The Steiff factory and the birth of curtain walling

The question of what building in history has the first curtain wall hides a tough academic battle. Here - as almost everywhere - Europeans and Americans diverge. I don't have a strong favourite. What I have is a list of the first curtain walls erected before 1950 that matter to me; and they happen to be located at both sides of the Atlantic.

Among the Europeans, the Fagus headquarter by Walter Gropius, built in 1911, is celebrating its first 100 years now. Among the Americans, the Halliday building in San Francisco (1917) is a must; same as the Equitable Building in Portland (1946), a forgotten jewell from Pietro Belluschi. Now that I think of it, it would be good to re-visit most of these great oldies in future posts.

The east block from 1903 is the front pavilion to the left. The others were built between 1904 and 1908. Picture from the early 1920s.

This post is devoted to one of the first real curtain walls (not a shop front or a wintergarden) ever built, the east block at the Margarete Steiff AG factory in Giengen, erected in 1903. One thing can be said for sure: this was the first double skin facade ever built and - not surprisingly - it had to be located in Germany. Most of the information for this post comes from a paper whose title couldn't be more clear: "The invention of glazed curtain wall in 1903 - The Steiff toy factory". The paper was presented at the 3rd International Congress of Construction History (Cottbus May 2009) and was written by A. Fissabre and B. Niethammer from RWTH Aachen University. More information about the Steiff factory can be found at the Docomomo Webpage on the building.

Europe’s most celebrated soft toys, the teddy bears with a button in their ear (‘Knopf im Ohr’) are still manufactured in this all-glazed factory building located in the small town of Giengen, 32 km north-east of Ulm. Margarete Steiff (1847-1909), a native of the town was partially-paralysed at the age of 18 months, but from a dressmaking studio in her father’s house she established a successful company making felt toys. Her nephew Richard Steiff was largely responsible for the company subsequent growth. 

The original factory building as it is today. Note the diagonal bracings at the large elevation.

Between 1902 and 1903 Richard Steiff took two revolutionary steps: to include bears (sitting bears to be precise) as part of the company toys portfolio and to design a new factory building to cope with the increasing international demand of felt toys.


Teddy bears for the American market were in fact the reason behind the construction in 1903 of a new iron and glass building, 30m long, 12m wide and 9.4m high, with an outer shell consisting of a continuous double-glazed wall and a flat roof. The three floors within are supported on iron lattice-work columns. The iron castings and forgings were designed and provided by Eisenwerk Munchen AG, a German contractor. The east building was subsequently extended with two more pavilions between 1904 and 1908, built in timber structure for economic reasons but all with the same double glazed facade. 

Richard Steiff's intention realised: an all-glazed, well-lit building to increase productivity in toys assembly

Inner view of the Fagus office wing, Gropius 1911

Look at the image above, and compare it with similar images of the Fagus factory in Alfeld by Gropius, to be built only eight years later. In Alfeld they made shoe trees, here in Geingen they made felt toys. Both activities required natural light. Alfeld is located at the north of Germany, Geingen is at the sunnier south. Natural light inside the Steiff factory is everywhere; if it were not for the clothings and the bulb lamps the image above could be almost contemporary. Look at the curtain drapes at the facade corners: they were there to protect from excessive sun radiation in summer.

Was Richard Steiff (the company founder's nephew) interested in a brand new industrial aesthetic or was he looking for an engineering ideal? Clearly not at all. He was a toy industrialist himself - he was looking after a continuous workshop plan, well illuminated, where productivity could raise and costs be kept under control. He was also in a hurry: in 1902 the company had received a first order of 3,000 teddy bears from a client in the USA, and subsequent orders were expected. More production space was needed but it had to be efficient, well lit and built quickly.

Richard Steiff with a teddy bear

Richard may have taken over some constructive ideas from his father, Friedrich, who was employed in the building sector. According to the paper  by Fissabre and Niethammer, Friedrich Steiff might have been influenced by new iron-glass constructions when he visited the Great Exhibition in Chicago in 1893. Upon receiving these ideas from his father, Richard did not only try to realise them but also to improve them. Maximising light was not an easy task as the planning authorities feared workers would go blind in a glass house. But the permission was given and construction could finally start.

