Carlo Baumschlager is one of the most famous architects in Austria. Amongst other things, he became known as a representative of the "Neue Vorarlberger Schule", an innovative architectural movement in Austria at the end of the 20th century. Today, together with Jesco Hutter, he manages the Baumschlager Hutter Partners architectural practice and is a lecturing professor for architecture and urban development at the Academy of Fine Arts in Munich, Germany. Vision, connection, architecture spoke to Carlo Baumschlager about windows in architecture, their tasks, their design, and their limitations and possibilities.
Vision, connection, architecture: According to the saying, "windows are the eyes of a house". Do you agree?
Carlo Baumschlager: A window has to fulfil many different tasks. On one hand, it creates the visual connections. On the other hand, the window has to bring light into the room and thus create atmosphere. And of course, a window has to respond to the physical circumstances. Those are the three levels that have to be considered for a window.
The importance of the window in architecture? Primarily it's about the link between the inside and the outside.
VCA: As someone who designs architecture, what does the window mean to you? How do you treat the window as a design element?
C. B.: Firstly, it's about the link between the inside and outside. I ask myself how much of the outside I want to bring inside — impressions, images, and of course, light. The second question that has to be answered is the arrangement of the window with reference to the room and its functions. Both come together when I think about how I can create an atmosphere with the impressions and brightness that come in from outside. Those are the three key points when using windows in design. To break it down into just a formal decision would not be sufficient.
VCA: The desire to create a particularly strong connection between the outside and inside and to allow in as much light as possible has, in detached houses in particular, led to large-sized windows and even to fully glazed areas. Don't we need more protection again, more intimacy?
C. B.: I think that when discussing the size of the windows, the question of intimacy is not as important as you might think. Of course the link to the outside must make sense. Modern windows then allow you to experience the qualities of an outside space at any time of the day or any time of the year. The trend for increasingly large windows goes with the physical qualities that we have available. Modern windows are now very airtight and offer good sun and noise protection. Another important aspect with regard to the size of the window is the distance present. Using the example of the detached house, there is usually a distance between the house and the neighbouring construction. If this is smaller, however, such as in the city, if the neighbouring construction comes very close or if there is a lot of noise, the size of the window naturally takes on a different importance.
Modern windows allow you to experience the qualities of an outside space at any time of day or any time of the year.
VCA: We often see perforated façades in an urban environment. This line up of windows on a large façade area often creates a rhythm. How attractive is that for you, or rather, to what extent is that a further option for dealing with the issue of windows?
C. B.: Naturally the ratio of the hole to the wall must have a compositional substance. Anyone whose business is architecture and who wants to deliver good work has to consider this question. In urban buildings however, the prevailing physical circumstances are also very important. For example, the window has to deal with noise emissions. This is part of the decision for the size of the opening. Here, the boundary between creative desire and physical conditions must be found.
VCA: Even today, despite the progress in sound protection, heat protection, etc.?
C. B.: Yes, of course, even today. That is evident from the discussions about the fully glazed façade that we have also constructed ourselves, based on the knowledge of what the material can do and what the resulting economic and ecological significance is. This has created a high level of complexity. In office construction, therefore, the insertion of a window is precisely defined. We know that in the ideal situation, the glass content in the façade should be no more than 50%. If it exceeds this, the physical problems have to be dealt with economically.
VCA: You often resolve such problems by applying a second skin that you place in front of the façade, thus creating an additional design level.
C. B.: Yes. If the architectural and spatial concept requires that the window aperture extends beyond the limit determined by physics, you have to think about what additional layers to introduce to solve the physical problem. Double-skin façades offer sound protection and the possibility of shade so that the light and heat input resulting from large openings does not become too high.
VCA: In your opinion, can this design level be used to create an individual element, for example control of the sun protection by the user? Is there an appropriation here, with something from inside finding its way outside?
C. B.: That depends on the type of building. For a detached house — regardless of whether it's a new build or a renovation — in my opinion it is correct to take account of the user's individual ideas. The sun protection then affects the window geometry, the technology that is used, and the form that a house takes when the user changes the shading to meet individual requirements. The situation is of course different for office buildings. Here, the sun protection is controlled centrally — with all of the known problems that brings. The underlying control concept is based above all on energy aspects and does not allow much in the way of individual design of light and view.
VCA: Speaking of renovations: Replacing windows is a classic renovation situation. On one hand, the windows and the building form one characteristic design unit. On the other hand, the design of the windows and often even the window apertures no longer meet modern demands. Do you favour retaining or reconstructing windows or replacing them to meet modern demands?
C. B.: There is no one answer to that question. You have to act correctly according to the task, the function and the change in conditions. In principle, the renovation of windows is largely connected with the question of energy gain/loss. However, for important or historically interesting buildings, the issue is to retain the impression and the proportions between the wall and the opening — unless the functions change. In that case the window naturally plays a different role to that in the original situation.
VCA: Thank you for the interview.