(continued)

In most places of the developed world, Pelli observes, the dominant construction system consists of a frame of steel or reinforced concrete that supports the floors, the roof, and the enclosing walls. The enclosure itself is made of several thin specialized, layers applied in the field: the exterior finish, physical protection, thermal insulation, waterproofing, vapor barrier, and interior finish.

The characteristics of this dominant system are still developing, and Pelli holds that it is the architect's role to develop the forms for a still-young architecture.

High-Tech Hut

Pelli believes that the key to finding a new mode of expression is to look to models of construction other than the load-bearing wall. And the paradigm he points to is the simple hut found in developing regions all over the globe.

"Today, our building system of enclosure is based on the primitive hut," says Pelli. Contemporary construction systems create buildings that are essentially like one-room structures made with frames of branches or cane, covered with thin, flexible enclosures of grass, skins, and textiles.

Pelli points out that these adaptable structures provide more shelter per unit of effort, and are more ecologically benign, than any other form of construction.

"It's the longest lasting construction system in the world," he says. "Walls and roof are one, decoration is two dimensional, through texture of materials and weaving.

"This tradition bears many conceptual similarities to our present system of frame and enclosure: An open frame that supports a lightweight enclosure, with exterior form provided by a two-dimensional surface that describes a three-dimensional volume, with distinct wall and roof elements."

The actual technology is far from the same, but Pelli believes that their conceptual similarities can help architects better understand our dominant technology of construction as we try to interpret it.

While contemporary construction is based on two equally important elements — frame and enclosure — Modernism concentrated primarily on the expression of the frame.

But for Pelli, "It is the enclosure that connects us with our environment and gives final form to our buildings. It is what we see. Expressing the structure on the exterior of our building has hallowed precedents, but this satisfies aesthetic, not constructive needs."

Nature of the Wrapper

A pivotal building for Pelli in his own evolution of expressive enclosure is Herring Hall at Rice University in Houston, Texas. In its design, Pelli had to respond to the opinion of the building committee that newer buildings on campus had not been as well received as the venerable Ralph Adams Cram buildings of the 1910s.

The committee asked Pelli if Herring could be a historicist building, a la Cram. "I told them that I agreed with their observations," about the new buildings, says Pelli, "but I didn't know if I could do it. Those are historical imitations, and that I wouldn't do."

Pelli's solution was to design a building rich in the material versatility of the Cram buildings, employing such materials as the warm, St. Joseph's brick that Cram used throughout the campus, spandrel glass, and glazed tile.

But while Cram's buildings express the weight of their load-bearing exterior walls, and are elaborately carved, the steel-framed Herring Hall is enclosed with a taut skin of brick and glass. The thinness of this enclosure is most obviously expressed on the columns in the loggia, which are brick on the outside face and steel on the loggia face.

The envelope expresses texture and depth not through carving, but through two-dimensional patterns on the skin. Entrances are defined not by carved portals, as in Cram's buildings, but through layered and folded surfaces.

"Herring Hall helped me to resolve a conflict in my mind," explains Pelli, namely, why so many buildings that are well received by the architectural community are not accepted by the public at large and do not fit their surroundings.

Herring Hall allowed Pelli to understand how to design a responsive building while remaining faithful to the consistent relationship between an aesthetic system and modern construction technologies.

Thin Metal Skin

Just as Herring Hall demonstrates how a nonbearing brick wall might be rendered as the thin envelope that it actually is, Pelli's exploration of other cladding materials has probed their distinct natures. In downtown Tokyo, for example, his firm's design for the NTT Shinjuku Head Office Building demonstrates the expressive possibilities of a thin metal skin.

The 30-story project occupies a triangular site that hemmed in the buildable area from all directions: elevated highways, surface roads, and subterranean vehicular routes virtually ring the site, and a pedestrian route crosses the site.

Buildable area was also limited by open public space requirements, microwave paths, a height limitation of 420 feet (127 meters), and, perhaps most form-defining, natural daylighting regulations. The buildable area of the site thus worked out to be a distorted triangle, within which Pelli also had to respect the best views from the site.

The building plan evolved as a gracious fan that opens up to the east and prevailing views. Tucked behind the arc, to the west, are the building's service spaces, elevator core, stairways, and mechanical rooms.

