Six years ago, Bayer Group, the $30-billion chemical, pharmaceutical, polymer, and agricultural products manufacturer, took steps to further globalize operations and restructure its business to put greater emphasis on its pharmaceutical line. The company that introduced aspirin to the world in 1897 envisioned the day when sales of its prescription drugs would constitute half the company's business.
As part of this restructuring, then-chairman Manfred Schneider and his executive team took a look at the image portrayed by the company's headquarters in Leverkusen, Germany (population: 162,000), where an enormous illuminated sign in the shape of a "Bayer Cross" aspirin tablet greets visitors. The company's original headquarters, a four-story landmark masonry building along the main street of the campus, naturally would remain, but it was decided that an outdated 35-story headquarters tower had to be replaced, even though it was barely 30 years old, to signal the start of "the new Bayer."
In the spring of 1997, the company held a competition limited to Italy's Renzo Piano, Japan's Kisho Kurokawa, Austria's Gustav Peichl, Germany's Helmut Hentrich and Erich Schneider-Wesseling, and two American firms, Richard Meier & Partners, New York, and Murphy/Jahn, Chicago. The following April, Bayer awarded the project to the Chicago firm, chaired and directed by Helmut Jahn.
Of course, Jahn was hardly an unknown entity in Germany. Born in Nuremberg in 1940, he was educated at Munich's Techsnische Hochschule and the Illinois Institute of Technology, under Ludwig Mies van der Rohe. In 1967, he became an assistant at C.F. Murphy Associates, moving up to executive vice president in 1973. Within eight years, he became a principal of the newly named Murphy/Jahn, rising to president and CEO in 1983.
Under Jahn's charismatic leadership, Murphy/Jahn strung together numerous marquis projects in the eighties and nineties, both in the U.S. and abroad — Chicago's James R. Thompson Center (1985), United Airlines Terminal One at O'Hare International Airport (1987), the Hyatt Regency Roissy in Paris (1992), Singapore's Hitachi Tower (1993), and the European Union Headquarters in Brussels (1998).
In Germany alone, by 1998, Murphy/Jahn had already completed Frankfurt's Messeturm (1991), the Mannheimer Lebensversicherung in Mannheim (1992), the Munich Order Center (1993), Munich's Hotel Kempinski (1994), and Stuttgart's Pallas (1994). The firm was hard at work on the Munich Airport Center (1999), and, perhaps topping them all, Sony Center (2000), located on Potsdamer Platz, within sight of what was once the Berlin Wall.
To meet Bayer management's goals — that the new headquarters be cost-effective, environmentally friendly, and low-rise — Jahn and his team had a number of architectural and engineering challenges before them.
Clearing the hurdles
According to Murphy/Jahn principal John Durbrow, who, along with principal Rainer Schildknecht, implemented the project from Jahn's conception, the Building Team had to leap three high hurdles.
The first, at the macroscopic level, had to do with siting the structure to take advantage of (and pay homage to) the adjacent Carl Duisberg Park, named after the Bayer industrialist who planned and developed the Leverkusen site in the late 1800s.
Complicating the task of engaging the park was the need to maintain its linear relationship to the complex's main street, Kaiser Wilhelm Allee, which would provide access to the new headquarters.
The solution that emerged from Jahn's hand proved to be both elegant and practical, as the overhead photo on page 59 shows — a kind of partial crescent with its ends lopped off, bifurcated by a four-story atrium space. The glazed entry hall provides access between the public street to the north and the private park to the south.
Nestled in the south courtyard, within the folding ends of this semi-ellipsis, is a circular reflecting pool, 25 meters in diameter, designed by Wolfgang Schrötter. Laid out in the familiar shape of the Bayer Cross, it is internally luminated. On the north side, a pergola extending the length of the building and running parallel to the street connects at the entry hall, creating an easily recognized protected passage to the headquarters structure.
The original design of the pergola called for the use of carbon fiber as the structural element, but budget restrictions forced the Building Team to revert to steel. The structure is covered by polycarbonate louvers with integral dichromatic film; the film coating changes color depending on the angle of the light and projects the colors onto the white driveway below.
The structure consists of a concrete skeleton with a minimum number of sheer walls. The exposed concrete slabs of the office floors are thermally activated by means of a network of pipes through which cooled or heated water flows, making the floor and ceiling slabs a component of the heating/cooling system. The underside of the ceiling is structured with wide coffers, which saves weight. The coffers are fitted with special light fixtures, which act as reflectors.
