Contemporary Curtain Wall Architecture

ContemporaryCurtain WallArchitecture

Scott Murray Princeton Architectural Press

New York

Contents

Part III: Case Studies

Introduction

The New 42nd Street Studios

Platt Byard Dovell White

New York, New York, United States, 2000

Melvin J. and Claire Levine Hall

KieranTimberlake Associates

Philadelphia, Pennsylvania, United States, 2001

One Omotesando

Kengo Kuma and Associates

Tokyo, Japan, 2003

William J. Clinton Presidential Center

Polshek Partnership Architects

Little Rock, Arkansas, United States, 2004

Green-Wood Mausoleum


Brooklyn, New York, United States, 2004

LVMH Osaka


Osaka, Japan, 2004

Seattle Public Library

Office for Metropolitan Architecture

and LMN Architects

Seattle, Washington, United States, 2004

Terrence Donnelly Centre for Cellular

and Biomolecular Research

architectsAlliance and Behnisch Architekten

Toronto, Canada, 2005

Torre Agbar

Ateliers Jean Nouvel

Barcelona, Spain, 2005

Introduction

Part I: A History of the Curtain Wall as Concept and

Construct

1: The Chicago Frame and the Dilemma of the Wall

2: Visions of a Transparent Future

3: The Mid-Twentieth-Century Curtain Wall

4: New Directions and New Priorities

Part II: Performance and Technique

5: Curtain Wall System Design

6: Building Envelope As Selective Filter

7

8

10

24

30

48

64

66

74

81

83

86

94

100

106

112

118

126

132

140

148

154

162

168

176

184

190

198

206

214

222

230

236

244

250

257

259

262

Torre Cube

Estudio Carme Pinós

Guadalajara, Mexico, 2005

Netherlands Institute for Sound and Vison

Neutelings Riedijk Architects

Hilversum, the Netherlands, 2006

Skirkanich Hall

Tod Williams Billie Tsien Architects

Philadelphia, Pennsylvania, United States, 2006

Trutec Building

Barkow Leibinger Architekten

Seoul, Korea, 2006

Biomedical Science Research Building


Ann Arbor, Michigan, 2006

ATLAS Building

Rafael Viñoly Architects

Wageningen, the Netherlands, 2006

Blue Tower

Bernard Tschumi Architects


The Nelson-Atkins Museum of Art

Steven Holl Architects

Kansas City, Missouri, United States, 2007

The New York Times Building

Renzo Piano Building Workshop and

FXFOWLE Architects


Spertus Institute of Jewish Studies

Krueck + Sexton Architects

Chicago, Illinois, United States, 2007

United States Federal Building

Morphosis

San Francisco, California, United States, 2007

Yale Sculpture Building


New Haven, Connecticut, United States, 2007

The Cathedral of Christ the Light

Skidmore, Owings and Merrill

Oakland, California, United States, 2008

100 Eleventh Avenue



166 Perry Street

Asymptote


AcknowledgmentsBibliographyIllustration Credits

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Printed and bound in China

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Every reasonable attempt has been made to identify

owners of copyright. Errors or omissions will be corrected

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Editor: Laurie Manfra

Design: The Map Office, New York

Library of Congress Cataloging-in-Publication Data

Murray, Scott (Scott Charles), 1971–

Contemporary curtain wall architecture / Scott Murray.

p. cm.

ISBN 978-1-56898-797-2 (alk. paper)

1. Architecture, Modern. 2. Curtain walls. I. Title.

NA2940.M88 2009

721’.2—dc22

2009007097

Special thanks to: Nettie Aljian, Bree Anne Apperley, Sara Bader,

Nicola Bednarek, Janet Behning, Becca Casbon, Carina Cha,

Penny (Yuen Pik) Chu, Carolyn Deuschle, Russell Fernandez,

Pete Fitzpatrick, Wendy Fuller, Jan Haux, Clare Jacobson, Aileen

Kwun, Nancy Eklund Later, Linda Lee, John Myers, Katharine

Myers, Lauren Nelson Packard, Dan Simon, Andrew Stepanian,

Jennifer Thompson, Paul Wagner, Joseph Weston, and Deb

Wood of Princeton Architectural Press

—Kevin C. Lippert, publisher

The author gratefully acknowledges the generous support of the

Graham Foundation for Advanced Studies in the Fine Arts and

the College of Fine and Applied Arts at the University of Illinois

at Urbana-Champaign.

Introduction

Recent years have seen a growing interest among contemporary architects in the

innovative use of the curtain wall, which can be broadly defined as the non-load-bearing

building envelope that typically hangs like a curtain from a structural frame. In 2008,

a New York Times Magazine article on the proliferation of high-profile buildings with

custom architectural enclosure systems declared, “We are living in a golden age…for

facades.”1 Indeed, curtain walls are transforming not only the aesthetic experience of

cities but also the technical performance of buildings with respect to energy efficiency

and occupant comfort. In contemporary practice, the curtain wall presents a microcosm

of issues important to architecture: climate-responsiveness and energy use, intelligent

utilization of resources, advancements in digital design and fabrication, and the timeless

desire to create buildings and spaces that function well and engage the imagination.