Richard Steiff contracted the Eisenwerk München AG company to design and build the structure of the new factory. It remains unclear who proposed and decided it, but steel was the obvious material for a quick and fire-proof structure. The plans and details of the riveted and wind-braced steel frame were drawn by Eisenwerk München, as shown in the plan drawing shown here below. The three-storey loft, covering an area of 12 x 30m, has a slightly inclined single-pitch roof made of galvanised iron sheet. Inside it is divided in three naves each formed by five bays, punctured by rows of six load-bearing columns each.

Second floor plan as shown in the building-permission documentation, 1903. Note the L-shaped ramp for Ms Steiff's wheel-chair extending from bottom left up to top right.

The main structure of the building (located at the corners) consists of four L-shaped external pillars, riveted on several plates and angle sections. They are linked at the bottom with a lattice truss running around and set in concrete, thus guaranteeing the solid fastening of the frames. The lattice truss is also the basement of nine facade columns of I section set in each of the longitudinal walls, transmitting the perimetral forces onto the ground. The intermediate and short-side facade columns are composed of two U-shaped beams, conntected by small sheet metal streps (see images of the interior above and of the construction below). 


The load-bearing structure is reinforced by two long diagonal braces on each side of the long facades and cross-butressed ceilings at each floor level. This composition provides three-dimensional stability with a minimum dead load. Prefabrication and dry-fix connections are a fundamental part of the concept, a combination between Marcel Lods and Mero structures but built fifty years before. Even the Maison Dom-ino concept by Le Corbusier would come much later, in 1914-15.

Construction site in 1903. Note the four corner columns, the nine longitudinal pillars above the lattice truss and the intermediate set of six columns each. The top beams and the diagonal bracing are not instaled yet.

Now it's time to talk about the envelope, the really revolutionary innovation in this small building. The external cover consisted of a double skin façade on all elevations. The inner glazing skin goes from the upper edge of the floor to the lower edge of the ceiling, whereas the outer façade covers the total height of the building. If the inner skin could be understood as a large glass shop-front, not dissimilar to other examples in New York, Chicago or Berlin, the outer skin is nothing but a pure curtain wall. It floats above the facades suspended from the top level; it runs continuously around all three floors, it is attached to the columns to transmit wind loads, and it was conceived as a cavity between two transparent skins to improve its thermal performance whilst allowing natural light.

The columns are located inside the air cavity

The facade had been planned from the very beginning as a double-skin construction for heat insulation. The thermal insulation is achieved through an air cavity of around 25cm floating above the envelope. Air exchange is possible by opening box-type windows in every floor, which don't interchange air with the cavity. Additionally, the building was equipped with a low-pressure steam heater - new at the time - that kept the internal temperature stable in winter.

Corner detail and section / elevation, taken from Glass Construction Manual, Schittich et al 1999

What about summer conditions and solar heat radiation? It is clear that the workers did not become blind due to excessive light, but they surely were not happy working in summer under external high temperatures, equally high inside the building. How could solar radiation be mitigated? First, the glass is not transparent but matt, a cheaper version at the time. Matt glass has a slightly lower solar factor. Second, the factory owners used a combination of curtains and cross-natural ventilation to keep temperatures at least not higher than the outside ones. Air conditioned, already invented by Carrier, was of course not an option here, although ventilators were installed later on. It is ironic that exactly the same problem and the same 'natural' mitigation strategy was followed at the Crown Hall building in the IIT campus in Chicago, many years later. Mies van der Rohe was simply learning the same hard lesson again.

Vertical section of the double skin facade, taken from Fissabre & Niethammer 2009. Ech glass pane is 3mm thick. The cavity was communicated along the whole height.