The arc accentuates the tautness of the east wall, making it appear as a shear, thin, stretched skin of glass and metal. It fully expresses the nature of the wall as a lightweight, nonbearing, tight enclosure of air-conditioned space.

The materials were chosen to express a high-tech, mechanistic image that is appropriate for a telecommunications company. The metal panels are aluminum, coated with a specially developed warm metallic gray fluoropolymer finish, obtained by adding copper-coated mica to the paint formulation.

The glazing is configured as long, horizontal openings to take advantage of the panoramic view. The windows are protected by four rows of projecting sunscreens at each floor level, which accentuate the horizontality of the windows and the tautness of the wall.

On the west side of the building, functions such as cores and mechanical spaces that do not require natural light are simply clad in metal, expressed as vertical stacks, but continue the horizontal striping of the sunscreens.

There is an oasis of a plaza at the ground level in front of the tower's curved wall. Across the plaza is a three-story special functions building that is clad in an elegantly detailed, tightly curved wall of Minnesota Stone. This wall has a rich ocher color that glows against the metallic gray color of the tower — a contrast to the sleek, uniform, industrial product.

Envelope Open and Opaque

In contrast to the thin metal-skinned NTT building, Pelli's design for the Owens Corning World Headquarters in Toledo, Ohio, is an interesting study of openness versus opacity, juxtaposing forms with seemingly solid shrouds to those that seem to virtually disappear.

The Owens Corning complex, organized around a central courtyard, is located near the heart of Toledo's business center, near the Swan Creek and the Maumee River. The building stretches out across the landscape, forming two basic components: the reception lobby and the workplace. These components are enclosed with opaque and open skins, respectively.

The reception lobby functions as the building's logo, a corporate symbol that one approaches on axis across a bridge. This element is composed of a curved roof form of bright orange porcelain enamel panels, penetrated with small clerestory windows.

While not literally opaque, the roof appears as a solid form. It rests on a black, opaque pedestal that defines the lobby space. This squat cubic form heightens the sense of mystery in entering the complex.

In sharp contrast, the workplace is enclosed with a virtually transparent envelope, creating an open-office environment that maximizes access to views and sunlight adjacent to a three-story glass atrium.

The glass envelope gently undulates to follow the site as it moves along the riverfront; it seems to express the flow of the water. The office building is clad in a ceramic frit-patterned reflective glass on the riverside and clear glass on the courtyard side to maximize natural lighting of the interior.

The Search Continues

As these projects demonstrate, Pelli's work can be viewed as a succession of approaches to a range of materials, detailing, and construction techniques that express how we build today in a range of materials: glass, aluminum, stainless steel, brick, thin-veneer stone.

"These are the materials that express most clearly what I believe to be the nature of architecture today," says Pelli, who evaluates the choice of material according to the appropriate expression of contemporary construction. In the case of multistory buildings it is the thin envelope.

"That's the way I believe that we will keep on building, so it is essential not only for my architecture but for architecture at large that we get on with the task of figuring out how to do an architecture that is expressive, versatile, and suitable to all the tasks of this marvelous art, and consistent with the way we build."

Cesar Pelli writes extensively about his own work in his book, Observations for Young Architects, Monacelli Press.

Michael J. Crosbie is a contributing editor to ArchitectureWeek and an associate with Steven Winter Associates, Inc.

Entrances of Herring Hall are defined by layered and folded surfaces. Photo: Greg Hursley In downtown Tokyo, the NTT Shinjuku Head Office Building demonstrates the expressive possibilities of a thin metal skin. Photo: Kanaeki Monma The arc accentuates the tautness of the east wall, making it appear as a shear, thin, stretched skin of glass and metal. Photo: Mitsuo Matsuoka Materials were chosen to express a high-tech, mechanistic image. Photo: Tohru Waki A special functions building of the NTT Shinjuku facility is clad in an elegantly detailed, tightly curved wall of Minnesota Stone. Photo: Tohru Waki The Owens Corning complex is located near the heart of Toledo, Ohio's business center, near the Swan Creek and the Maumee River. Photo: Timothy Hursley/The Arkansas Office The reception lobby composed of a curved roof form of bright orange porcelain enamel panels, penetrated with small clerestory windows. Photo: Timothy Hursley/The Arkansas Office The Owens Corning office building is clad in a ceramic frit-patterned reflective glass. Photo: Timothy Hursley/The Arkansas Office   Click on thumbnail images to view full-size pictures.