This book aims to explore the curtain wall as both concept and construct, placing

recent work by leading architects into the contexts of past and future developments.

The curtain wall remains one of the most enduring concepts of modern architectural

theory. From its origins in the late nineteenth century, the non-load-bearing facade has been

an influential component of each phase of modernism, driving innovation in response

to new challenges. The phenomenon of the curtain wall—like its technological impetus,

the frame structure—is ubiquitous and malleable. Through the articulation of materials

and parts, it can make a building anonymous or iconic; it can make it an energy hog or an

energy generator; and it can profoundly influence how people experience and use archi-

tecture, to name just a few of the issues that architects face when addressing the broad

implications of material selection, detailing, and fabrication methodology.

Developments in contemporary architectural design are best understood within their

respective historical and technological contexts. Therefore, this book is organized into three

parts, corresponding to history, technology, and contemporary design. “Part I: A History

of the Curtain Wall as Concept and Construct” traces key milestones, from initial con-

ceptions to subsequent developments in modern architecture. “Part II: Performance

and Technique” discusses the materials and methods currently influencing the design,

fabrication, and installation of curtain wall systems. “Part III: Case Studies” provides

analyses of twenty-four significant buildings completed since 2000.

1 Arthur Lubow, “Face Value,” New York Times Magazine, June 8, 2008, 48–52.

Essay Title 8

Part I: A History of the Curtain Wall as Concept and Construct

1

4New Directions and Priorities

The Chicago Frame and the Dilemma of the Wall

Visions of a Transparent Future

The Mid-Twentieth Century Curtain Wall

2 3

10Part I: A History of the Curtain Wall as Concept and Construct

10

The Chicago Frame and the Dilemma of the Wall

1

1.1

1.1

Construction of the

Reliance Building’s

structural frame,

August 1894

11The Chicago Frame and the Dilemma of the Wall

methods. Whereas they formerly provided enclosure and structural support, the new frame presented an architectural dilemma. Freed of its load-bearing responsibilities, the exterior became a blank canvas. What should be the character of the new wall? What type of skin should enclose the skeleton structure? Although architects and engineers did not arrive at an immediate solution, the curtain wall eventually emerged as a widely accepted response. After more than a cen-tury of development, the frame structure and its corollary, the curtain wall, continue to dominate construction today.

From his perspective in the high-modern period of the 1950s, Rowe recognized the importance of Chicago’s late-nineteenth-century building boom and the advancements made during that period. In fact, he equates the relationship between his contempo-raries and the city of Chicago to that of the High Renaissance architects and Florence, Italy. The rebuilding effort in the years fol-lowing the Great Chicago Fire of 1871, which devastated the central business district, was remarkable. Within twenty years, the down-town Loop area was rapidly redeveloped with taller and taller buildings for which the city’s architects methodically explored radi-cally original methods of construction. This intense effort was driven in part by a popu-lation explosion: at the time of its incorpora-tion in 1837, the city had four thousand inhabitants; by 1850, there were thirty thou-sand; and by 1890, it surpassed one million.3 The city was quickly becoming an epicenter of commerce and culture. As density and land values increased, the economic

In his 1956 essay “Chicago Frame,” Colin Rowe characterizes the frame structure as a universal theme of mid-twentieth-century architecture, proposing it to be the “essence of modern architecture.”1 The late-nineteenth-century development of the frame structure— using columns and beams of concrete, iron, and steel as a replacement for traditional solid-masonry load-bearing walls—marked a major transformation in architectural design and construction, exerting substantial inlu-ence over the commercial and institutional architecture of cities, particularly Chicago, where, as suggested by the title of Rowe’s essay, architects and clients embraced the new technology early on. From its experi-mental manifestations in the nineteenth cen-tury to its proliferation through the present day, the skeleton-frame structure was signii-cant not only for its technical achievements and widespread dissemination but also as a catalyst for new conceptions of architec-tural form. One of the most inluential ideas derived from the frame structure is the modern curtain wall. [1.1]

Historian Carl Condit called the inven-tion of skeleton-frame construction “the most radical transformation in the structural art since the development of the Gothic system of construction in the twelfth century.” 2 The importance of this new technology extended beyond the physical frame; it allowed, perhaps even obligated, architects to reconsider the essential character of the exterior wall. Traditionally responsible for a wide range of aesthetic and technical tasks, the outer walls of a building were directly implicated by innovative structural

1.2 1.3

1.2

Leiter Building I,

Chicago, Illinois, William

LeBaron Jenney, 1879

1.3

Ludington Building,

Chicago, Illinois, William

LeBaron Jenney, 1891


The three Gage Group Buildings were designed to maximize daylighting for the client’s millinery workers. Sullivan was responsible for the design of the more elab-orate facade of the northernmost building, which in its articulation suggests a multi-story curtain hanging from the cornice. [1.5]

A comparative study of two late-nine-teenth-century Chicago ofice buildings— the Monadnock Block (1891) and the Reliance Building (1895)—is useful in understanding the impact of the frame structure and the eventual emergence of the curtain wall. Among the many remarkable aspects of these two very different buildings is the fact that they were both designed by the ofice of Daniel H. Burnham and built within ive years of one another. Considered together, the Monadnock Block and the Reliance Building illustrate an important shift in the concept of structure and skin.