One last detail that struck my attention when preparing this post: where are the stairs? As the plan above shows, there seem to be no stairs inside the factory space. Instead, a ramp was designed that, starting from the ground floor, provided access to the first floor and to the second one from the outside. The main reason for this unusual feature has to be found in the company founder and boss, Ms Steiff's handicap. I can imagine Ms Steiff as a strong minded woman, travelling up and down the ramp in her wheel chair. But there is a second reason, also quite practical. Building permission is given (and taxes are paid) based on the built covered space. A nice internal stairbox would have detracted a noticeable percentage from the net usable area. An external ramp, especially if it was required by a handicapped person, was an excellent alternative that had no impact on the inner space. Again, German passion for efficiency at its most!

The ramp at the back of the Steiff factory providing access to the first and second floors. Picture taken around 1903-04.

What was the influence of the Steiff curtain wall in the European architecture? The hard truth is that there were no lessons learnt from this early example of curtain wall application, simply because nobody decided to pay any attention. Why was the Steiff factory so completely ignored at the time?

• First, because the project was not signed by an architect. We now know it couln't be otherwise: an architect would have considered the whole concept too unpalatable. It was not until Gropius developed what he had learnt working for Peter Behrens at the Fagus factory that light was made upon the curtain wall as a respectable facade solution. 
• Second, the place was not central to anything. Giengen is still today a nice small town, with a German mid-size industrial park devoted to toys and fire-proof systems. It was not in Berlin, the Rühr or Frankfurt.
• Third, the company was not AEG or Messerschmidt. Steiff is well-known today but only among toy collectors. It was completely unknown at the beginning of its growth in 1903.

Scheerbart (left) and Bruno Taut at the Glass House, 1914

All said, it is a real pity (or a shame) that architectural critics were so blind about what was happening around them. Sigfried Giedion was too young, Muthesius or Tessenow were too interested in the handcraft work to notice about steel, glass or modern factories. The glass guru of the time, the poet Paul Scheerbart, would not write his very influential "Glasarchitektur" until 1914. And by then things had taken another direction. In summary, Richard Steiff was not the right man, not in the right place, and definitely not in the right time to become influential. He had arrived too early.  But he still deserves a big part of the credit. Now we know.

Open | Close: the new Scale series by Birkhauser

The Birkhauser construction books are a source of never-ending information, that grows larger every year. Some may criticize the fact that authors and themes are too German-oriented, understandable for a Basel-Berlin located publisher. But truth is, in my opinion, that if Birkhauser did not exist, we would miss it - and a lot!

There are many more books there apart from construction. In architecture the list is long and with some big names (Le Corbusier complete works to name just one). But that doesn't make Birkhauser unique: their uniqueness in the world publishing scene is their capacity to push the best known specialists in construction to write, to draw and to expand the knowledge of world readers - in spite of the German touch, or maybe because of it?

A friend has brought to my attention a book from 2010, titled 'Open | Close. Windows, doors, gates, loggias, filters' This is the first book of a collection called Scale. The second book of the series will be released shortly, 'Enclose I Build'. According to the Editors' foreword, 'The Scale series (...) provides illustrations at various different scales and with various degrees of abstraction, wich demonstrate the interrelation of space, design and construction' Judging by the first book of the collection, I would say that the degree of abstraction is a bit too high, and the technical scale is somehow lost in translation.

Open | Close examines architectural openings, from idea to implementation. The authors did not see the need to have a Contents page, which I see as a bad decision, so here it goes: Introduction - Windows - Filters - Doors and gates - Case studies - Appendix. I was intrigued because Loggias, one of the promises of the title, are not a chapter: in fact, loggia is a word almost non-existing along the book, apart from the title. A real pity.

The Introduction is poetic to say the least. Issues covered here range from 'Atmosphere' to 'Passageway, threshold and entrance' to 'Spatial openings and intermediate spaces' to 'Ambience and materials'. Luckily it's not too long. The second chapter, Windows, is the longest and at least to me the most disappointing. Aluminium windows and plastic windows share one page of the chapter. Enough. Window hardware (that is, fittings and the like) deals with old drill-in hinges, cremones and espagnolettes used in ancient timber windows, but tilt and turn fittings (covering 85% of all windows installed in Germany, as we learn) don't have a simple illustration or a technical description. Another pity.

