The so-called Poseidon House on Theodor-Heuss-Allee in Frankfurt/Main was originally built in 1986 and designed by Nägele, Hofmann, Tiedemann & Partner. Now Schneider+Schumacher is set to refurbish and upgrade the architectural ensemble that measures 62 meters in places. The architectural firm recently heightened its public profile with the much-acclaimed underground extension of Frankfurt’s Städel Museum. At present, the building boasts 24,000 square meters of office space, which will be increased to 40,000 in the course of the refurbishment. Most of this extra space will be provided by a new building in the northwest section of the site. With plans foreseeing 17 stories, this new architectural component will easily size up to the taller parts of the existing structural elements. The foyer and outdoor areas will also be extensively refurbished or completely redesigned. All reconstruction and extension works are centered on reducing energy costs, aspiring to receive LEED “Green Building” certification in “Gold”. The approach the Frankfurt-based architectural firm has taken to the building’s façade represents a particularly interesting aspect of this project. Thomas Wagner spoke to Michael Schumacher about the refurbishment and extension of Poseidon House, whereby other projects focusing on responsible “refurbishment and upgrading” and basic considerations of work with facades also came up for discussion. MICHAEL SCHUMACHER “Refurbishment and upgrading” is a subject that has greatly interested us for a good decade now. In Europe we already have lots of buildings with sound basic structures. If we are serious about sustainable construction then such options must be explored thoroughly. We face a similar dilemma when driving a car that is getting on in years. Do I drive it for a few more years with an eight-cylinder engine or do I buy a new six-cylinder that will save no more than three percent in gas? In other words, refurbishment and upgrading is an option worth considering based on the sustainability aspect alone. Legal matters and building regulations also play a role in the decision as to whether it makes sense to keep and redesign an existing building as opposed to building a new one. As regards the Poseidon House plot, the idea to build a new high-rise did in fact come up. But after weighing up the prospects, options, costs, potential uses etc. the idea was thrown out. Time was also a significant factor in this decision. There was a future tenant who wanted to move into the premises as quickly as possible and the entire construction process for a new building would have taken longer than refurbishing and extending the existing building. We therefore decided to significantly increase the surface area of the existing Poseidon House. So we won’t just be replacing the façade; the building will be much bigger once works are complete too. The rear connecting beam was then added to the design first to create more usable space and second to add another connecting point between the two sections of the building. These changes to the bulk of the building as well as the use of cutting-edge energy technologies inevitably resulted in the need for a new façade, whereby this would now need to follow a different principle in terms of design. The old façade offered vertical contours, an attempt to create an optical illusion that the several smaller high-rises were in fact taller. The new façade on the other hand aims to bring the entire ensemble together as one unit. That is the key design principle here. Considered from a technical point of view, today it is always a matter of choosing a façade that wastes as little energy as possible. SCHUMACHER For me, “signature” is generally a difficult term in architecture. Architecture is determined by its location as well as the respective culture. It isn’t about a signature. Take Richard Meier for example. In my opinion, his buildings are much better suited to the Californian climate than the European. A characteristic standard design may be effective in drawing media attention to an architect and a building, but it is difficult to translate to different locations. We have always avoided architecture like this because our buildings should be associated with their locations and not necessarily with our name. Of course, this kind of attitude is ambivalent, because nowadays architects are forced to have an interest in creating an association between their buildings and their names for marketing purposes. Although in principle this is something that arises from the construction project itself. Frankfurt’s Silberturm, the headquarters of Dresdner Bank, provides a very good demonstration of what this actually means. In this case we were the ones to say: Let’s just keep the silver façade. The Silberturm is not just any old building; it’s a special building, a 1970s icon that you would rate with a B+ or an A-. And it really is very, very well designed. There aren’t very many 1970s buildings in Germany like this; that display such consistency. But this was not the most important aspect for the investors. From their point of view the most important thing was to improve the building’s ecological profile. We really had to do some persuading, clearly laying out the reasons why we wanted to keep this wonderful aluminum façade. In the end, we just replaced everything behind the outer plates – the insulation and insulating glazing etc. Today, these four-millimeter-thick aluminum plates would cost a fortune. And they will probably hold up for another one or two hundred years. This is also a form of sustainable construction. In the case of Poseidon House, we were working with very different materials. The façade was also far less expensive. In contrast to the Silberturm, Poseidon House is a typical investors’ building. There is also the fact that the new section of the building is based on a different layout to the old section. So we needed a façade that would accommodate these factors. And you can’t achieve that effect with stripes. You can’t simply switch from narrow stripes to wide ones. SCHUMACHER The façade is a building’s face. There’s no way around that. We always take the approach of generating an original but pragmatic solution based on the respective needs, not one that relies on special effects. We work with proportions and, when appropriate, we like to use glazed facades too. They are very