A proliic architect and planner, Burnham was also responsible for overseeing the planning and construction of the 1893 World’s Columbian Exposition, and his ofice produced inluential city plans for Chicago, Washington, D.C., and San Francisco. Burnham always worked with a junior part-ner, and the common perception was that Burnham handled the business side of the irm while his partner directed the design process, with Burnham acting as consultant and critic.7 His irst partner, John Wellborn Root (of the irm Burnham and Root), was the primary designer of the Monadnock Block. Root began work on the Reliance Building, but following his untimely death in 1891, the irm was renamed D. H. Burnham

beneits of building taller were obvious. Financial demand converged with the com-mercial availability of elevators and advance-ments in structural framing, leading to the emergence of the skyscraper, which in turn had remarkable consequences for the building enclosure. 4

The work of a group of architects active in the 1880s and ’90s—who later became known as the Chicago School—deined this era of experimentation.5 Notable buildings from this group are quite numerous and include William LeBaron Jenney’s Leiter Building I (1879), in which timber girders and loor joists were supported by a grid of cast-iron columns, a common construc-tion method at the time. [1.2] A unique strategy was used at the exterior, however, where instead of a bearing wall, iron columns located just inside the enclosure carried gravity loads at the loor perimeter. These columns were clad in non-load-bearing brick piers, kept consistently narrow to maxi-mize the loor-to-ceiling windows. Also designed by Jenney was the ten-story Home Insurance Company Building (1885), con-sidered by many to be the irst modern sky-scraper,6 as well as the Ludington Building (1891), one of the irst all-steel structures. [1.3] Later steel-framed buildings, such as the second Studebaker Building (1896) by Solon Spencer Beman and the Gage Group Buildings (1899) by Holabird and Roche in collaboration with Louis Sullivan, feature enclosures that express the underly-ing frame structure more directly. [1.4] Beman’s Studebaker Building is dominated by large windows and iron-plate spandrels.

1.4

Second Studebaker

Building, Chicago,

Illinois, Solon Spencer

Beman, 1896

1.5

Gage Group Buildings,

Chicago, Illinois,

Holabird and Roche,

1899

1.6

Monadnock Block,

Chicago, Illinois,

Burnham and Root,

1891

1.7

Monadnock Block;

typical lower-, middle-,

and upper-floor plans

1.8

Monadnock Block

1.4 1.5


and Company and a new design partner, Charles B. Atwood, took responsibility for the inal design.

Burnham and Root’s sixteen-story Monadnock Block was, for a brief period, the world’s tallest ofice building. [1.6] Although in some ways unprecedented, particularly in height and in its lack of facade decoration, the building was archaic in terms of its structural technology. At a time when all-steel frame construction was considered the future of the tall building, the Monadnock Block was built using the traditional arrangement of solid load-bearing masonry walls at its exterior, with interior loor loads carried on cast-iron columns and wrought-iron beams. Although Root’s initial scheme called for a steel frame with an ornately decorated facade of multicolored brick and terra-cotta, the architect was directed by his clients, Peter and Shepard Brooks, to abandon ornamental embellish-ments and revert to a traditional masonry wall structure.8 Load-bearing masonry requires that the wall’s thickness increase in relation to a building’s height. The taller the structure, the thicker the wall required to carry its compressive loads to the ground, which in turn requires a heavier foundation to support the weight of the building. [1.7] This type of construction, as commonly used in Chicago, was considered to have a practical height limit of ten stories. The brick wall of the sixteen-story Monadnock Block is 72 inches (1.8 meters) thick at its base. The width of this massive wall, which reveals itself at its recessed windows, has an undeniably powerful presence that

1.6

1.7

1.8


built that were, as William Dudley Hunt described, “masonry to the eye but steel or reinforced concrete to the mind.” 10

Built just four blocks away and four years later, the ifteen-story Reliance Building is a striking departure from the Monadnock Block and a radical reinterpretation of the ofice-building facade. [1.9] Although critics at the time were apparently not enthralled—“It is hardly to be supposed. . . that even the designer will consider it a masterpiece,” Charles Jenkins wrote 11—the building was eventually recognized as a milestone accomplishment of the Chicago School. Writing about the Reliance Building several decades later, Condit claimed, “If any work of structural art in the nineteenth century anticipated the future, it is this one,” adding that “Atwood succeeded in developing almost to its ulti-mate reinement the modern dematerialized

evokes permanence and strength, but it also takes up valuable loor space, limits the size of the windows (and therefore the amount of natural light that reaches the interior), and was considerably less eficient than steel framing in terms of labor and time required for construction. [1.8] The weight of such a structure can also lead to problems of settlement. Although the Monadnock Block was designed to accom-modate 8 inches (0.2 meters) of settlement, over the years it settled more than 20 inches (0.5 meters).9 For these reasons, it was one of the last tall buildings to be built with solid masonry walls; however, architects did not immediately abandon the aesthetic of the brick wall. The transition to curtain wall construction was a gradual process, with an intervening period in which a great many frame-structure buildings were