The third chapter, Filters, covers sun and glare control systems, shutters, blinds, curtains and screens. To say 'covers' is a figure of speech: it runs short and passing through all these points. Chapter four is devoted to Doors and gates. Again: fire rated doors and emergency exits (both) can be dealt with in one page, one page meaning a short column of text and one big sketch. Chapter 5 brings us nine Case studies. We had been promised at the Introduction that the examples would be both practical and generally applicable. Maybe, but at least that's not the case with the conversion of the Moritzburg castle in Halle, by Nieto Sobejano. The project is one of the more interesting ones, the problem is that no openings are brought to our attention apart from one small section of a skylight in a nice roof construction - clearly not an opening in itself.

The book ends with an Appendix that includes several tables and information pages. If your project is in Germany and you don't speak German, it will be of help. There is a list of standards, most of them DIN and EN but not complete and maybe not too reliable either. DIN EN 12208, dealing with watertightness of windows and doors, comes under the heading 'Doors - Thermal insulation'. Would you say DIN EN 14351-1, the product standard for windows and external doors, the standard on which CE mark for windows is given, should be in the list, maybe under the heading 'Windows - Planning in general'? You got it: it's not there - nor anywhere else, but you can enjoy DIN 107 instead, titled 'Left and right designation in construction engineering'. A pity once again.

Then there is an 'Associations and manufacturers list'. All associations are German. No problem with that, but couldn't the authors (three architects from TU Darmstadt) do some Google digging and add the equivalent British, French and maybe US counterparts? Manufacturers are from... yes. Reynaers is in the list because they have an address in Gladbeck. Technal is not in the list - OK, too French. But Wicona, a great supplier from Ulm providing aluminium window systems all around Europe, is not in the list either! Why?

My friend paid 49,90€ for this book. I arrived too late to tell him that he should have invested less than half that quantity in buying another Birkhauser book, a much humbler one: Facade Apertures from the Basics series. Its cost? 12,90€. The amount of valuable information? Quite the same, with less nice colour images for sure. This - having arrived late with my advice - is the biggest pity indeed.

ThyssenKrupp Quarter facades: a giant's gentle skin

Some great buildings pass unnoticed below the radar of architectural intelligentsia. And not because they are small or built in lost places, but because they are too 'client oriented'. If a corporation is satisfied with their new HQ building, its architectural quality must have been low, or so the thinking goes. This post describes a recently finished great group of buildings - two times great, since they are both architecturally compelling and they perfectly reflect their owner and user's vision. If this group of buildings is interesting in a number of ways, one of them is the facade treatment, as I will try to demonstrate here below.

During several decades the architectural landscape of the Ruhr Valley towns in Germany has been dominated by neglected brown fields, industrial ruins and run-down postwar buildings. That is now becoming a thing of the past as architects from all over Europe complete their projects in the former coal-mining region.

The ThyssenKrupp Quarter in Essen is part of a 230-hectare downtown area known as the Krupp belt. The site, kept for years as a wasteland, is a historic place. In 1818, Friedrich Krupp founded a cast steelworks on the same spot, which his son Alfred turned into a global company. Railway tracks were produced here for the United States, and less exciting but quite effective canons were casted in the area for two world wars. It is a place in German history that triggers mixed emotions to say the least. A less known but more interesting tip for architects: the huge 'gerberettes' designed by Rice, Piano and Rogers for the Pompidou Centre in Paris were also built at the Krupp furnaces, not far from Essen. Krupp was the only company in Europe who stood to the challenge of producing the big cast steel pieces that were to play a significant role in the structural concept of the Beaubourg.

Thyssen­Krupp has built its new headquarters in this historic part of Essen at a total cost of 300 million euros. The technology giant, which employs 173,000 personnel in 80 countries, has no interest for skyscrapers. ThyssenKrupp’s chief expectation during the competition was that architects made the essence of its brand visible: transparency, innovation and far-ranging versatility. With the bulk of the masterplan finished this last summer, corporate culture and German industrial power welcome a new symbol. 