The second hurdlehad to do with the roof. Durbrow says the design team wanted to make sure the building could keep up with technology improvements; after all, the tower had become dysfunctional in only 30 years, which is unacceptable in European terms.
To reduce the possibility of obsolescence, the roof structure above the top office floor was configured as a two-way grid mesh of welded hollow-steel sections, supported on steel columns. The steel grid also spans the entry hall and is carried by slender, tapered columns.
The original plan called for switchable glass panels to be installed, but they proved uneconomical under current energy pricing. Instead, fritted glass panels that also serve as an acoustic and insulation barrier were set into the steel grid in a cellular pattern. According to Durbrow, this will allow the panels to be replaced at the point where switchable glass or even more-advanced solar panels become cost-effective. "We would love to see that," he says. For the entry hall, specially fritted glass cells were installed to control solar heat gain.
Insisting on glass
The third hurdle, and the one that most shaped the structure, had to do with Jahn's insistence on the use of glass for the façade — a stipulation that Bayer management was somewhat ambiguous about.
On the one hand, says Murphy/Jahn's Durbrow, Bayer is "incredibly security conscious." A glass building seemed to invite security problems, but tests were conducted that convinced Bayer executives that the building could be safe without having to look like a bunker. "This building proves that you can do a high-security building with glass," says Durbrow.
On the other hand, Bayer management was open to using glass, as long as it met the company's strict environmental requirement. Durbrow says this, too, defied conventional wisdom. "Most practitioners out there don't believe you can do an energy-efficient building with all glass, but Bayer is an energy-conscious company and they supported glass."
Working with structural and façade consultant Werner Sobek, of Werner Sobek Ingenieure GmbH, and energy consultant Matthias Schuler of Transsolar Energietechnik GmbH, both of Stuttgart, the Building Team developed a twin-shell façade. The low-iron laminated glazing on the outer shell and the insulated low-iron, low-e high-performance glass on the inner shell enable natural ventilation and protection from the elements. Between the glass panels are shades, which, like venetian blinds, can be regulated through control systems. The inner windows can be opened manually, in which case the mechanical systems are overridden.
At the south face, the façade is shingled to allow for better natural airflow when it's hot outside. Operable flaps at the gaps of the shingles allow for central control. The outer shell of the north face is straight. At the end walls and in the entry hall, fixed stainless-steel mesh provides sun protection. The entryway itself is tempered by waste hot or cold air, depending on outside temperature.
The façade's interactivity with its environment emulates the adaptability of the human skin, says Murphy/Jahn's Durbrow. "The skin is a building entity that responds to changing conditions and makes the building comfortable and responsive to those conditions."
Integration of the control systems with the glass façade also eliminates the need for finished materials. "Once you strip away all these overlays and use materials that are fundamentally the basis of the building, you start making a building that's economical," says Durbrow.
In fact, the increased thermal performance of the building enclosure reduces expected heating demand to a level 30% below the requirements of the new German energy code, according to Durbrow.
On the hottest days in northern Germany, when temperatures might reach 32 C, the double-shell windows reduce cooling needs by 5-6 C. A system of integrated plastic piping, which is connected to water beneath a nearby river, provides a natural cooling source, even when the water temperature is only 15-18 C. A conventional system would require a cooling air temperature of 6-8 C to condition the building.
The integrated building systems allowed the Building Team to put the mechanical systems (with the obvious exception of the elevators) on the outside of the building, rather than at the core, which has the effect of lightening the entire structure and opening up the building.
"We're trying to blur the distinction between interior and exterior, not just in terms of transparency, but also in terms of quality," says Durbrow. The views through the building to the exterior, either southward toward the park or northward to the landmark structure, can be quite striking.
"The laws of physics have never changed," he says. "The control systems make this a naturally ventilated building that will maintain a comfortable level" for occupants and visitors.
Occupied since April 2002, the $50 million headquarters will eventually house some 300 executives and staff on four floors, with underground parking for 152 cars and meeting, conference, and dining facilities. The office tower will be demolished sometime this year.
Currently, Murphy/Jahn does three-quarters of its billings outside the U.S. Already on the agenda: an exposition center in Shanghai and an airport in Bangkok.