1.9

Reliance Building,

Chicago, Illinois,

D. H. Burnham and

Company, 18951.9


curtain wall.”12 The facade is characterized by great expanses of glass arranged in the “Chicago window” fashion, with a large central pane of glass lanked by narrow oper-able windows. The glass is set nearly lush within surrounding thin bands of glazed-white terra-cotta cladding delicately articu-lated with Gothic-inspired ornamentation. [1.10] The client, William E. Hale, was deter-mined to have a thoroughly modern building, calling for abundant natural light, the latest elevator technology, full electric service, and a telephone in each ofice.13

It is perhaps dificult to grasp the impact that the Reliance Building must have had on Chicagoans in 1895. With their delicate white framing, the glass walls, alternately transparent or relective depending on the time of day and perspective, would have stood in stark contrast to the neighboring dark brick buildings. The speed of construc-tion must have been startling as well. Working with the engineer Edward C. Shankland, Atwood designed a riveted steel-frame structure, the top ten stories of which were erected in just two weeks, a pace unthink-able with traditional masonry structures. In plan, the steel columns are effectively masked from the exterior, incorporated into corners and projecting bay windows. [1.11] The effect is suggestive of the forth-coming modern curtain wall: a minimal, modular expression of the frame’s grid with an inill of large glass panels. The wall is simultaneously informed and inlected by the structural frame, yet is free of it. In later work, such as the Flatiron Building (1902) in New York City, D. H. Burnham and Company would return primarily to the more conservative Beaux Arts–inluenced style of the World’s Columbian Exposition.14 To modern architects, it would later seem that Burnham and Atwood had essentially turned their backs on the new dialogue between structure and skin that they initi-ated in the Reliance Building, leaving it to other architects to take up the discussion.

Both the Monadnock Block and the Reliance Building were designated Chicago Landmarks in the 1970s, and both are still in use today. The Monadnock Block continues to function as an ofice building, while the Reliance Building, following an extensive restoration in 1999, has been converted to a hotel. In a nod to its designers, the building

1.10

Reliance Building, wall

section, 1895

1.11

Reliance Building,

typical floor plan

1.10

1.11


The materials of the railway, cast and

wrought iron, gradually became integrated

into the general building vocabulary,

where they constituted the only available

ireproof elements for the multi-story

warehouse space required by industrial

production.16

Frampton also noted that the standard structural I-beam shape, ubiquitous in frame structures today, irst emerged from the typical railway section. Notable early uses of iron framing include two ground-breaking English mill buildings: the irst in 1792, by William Strutt, in Derby; and the second in 1796, by Charles Woolley Bage, in Shrewsbury. Each employed cast-iron columns carrying segmental brick arches. These were followed by the engineer Thomas Telford’s 1829 warehouses at St Katherine Docks, in London, which were built with iron framing encased in brick, reining the techniques used in earlier buildings, with incremental improvements over previous installations.

is now known as Hotel Burnham; its ground- loor restaurant is the Atwood Cafe.

The frame structure had reached an important turning point in Chicago in the late nineteenth century, when the availability of steel (a stronger alternative to iron), among other factors, opened up new possi-bilities at an unparalleled scale. While the concept of the frame structure was certainly advanced during this period, it was not invented then. An exhaustive history of the evolution of frame structures is beyond the scope of this work, but it is worth a brief digression to note some important precedents to the Chicago frame. Kenneth Frampton has delineated the progression of iron applications over the course of the nineteenth century in Europe and the United States, tracing its use from railroads and bridges to the roofs of market halls and arcades and eventually to the framing of fully glazed conservatories and exhibition halls, such as Joseph Paxton’s Crystal Palace (1851) in London.15 With the rise of industry came new uses for iron. Frampton wrote:

1.12

Haughwout Building,

New York, New York,

partial section, west

elevation, and floor

plan. John P. Gaynor,

1857

1.13

Haughwout Building,

south elevation

1.131.12


Of particular interest in the study of the modern curtain wall is the mid-nineteenth- century era of cast-iron architecture, typiied by the work of New York designer/builder James Bogardus, the pioneer of the multistory self-supporting cast-iron facade.17 Bogardus received a patent in 1850 for his construction system of manufac-tured cast-iron columns and girders bolted together to form a rigid frame, which he employed in commercial projects such as the four-story Laing Stores (1849) and a ive- story building at 254–260 Canal Street (1857), which is one Bogardus’s few surviving build-ings. He vigorously marketed the cast-iron facade as an eficient and adaptable system that was quick to erect, relatively inexpen-sive, and resistant to ire. The Haughwout Building (1857) on Broadway in New York City was designed by the architect John P. Gaynor to resemble a Venetian palazzo, and it illustrates the tendency, which was common at the time, to retain intricate his-toricist ornament even while deploying a new method of construction. [1.12 + 1.13] Still occupied today, the building was the irst structure to be served by a passenger elevator, installed by Elisha Graves Otis. Another striking cast-iron building, which Sigfried Giedion called one of the inest of this period and a forerunner of the Chicago skyscrapers,18 was the Thomas Gantt Building (1877) in St. Louis, Missouri (dismantled in the 1940s). [1.14 + 1.15] These cast-iron facades, with their clear articulation of large metal-framed windows and their system of modular units prefabricated and bolted together on site, clearly preigure the modern curtain wall.