Chaix & Morel et associés (Paris) and JSWD Architects (Cologne) won the competition for the campus buildings and developed the ThyssenKrupp Quarter for a working population of 2,000 employees. There is ample space for them here. A 200 meter-long and 30 meter-wide pool forms an axis along which various buildings and generously laid-out boulevards appear. It is quiet around here, too. Cars disappear into car parks and subterranean garages around the plot. All deliveries are conducted below ground. Above this, 68 trees from five continents form a boulevard. There are large expanses of lush green lawn without bushes or perennials. The important aspects here are distance, silence and solemnity. Peter Drucker would have salivated in awe: this is the spirit of the new corporation, built to last.

The main building, known as Q1 and officially inaugurated in June, has a flexible facade layer made up of 400,000 stainless steel slats. This system aims to make air conditioning redundant. A weather station on the roof sends signals to a computer that steers the rotation of the facade slats. The design makes use of the material Nirosta, one of the concern’s branded products. ThyssenKrupp also aims to improve the cladding of high-rise buildings, and replace expensive aluminum profiles. To this end, the company has developed steel sheeting with a zinc and magnesium coating.

There are three elements that deserve to be described in more detail in this post: the glass mullionless curtain walls in the centre of Q1, the sunshades at the external office areas also in Q1, and the flat-rolled steel cladding of buildings Q1 (inside the atrium), Q2 forum, Q5 and Q7 (as the main facade cladding). Let's go with the description, one at a time.

Panoramic windows at the atrium
The large atrium area of Q1 shimmers as a result of its pearl-metallic gold color internal cladding.  But it is primarily the expansive volume of space that captivates. The 50 meter-high building, bonded from two L-shaped structures, is dominated by 'panorama windows', in fact two large tensed cable curtain walls. Both glass constructions are 28 meter high and 26 meter wide. The design and engineering of the panorama windows was done by Werner Sobek from Stuttgart. The facade contractor was Hefi Glaskonstructiv from Talheim, Germany.

View of the main axis pool through the panorama window at Q1

A steel pre-stressed cable net system holds the individual glass panes in place. Each double glass unit is 2.15m wide x 3.60m high, with clamps at the corners and mid height to connect it to the vertical and horizontal steel cables. Pre-stressing in two axes made it possible to eliminate complicated transitional details to the adjacent facade structures. In the vertical direction, with a grid dimension of 2.15m, the grid is composed of pairs of pre-stressed cables with a diameter of 30mm each. They are fixed to a three-story steel truss below the building’s 11th floor. The horizontal net structure, attached at the ends to the story floors, consists of one pre-stressed steel cable every 3.60m, with a diameter of 32mm. The vertical cable disposition in pairs allows the transfer of the glass self-weight via a force couple - tension and compression - into the pre-stressed cables. The horizontal pre-stress per story is 34 tons, while the vertical pre-stress connection is 2 x 15 tons. To transmit these forces the engineers from Werner Sobek chose carbon steel of grade S355. Compared with stainless steel, carbon steel displays a higher strength and a lower thermal expansion. The cables have a tensile strength of 1770N/mm2.

The structural solution followed here is quite similar to the Lufthansa Aviation Centre in Frankfurt, also by Werner Sobek, although in Frankfurt the only load-bearing elements are the vertically tensioned cables.

Atrium with panorama window to the left

The choice of glass was critical too: on the one hand it had to have solar control, while on the other it had to be clear with as little tinting as possible. To achieve the aim of maximum-possible transparency, a custom solution featuring insulated clear glass panes was selected. The structure is as follows: a) 12mm single-pane safety glass, b) 16mm inter-pane space, c) 2 x 8mm laminated safety glass with 1.52mm PVB film for solar control. The type of glazing chosen and the reduced support structure have resulted in an only 45 mm thick membrane that appears completely dematerialized. Despite being so thin, the glazed membrane met all thermal insulation requirements. I have not found any reference to argon fill in the glass cavity, but assume it is the case or the U-value would have been too high.

