust or pollution? Then this car could drive right through this shopping mall and if it also was full of sensors it would know what pace is possible not to run over people and not to crash into something else. And suddenly there's a completely new idea about spaces in which cars are allowed and which ones are just for pedestrians. What is a building and what is a street?  We could redefine the rules of the game. And that's something in which I'm very interested... and I'm curious to think what can we achieve with this. If cars don't run into each other and don't run over people, then you could program the streets. Today there could be a festival on the elevated highway in Sao Paulo. That's something that could be done in a very local way on the GPS. No car can enter the street and people could have a soccer tournament or a birthday party. We would have to define rules about what is more important and what happens when, but the aspect of time would become something totally different in the use of streets, of buildings and so on. Oliver was talking about the structure of the building, which we call the static laws. But actually it's much more interesting to think about laws as something dynamic. The moment you put wind forces o to a building, especially a high-rise building, the dynamic laws are much more importance than the static laws of just bringing the forces down. In a similar way architecture could become more dynamic and probably we could do the same thing with shading, energy efficiency, like walls that can adapt to how much energy they can let through. Why do we make buildings which are hermetic while we wear jackets which are exactly the opposite, which can adjust according to the body heat and the outside temperature? I think we really need to look at architecture as a dynamic system in many different ways, and that is the biggest promise which I see in all the digital  advancements. We could define environments which can interact with the environment and people can interact worth mobility systems and so on. as the next step to make the future more resource-efficient without reducing the quality of life or maybe even offering the comfort that we have today to a broader range of people.  

RU: When I was reading the interview you already gave to Gabi (5) I wanted to ask, in your work, where does it start from? When you go for such a free range of forms how does it relate to the architectural program, how does it relate to the needs from the briefing?

GC: And this question is coming from two architects who attended a very modernist school...

TW: Oliver talked about Alberti starting the differentiation between somebody who designs architecture and someone else who executes it and also the differentiation between a structural skeleton and the outer envelope of the building. There is digital technology and there is a way of thinking digitally, and to me it's always the hybridization. Something doesn't have to be black or white; something can be black and white at the same time. Or any shade of grey, and one is not better than the other. We don't have any preconceived idea of what is good or bad, but you are curious in taking the ingredients and seeing what you can do worth them. The process is very important in our work. I'm influenced by Ben Van Berkel from UN Studio where I worked for ten years and where there were three steps in the design process: imagination, techniques and effects. But basically today I would say: you have to put it in a circle; so imagine all three of them is a cyclic process ad if you run through this process at least once you will achieve an interesting project. We can start with the imagination, which means with an idea. Then create tools to make this idea possible and consequently evaluate it in terms of the effect it should generate... is it leading to the result expected? We could also define a result which we want to achieve. That means to have an idea of how to develop a tool and so on. We could start at any one of these points. We can start bottom-up, say, with a new way of manufacturing something, and then you see what kind of effects that can give you and from that derive an idea or vision. To me it does not really matter. Some projects we start with a program. Some projects we start with the context. Some projects we start with a digital manufacturing method we came across. As long as you combine all steps into a full cycle... it's about the method. It's about the way in which you work, which will allow you to make sure it's not a completely random approach. So the consistency is in the process and not so much in the formal appearance of the project.


HHS PLANER + ARCHITEKTEN. Die Zukunft des Wohnens? Aktiv-Stadthaus in Frankfurt. Detail Magazine, Deutschland <>.

CELANI, Gabriela. Lava, visionary architecture in Berlin. Entrevista, São Paulo, year 16, n. 064.02, Vitruvius, oct. 2015 <>.


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