At the turn of the twentieth century, architects continued to explore the frame structure and its dual implications for inte-rior space and exterior expression. In 1897, Frank Lloyd Wright designed the provoca-tive Luxfer Prism Skyscraper, an unbuilt plan for a ten-story steel-framed building with a gridded facade of slightly projecting loor-to-ceiling glass panels.19 In Belgium, the architect Victor Horta worked with iron and steel, developing a vocabulary expres-sive of the ductile nature of those materials. In his buildings, such as the Maison du Peuple (1899) and L’Innovation Department Store (1903), the grid is clearly expressed on the facade with thin iron elements framing large

1.14

Thomas Gantt Building,

St. Louis, Missouri, partial

section and partial floor

plan; architect unknown,

1877

1.15

Thomas Gantt Building

1.14

1.15


at the outermost surface of the building. With this erosion of the bearing wall, the frame made it possible to open up the facade, allowing for the placement of larger and larger windows between structural mem-bers, with the obvious beneits of increased daylight, views, and opportunities for venti-lation. The window remained a discrete unit, however big it became, serving as a transparent counterpoint to the opaque grid of structure that framed it. In the irst two decades of the twentieth century, archi-tects began experimenting with the possi-bility of separating the glass membrane of the window from the structural frame, trans-posing the glass from individual window to continuous wall. Walter Gropius described this phenomenon, writing that “as a direct result of the growing preponderance of voids over solids, glass is assuming an ever greater structural importance,” with the

panes of glass, but the frame is also shown to be adaptable, embellished now with the subtle curvatures of the Art Nouveau aesthetic.20 [1.16] It was also around this time that architects began designing frame structures with reinforced concrete on a signiicant scale. In Paris, Auguste Perret’s eight-story Rue Franklin Apartments (1903) used a system of reinforced-concrete con-struction that had been pioneered and pat-ented by the builder François Hennebique in the 1890s. [1.17] The building was one of the irst concrete buildings to use the structural frame itself (clad in terra-cotta) as the primary exterior expression, inilled almost entirely with glass.

Architects eventually began to question the standard coplanar positioning of struc-ture and skin. When the structural frame irst arrived to replace the solid bearing wall, it generally retained the wall’s position

1.16

L’Innovation Department

Store, Paris, France,

Victor Horta, 1903

1.17

Rue Franklin Apartments,

Paris, France, Auguste

Perret, 1903

1.16 1.17


metal mullions spanning vertically from loor to loor, subdivided into a grid of glass panels, the dimensions of which were deter-mined by available plate-glass sizes, and the integration of opaque spandrel panels where needed to mask the underlying struc-ture. A strategy similar to Gropius’s had been used in the fascinating Margarete Steiff toy factory (1903) in Giengen. Although uncon-irmed, it is believed that Richard Steiff, the grandson of the company’s founder, produced the design.23 In this instance, the structural steel frame is encased in a double-layer facade, with a continuous outer skin of glass panels set in iron mullions suspended in front of the structure and extending from ground to roof and from corner to corner, with a second wall of glass on the inner side of the columns. Apparently designed for purely utilitarian purposes—admitting ample daylight to the factory while mitigating the inherent thermal issues of single-pane glass— it stands as one of the earliest continuous glass curtain walls and a remarkable precur-sor to the modern double-skin facades that would proliferate nearly a century later.

In the United States, two early-twentieth-century commercial buildings were particu-larly innovative in applying the curtain wall concept at an unprecedented scale. In these buildings, the structural frame is set back entirely behind the plane of a glass-and-metal facade, which is suspended from the struc-ture in a continuous surface. The earlier and more obscure of the two is the Boley Building (1908) in Kansas City, Missouri, designed

walls becoming “mere screens stretched between the upright columns of this frame-work to keep out rain, cold, and noise.”21 The gradual improvement in steel and con-crete technologies, Gropius wrote, “naturally leads to a progressively bolder (i.e. wider) opening up of the wall surfaces, which allow rooms to be much better lit.”22

These concepts are evident in several industrial buildings constructed in Germany just after the turn of the century, perhaps most clearly at the Fagus Shoe-Last Factory (1911), designed by Gropius and Adolf Meyer in Alfeld an der Leine. [1.18] Exposed brick-faced concrete columns are recessed behind the plane of glass, revealing the wall to be a nonstructural “curtain.” Between each column, the curtain wall is articulated as a continuous, three-story-high vertical band passing uninterrupted beyond the edge of each loor slab. The wall, with its organizing grid of slender steel mullions, is divided into clear glass panels and metal spandrels, the latter corresponding to the location of loor slabs. At the corner, the structural column is eliminated altogether, allowing the glass planes to meet at a single corner mullion that is no larger than typical. By comparison, the Fagus Shoe-Last Factory makes the cur-tain wall at the AEG Turbine Factory in Berlin, built just two years earlier to the design of Peter Behrens (for whom Gropius had worked), seem old-fashioned and inelegant. In the Fagus building, we ind many of the elements that would eventually constitute the vernacular language of the curtain wall:

1.18

Fagus Shoe-Last

Factory, Alfeld an der

Leine, Germany, Walter

Gropius and Adolf

Meyer, 1911

1.18


revolutionary Hallidie Building became the irst large-scale urban building to feature an all-glass curtain wall.26 [1.20] An unbroken seven-story wall of clear glass panels (with no opaque spandrels) is suspended 3 feet (0.9 meters) in front of the column line. The glass is ixed within a grid of narrow steel mullions, with the occasional pivoting sash for ventilation. The structural system is a reinforced-concrete frame. At the edge of each loor slab, an upturned perimeter beam supports a thin cantilevered slab, which in turn supports the curtain wall and acts as a irebreak between loors. [1.21] The stark purity of the gridded curtain wall is mediated by several ornate ironwork cornices and ire escapes that loat in front of the glass wall. Polk’s client was the University of California (the building is named for Andrew Hallidie, a former regent of the university and the inventor of the cable car), and the unusual decision to use an all-glass facade was alleg-edly a response to a tight budget and an accel-erated six-month construction schedule.27 A review of the building published in 1918 in Architectural Record pointedly avoids any discussion of aesthetics, focusing instead on the practical beneits of increased daylight and loor space, as compared to traditional masonry walls with recessed windows. The Hallidie Building, this article understates, “possesses more than ordinary interest to architects.”28 It also uncannily anticipates future developments in modern curtain wall design.

Interestingly, there is no indication in Polk’s earlier work of anything similar to the groundbreaking Hallidie Building, which

by Louis Curtiss. The later and better known is the Hallidie Building (1918) in San Francisco, California, by Willis Polk. Each of these build-ings has at various times been identiied as the irst large-scale installation of the pure curtain wall concept. Each was built in the center of its respective city, and, like the Monadnock Block and Reliance Building, they mark an important shift in the develop-ment of the modern building envelope.

Curtiss’s six-story steel-framed Boley Building is believed to be the irst frame structure to use columns of solid rolled wide-lange sections rather than built-up mem-bers.24 [1.19] The separation of skin and structure is emphatic; a continuous wall of glass and steel is suspended from cantile-vered loor slabs, which extend ive feet (1.5 meters) beyond the columns. The curtain wall, primarily large sheets of plate glass set within steel mullions, includes painted steel-plate spandrels and is framed by a cor-nice and corner bays clad in white-enameled terra-cotta (similar to the cladding of the Reliance Building). Curtiss, who practiced in Kansas City from the early 1890s until his death in 1924, was an eccentric character who regularly communicated with the spirit world and was a fervent believer in the Ouija board.25 He was also an undeniably visionary designer. Though not particularly well received or understood at the time, the Boley Building was, in its structure and cladding, a clear precursor to the modern architecture of later decades.

Ten years after its completion, at a time when most building facades were signii-cantly less than 50 percent window, Polk’s

1.19

Boley Building, Kansas

City, Missouri, Louis

Curtiss, 1908

1.20

Hallidie Building,

San Francisco,

California, Willis Polk,

1918

1.19 1.20


Frampton considers the “unique triumph of Polk’s career.”29 As early as 1892, the architect had articulated an appreciation for innovation and a progressive stance regard-ing historic precedent, writing, “Standards in art are set by the best work of [the] ages, but no age. . . is compelled to take its beauty from preceding epochs. . . . We must neither depreciate nor imitate, but we should under-stand and originate.”30 There are also inter-esting connections between Polk and two other igures discussed above: Burnham and Curtiss. Before moving to San Francisco, Polk worked for a time in Kansas City, where he and Curtiss were both members of the Kansas City Architectural Sketch Club in the late 1880s and thus may have known each other personally.31 The irst commission of Curtiss’s career had been the design of the Missouri State Building for the 1893 World’s Columbian Exposition. And Polk was also associated with the irm of D. H. Burnham and Company for nearly a decade, which included a stint working in the Chicago ofice from 1902 to 1904,32 where he surely would have become familiar with the Reliance Building, the Studebaker Building, and other works of the Chicago School. Although there is no conclusive proof, it is interesting to speculate that such connections may have inluenced Polk’s design of the Hallidie Building. Along with the Boley Building, it was listed in the National Register of Historic Places in 1971; both are still in use today, dwarfed by surrounding skyscrapers that are built on the principles they pioneered.