The images below show the section, elevation and concept details of the glass fixings.

ThyssenKrupp Q1 building: vertical section and panorama window glass elevation

ThyssenKrupp Q1 building: vertical detail of fixing at glass crossing. Two cables run vertical, one cable (sectioned) runs horizontal. All screw heads are embedded on the cast steel piece. 

ThyssenKrupp Q1 building: horizontal detail of fixing at glass crossing, and elevation detail of the external clamp. Two cables run vertical (sectioned), one cable runs horizontal.

The panorama windows viewed from inside

It’s not just the two panoramic windows that contribute to the amount of light that floods the atrium: there is also a large window opening in the atrium roof, supported by a cable net. Its dual-curved outer skin measures approximately 21 x 21m.

The technology of pre-stressed cable net facades is not new, and it's a very German one. If you are interested, there is a good summary in pages 235 to 243 of the highly recommended thesis by Mic Patterson, 'Structural glass facades: a unique building technology'. The first and still best known example of this glass wall system is the lobby of the Kempinski Hotel at the Munich airport, designed by Helmut Jahn and engineered by Schlaich, Bergemann & Parters. The hotel lobby was completed in 1993 and still looks amazing 17 years afterwards. The cable net grid in Munich is much smaller than the one in Essen, but there is only one cable per direction, making the knots less visually imposing than those of the ThyssenKrupp atrium. One could say that the Sobek version is more imposing in size and less innovative in the fixing details than its SBP's counterpart. But Munich was a much less rigid, monolithic glass, not an insulated screen. In any case, at least to me, the real interest of Q1 does not lay on the panorama windows, but on a much humbler element: the sunshades of the office space all around the building.

Sun-shading movable slats
Our industry has been strongly discussing for some years about the energy irrelevance of double skin glass facades. Their former advantage in reducing U-values has been equaled by the triple-glass units with argon-filled cavities and high-performant coatings developed in the last decade. On the other hand, g-value or heat gain coefficient (the % of solar radiation that penetrates through the glass) remains as a serious problem for office buildings in summer period. Renzo Piano was the first one in introducing the 'mediterranean double skin', that is, a continuous glass facade with a set of sunshades on the outside for solar protection. An energy simulation study presented by Mikkel Kragh and Annalisa Simonella from Arup Facade Engineering at ICBEST 2007 has got to the same conclussion: there is no direct correlation between U-value and overall energy performance in a building with high internal heat gains, as an office building. In other words, the main driver is exposure to solar radiation.

The best answer from a energy and daylight perspective, even in a cold climate as the Ruhr Valley, is to combine a lowish Uw-value (around 1,2W/m2ºK for example, achievable with double glass units and high-performant thermally broken profiles) with an effective sunscreen. 'Effective' here means a screen that reduces solar gains when there is direct solar radiation but lets daylight in when there isn't. That is, a moveable sunscreen. Et voilà: this is the solution applied to ThyssenKrupp Q1 facades.

Multiple image with fins at different angles from 0º to 90º

The sun-shading concept was suggested by the architects and developed by the Fraunhofer Institute for Solar Energy Systems in Freiburg. The energy study came out with a proposal to provide a constant horizontal overhang - useful for summer protection and as a catwalk - combined with a vertical set of twisting fins. The fins would twist to achieve an adjustable position between 0º (parallel to the facade: total direct radiation blocking) and 90º (perpendicular to the facade: maximum daylight penetration).

The great idea in this concept was to create a vertical fin made of horizontal cantilevered slats that were connected to a central stud, something similar to vertebrae in a spine. The cantilevered fins at each side of the stud can twist independently, as arms that rotate from widely open (0º) to parallel and intertwinned (90º). The final touch was to provide a shape for the fins that was non-rectangular, thus creating an interesting texture as the fins rotate along the day.
The sunshade elements have been manufactured by ThyssenKrupp Nirosta (the company branch for stainless steel) using a chromium- nickel-molybdenum stainless steel with high corrosion resistance called Nirosta 4404 (that is, EN 1.4404, equivalent to AISI 316L).