aesthetically pleasing and also have advantages in terms of use. When it comes to ecological considerations things are often quite different. We then try to balance out the pros and cons with the aim of designing an element as important as the façade in such a way that it is distinctive but not overelaborate. Beyond all of the ecological certifications that exist today, our internal definition of sustainability is: long-lasting and attractive. And what is long-lasting and attractive when it comes to architecture? That is for the most part dependent on the use of good materials. So it is a question of the goods, the quality. Just consider the aluminum plates that cover the Silberturm. Furthermore, as regards the aesthetic qualities of architecture it is also imperative that a building is distinctive, but not too dominant. I’ll give you an example: Another of our projects, the Westhafenturm, is distinctive. But it doesn’t scream, “Look at me!” That is – at least from my point of view – the right mindset for most architecture. Of course there have always been architectural icons such as churches, palaces, and castles. But we only require a limited number of such buildings. When should a building be iconographic? What constitutes a church in today’s world? SCHUMACHER Over the past 10 to 15 years a great deal has changed in relation to facades. We initially thought about installing a double-skin façade. These have almost disappeared from our cityscapes. Glass was used a great deal back then; it was a very dominant material in modern buildings – something else that has now changed. Furthermore, we currently find ourselves in a process of constant change. At present, closed cavity facades are of particular interest to us, because here small doses of clean air can be pumped into the space between the panes. In our eyes, this is the best kind of façade right now because it requires very little cleaning and provides the most effective acoustic insulation, while parallel opening windows still allow for natural ventilation. Its use in this combination is a first for Germany. SCHUMACHER The energy expenditure is minimal, negligible even. But of course this factor also has an influence on the overall costs. I’m sure that we will have to gain more experience in this area in the long term. However, our previous experience with membrane roofs, which likewise require a minimal supply of air, tells us that in relation to other problems we might face during construction this is rather unimportant. It is always imperative to take various factors into close consideration before deciding for one façade over another. We generally start with 10 to 15 different façade models, all of which are then assessed down to the smallest detail. SCHUMACHER No, we will be using the closed cavity façade for the first time. We always find ourselves at a certain point within the development of technology. You encounter and recognize new possibilities and contemplate how they could alleviate one problem or another. With Poseidon House, for example, we were not able to use a deep-set façade. Closed cavity facades are relatively shallow but still offer a high degree of acoustic protection, which plays a major role given the building’s location on a busy road. Architecture is never an entirely new invention. But you always strive to advance some aspects and reconcile them with the desired formal effects and urban-planning considerations. While on this subject I would like to mention another building that demonstrates another aspect of refurbishment and upgrading: the Consulate General of the United States in Frankfurt. Designed by Skidmore, Owings and Merrill, this is a typical modern building from the 1950s. It was once an icon and turned the architectural scene here in Frankfurt upside down. These kinds of curtain walls were top class at the time – the ultimate in façade design. But it has now aged quite considerably. If you take a look at older photos of the Consulate you will see that the façade is made of 50-millimeter-thick aluminum profiles, whereby any condensation water runs down, and each window contains a ventilation ring, a kind of propeller. But the façade has warped over the years. It’s had it, it’s now useless. And this raises the question: What are you going to do with it now? Monument protection seeks to safeguard the authenticity of a building, triggering an interesting discussion about what makes a building “authentic” from a present-day perspective. We have always said that our primary concern is to redeem the spirit of a building for the present day. However, aside from a few concrete pillars, very little of the original building was preserved. But the spirit, or so I think, is still there. I bet that if Louis Skidmore were still alive and able to see the building as it looks today, he would say: That is exactly how we wanted it to be, I’m pleased that it’s still standing. That is really great. And on top of it all, in terms of its ecological profile, it has been given a two-liter engine. And there you have another project where it wasn’t about our signature.
THOMAS WAGNER: MR. SCHUMACHER, WHAT IN PARTICULAR ATTRACTED YOU TO THE PROJECT TO REDESIGN THE FORMER POSEIDON HOUSE? WOULD YOU HAVE PREFERRED TO DESIGN A NEW HIGH-RISE, HAD YOU HAD THE OPPORTUNITY TO DO SO?
BEFORE WE COME TO THE MORE TECHNICAL ASPECTS, CAN YOU TELL US SOMETHING ABOUT THE REASONING BEHIND THE DECISION TO GET RID OF THE OLD PINSTRIPE FAÇADE THAT VISUALLY LENGTHENS THE BUILDING IN FAVOR OF A DESIGN SOLUTION THAT INSTEAD SERVES TO BIND THE ARCHITECTURAL ENSEMBLE TOGETHER? DID THE AESTHETICS OF THE OLD FAÇADE NOT CORRESPOND TO YOUR SIGNATURE LOOK?
LET’S LEAVE THE QUESTION OF A “SIGNATURE” ASIDE FOR THE MOMENT. WHEN I LOOK AT YOUR PROJECT, AND WE ARE TALKING ABOUT FACADES HERE, I GET THE IMPRESSION THAT YOU – AND I MEAN THIS IN A POSITIVE SENSE – PLACE A GREAT DEAL OF VALUE ON THE FAÇADE’S DESIGN. DOES THE FAÇADE HOLD A PARTICULAR RELEVANCE FOR YOU AS PART OF THE BUILDING? DOES IT PLAY AN INSTRUMENTAL ROLE EVEN IN THE EARLY DESIGN STAGE?
WHY DID YOU CHOOSE THE “CLOSED CAVITY FAÇADE” FOR POSEIDON HOUSE IN PARTICULAR? WHAT ARE ITS STRONG POINTS? HOW DOES THE CLOSED CAVITY FAÇADE DIFFER FROM OTHER FAÇADES, ALSO FROM AN ECOLOGICAL PERSPECTIVE?
DOES PUMPING AIR INTO THE CAVITIES CONSUME A LOT OF ENERGY?
HAVE YOU ALREADY WORKED WITH THIS KIND OF FAÇADE ON OTHER CONSTRUCTION PROJECTS?