At the Bauhaus Building (1926), which Reyner Banham called “the irst really big masterpiece of the modern movement,”33 the glass curtain wall is given its irst truly mod-ern articulation on a large scale. Designed by Gropius and Meyer, the Bauhaus complex is sited in Dessau, Germany, and includes a ive-story student dormitory wing, a three-story classroom wing, and a three-story work-shop block. The facade of each wing gives an indication of the function within: the dormi-tory has individual punched windows and balconies, the classrooms are marked by larger groupings of strip windows, and the collective loft spaces of the workshop are enclosed by a continuous glass curtain wall that is hung outside of the reinforced-concrete frame structure and spans the full height of

1.21

Hallidie Building, wall

section

1.21


the curtain wall of the workshop building. Though rebuilt to some degree, it remained in various states of disrepair until it was restored to the original design in 1976. In 1996, the entire Bauhaus complex was added to the UNESCO World Heritage List; today it houses the Bauhaus Dessau Foundation, a center for interdisciplinary design research.

If the frame structure can be considered a feat of engineering, then the curtain wall was architecture’s response, exploiting the frame’s potential to reconceive the building envelope, thereby transforming not only the face of the modern building but also the experience of space within. The early, incre-mental development of the curtain wall was infused with a spirit of experimentation and informed by a diverse set of ideas about new construction methodologies, new mate-rials, eficiency, mass production, and, as we will see in the next chapter, the expres-sive possibilities of glass.

the building. Perhaps the most striking ele-ment of all is the curtain wall itself, which is technically similar to that of the Hallidie Building but utterly free of any historicist ornament. [1.22] It clearly builds upon the architects’ earlier design for the Fagus Shoe-Last Factory while making certain reine-ments, including the elimination of opaque spandrels and the complete setback of the structure. With its steel mullions, pulley-operated vents, and repetition of standard-ized units, the Bauhaus Building curtain wall epitomizes Gropius’s concept of a new

architecture, characterized by rationaliza-tion, machine production, and a new spatial vision.34 Certainly not without controversy or technical deiciencies (such as condensa-tion on the single-pane glass and insuficient acoustic insulation), the curtain wall looms large as an icon of the modern movement and as an “emblem of the machine age.” 35 In 1945, an air raid on Dessau destroyed

1.22

Bauhaus Building,

Dessau, Germany,

Walter Gropius and

Adolf Meyer, 1926

1.22


is disputed by David Yeomans in “The Origins of the Modern Curtain Wall,” APT Bulletin, 32, no. 1 (2000): 13.

16 Frampton, Modern Architecture, 32. Frampton also quotes Walter Benjamin’s 1930 statement, “The rail was the irst unit of construction, the forerunner of the girder.”

17 Margot Gayle and Carol Gayle, Cast-Iron Architecture in America: The Signiicance of James Bogardus (New York: W. W. Norton, 1998). In the foreword, Philip Johnson cites Bogardus as an inluence on the work of Mies van der Rohe at the Illinois Institute of Technology.

18 Giedion, Space, Time and Architecture, 202.19 Wright would eventually become more

interested in working with the cantilever than the frame. For a discussion of the Luxfer Prism project’s role in Wright’s oeuvre, see Michael Mostoller, “The Towers of Frank Lloyd Wright,” Journal of Architectural Education, 38, no. 2 (Winter 1985): 13–17.

20 The historian William J. R. Curtis calls the facade of the Maison du Peuple “every bit as ‘radical’ as Sullivan’s contemporary skyscraper designs in Chicago,” in Modern Architecture Since 1900 (London: Phaidon Press, 2005), 56. First published in 1982.

21 Walter Gropius, The New Architecture and the Bauhuas (Cambridge, Mass.: MIT Press, 1965), 26–9.

22 Ibid., 26.23 Christian Schittich, et al., Glass Construction

Manual (Basel: Birkhäuser, 1999), 25.24 Fred T. Comee, “Louis Curtiss of Kansas City,”

Progressive Architecture, August 1963, 128–34.25 Ibid.26 Keith W. Dills, “The Hallidie Building,” Journal of

the Society of Architectural Historians, 30, no. 4 (December 1971): 323–29.

27 Nory Miller, “Down and Dirty in 1917,” Progres-sive Architecture, November 1981, 108–9. The original color scheme of the building was blue and gold, the colors of the University of California.

28 MacDonald W. Scott, “A Glass-Front Building,” Architectural Record, October 1918, 381.

29 Kenneth Frampton and Yukio Futugawa, Modern Architecture: 1851–1945 (New York: Rizzoli, 1983), 194.

30 Willis Polk, “A Matter of Taste,” Wave, Novem-ber 12, 1892, 16. As quoted in Richard W. Long-streth, On the Edge of the World: Four Architects in San Francisco at the Turn of the Century (New York: Architectural History Foundation and Cambridge, Mass.: MIT Press, 1983), 93.

31 Donald L. Hoffmann, “Pioneer Caisson Building Foundations: 1890,” Journal of the Society of Architectural Historians, 25, no. 1 (March 1966): 68–71.

32 Longstreth, On the Edge of the World, 299–301.33 Reyner Banham, Age of the Masters: A Personal

View of Modern Architecture (New York: Harper & Row, 1962), 157.

34 Gropius, The New Architecture and the Bauhaus, 19–24.

35 Curtis, Modern Architecture Since 1900, 196.

Endnotes

1 Colin Rowe, “Chicago Frame,” irst published in Architectural Review, November 1956, 285–89. Reprinted in Colin Rowe, The Mathematics of the Ideal Villa and Other Essays (Cambridge, Mass.: MIT Press, 1976), 285–289.