The movable fins from inside, with the horizontal catwalk

Each slat is ground on one side and sandblasted on the other. The slats thus appear to be matt or glossy depending on the point of view and incidence of light. The slat surface directs the incoming light indoors in such a way that the offices remain bright enough even if the sun protection is closed.

The manufacturing of the sun protection system must have been demanding. First, the metal strips were processed by ThyssenKrupp Umformtechnik, the group's automotive manufacturing unit. Then, Frener & Reifer, the facade contractor from South Tyrol mounted 116 to 160 slats onto each axis to form electrically driven slat packages. In the process, it was important that the slats remain movable in the center axis and react precisely to the signals of the electrical drive. It's funny that Frener & Reifer motto is 'Starting where others stop', completely adequate to this particular job. The facade contractors did also install the inner curtain wall, made with Schüco elements. Both skins in Q1, curtain wall and fins, are approximately 7,800m2 each.

The virtual animation at the Frener & Reifer page shows the movement game better than my words. The programming is really sensitive: the control system not only detects the seasonal sun position, but also knows what the current weather is like due to the data of a weather station located on the roof of Q1 building. On cloudy days, for example, all the slats will be turned outwards so that the sun shades remain open. Even when the slats are closed directly in front of the facade, employees can open the windows and access for maintenance is always possible.

There are in total a number of 1,600 motors to activate the fins movement. This seems as a maintenance nightmare, but it doesn't have to be so. Movable facade elements are more and more common lately, with motor costs going down and system reliability moving up every year.

This is a revolutionary design move, not in concept but in results: I suspect we will see many more moveable sun-shades in the near future. There is an interesting joint venture between Buro Happold and Hoberman, called Adaptative Building Initiative, that provides nothing but moveable facade elements to control solar gains and light levels at the same time.

External steel cladding

Sheet metal has long been considered a second rate cladding material – an impression the buildings of the ThyssenKrupp Quarter had to change. The final image of the buildings around Q1, finely glimmering in a champagne hue of metallic elements, consist of nothing other than sheets of steel.



ThyssenKrupp Quarter, Q2 Forum building facade clad in coil coated steel sheets.



Not just any sheet steel but a high-quality, fine sheet steel organically refined using a coil coating method. Fine sheet metal, coated using the hot-dip method, can be shaped, welded and painted. The 3m long and 0.67m wide, chamfered steel panels of the Quarter are resistant to wind, weather and UV radiation. Here, one percent of magnesium is added to the molten zinc for the fine sheet metal. As a result, improved corrosion protection is achieved with a thinner coating, which means that the valuable raw material zinc can be used sparingly.



Q2 Forum facade mock-up on site

The fine sheet metal, with a thickness of 0.8 to 1.2mm, is more affordable than a comparable facade element made of aluminum sheets of 3mm, at least so the ThyssenKrupp guys say. The material is called PLADUR ZM Premium steel; used as cladding for the walls of the atrium inside Q1, the interior of the ground-floor lobbies in Q2, Q5 and Q7 buildings, and the exterior facade areas on Q2 forum, Q5 and Q7. The material owes its appearance to a multi-layer coating in a color named Pearl Metallic Gold. Thanks to special pigments, the color shade of the surface changes depending on light conditions and the angle from which it is viewed. The term “Premium” refers mainly to the quality of the top coat, while the abbreviation ZM means that the surface of the steel is first protected against corrosion with a zinc-magnesium alloy coating before the paint system is applied. This alloy provides roughly twice the corrosion protection effect of conventional hot-dip galvanizing.


TKQ, Q5 and Q7 facades



It's fair to record that the façade area consultant for the Quarter has been Priedemann Fassadenberatung from Berlin. No information can be found at their Webpage about the project or their contribution though.

Let me finish this long post in silence. No more words - there have been too many! Just some selected images of Q1 and the sun-shading slats that struck me when I first knew about this project. In awe...