2 Carl W. Condit, The Chicago School of Architec-ture: A History of Commercial and Public Building in the Chicago Area, 1875–1925 (Chicago: University of Chicago Press, 1964), 79.

3 Louis H. Sullivan, The Autobiography of an Idea (New York: Dover Publications, 1956), 308; and Kenneth Frampton, Modern Architecture: A Critical History (London: Thames & Hudson, 1992), 21.

4 The irst hydraulic elevator in Chicago was installed in 1870 at the Burley and Company Building on West Lake Street. See Condit, The Chicago School of Architecture, 21. In 1899, the critic Montgomery Schuyler claimed that “the elevator doubled the height of the ofice building and the steel frame doubled it again,” as quoted in Frampton, Modern Architecture, 52.

5 Although originally coined by the architect Thomas Tallmadge in 1908 to signify a group of residential designers that included Frank Lloyd Wright, the term Chicago School has since been expanded to include the commercial architects of the 1880s and 1890s.

6 Sigfried Giedion, Space, Time and Architecture: The Growth of a New Tradition (Cambridge, Mass.: Harvard University Press, 1967), 208.

7 A. N. Rebori, “The Work of Burnham and Root,” Architectural Record, July 1915, 41.

8 Kristen Schaffer, Daniel H. Burnham: Visionary Architect and Planner, ed. Scott J. Tilden (New York: Rizzoli, 2003), 10.

9 Condit, The Chicago School of Architecture, 67.10 William Dudley Hunt, The Contemporary

Curtain Wall (New York: F. W. Dodge Corp., 1958), v.

11 Charles E. Jenkins, “A White Enameled Building,” Architectural Record, January–March 1895, 299.

12 Condit, The Chicago School of Architecture, 111. Similarly, Giedion calls the Reliance Building “an architectonic anticipation of the future” and suggests that it was an inspiration for Mies van der Rohe’s visionary skyscraper projects of the 1920s. See Giedion, Space, Time and Architec-ture, 388. The so-called dematerialization of the curtain wall is the subject of interesting debate in Joanna Merwood, “The Mechanization of Cladding: The Reliance Building and Narratives of Modern Architecture,” Grey Room (Summer 2001): 52–69.

13 Jay Pridmore, The Reliance Building: A Building Book from the Chicago Architecture Foundation (San Francisco: Pomegranate, 2003), 6.

14 Rowe calls the World’s Columbian Exposition the “debacle which overwhelmed these Chicago architects” and “cut short their development.” See Rowe, “Chicago Frame,” 286. Interestingly, when this essay was reprinted in The Mathematics of the Ideal Villa and Other Essays, Rowe inserted a qualiier that was not present in the original version: the exposition was now an “alleged debacle.”

15 The Crystal Palace, a grand exhibition hall, was essentially an immense iron-framed shed clad on all sides in glass. It is often held to be an inluence on later curtain wall development, although this


2

Visions of a Transparent Future

2.1

25Visions of a Transparent Future

topic related to glass architecture, from the psychological effects of colored glass to the notion of lighting a space via translucent loors. Perhaps most notable, however, is Scheerbart’s dramatic depiction of an entire world of glass architecture, evident here in a passage that seems to acknowledge the ongoing rise of the frame structure:

The face of the earth would be much altered

if brick architecture were ousted everywhere

by glass architecture. It would be as if the

earth were adorned with sparkling jewels

and enamels. Such glory is unimaginable. . . .

We should then have a paradise on earth,

and no need to watch in longing expectation

for the paradise in heaven.4

Furthermore, Scheerbart articulated his faith in the possibility that this new glass architecture would impact society on a fundamental level:

We live for the most part in closed rooms.

These form the environment from which

our culture grows. Our culture is to a certain

extent the product of our architecture. If we

want our culture to rise to a higher level, we

are obliged, for better or for worse, to change

our architecture. . . . We can only do that

by introducing glass architecture, which

lets in the light of the sun, the moon, and the

stars, not merely through a few windows,

but through every possible wall, which will

be made entirely of glass—of colored glass.

The new environment, which we thus create,

must bring us a new culture.5

With his lyrical, effusive rhetoric, Scheerbart found an American counterpart in Frank Lloyd Wright. For Wright, glass represented the potential liberation of inte-rior space, the reintegration of the interior with its exterior setting. A transparent envelope would permit a building to merge organically with the landscape. For its abil-ity to aid in this pursuit, Wright referred to glass as a “super-material,” nothing less than a miracle.6 Echoing Scheerbart, Korn, and Mies, Wright wrote, “Walls themselves because of glass will become windows, and windows as we used to know them as holes in walls will be seen no more.”7 And like Scheerbart, Wright also wrote of an imag-ined future world constructed of glass:

The contribution of the present age

is that it is now possible to have an inde-

pendent wall of glass, a skin of glass

around a building; no longer a solid wall

with windows. Even though the window

might be the dominant part—this window

is the wall itself, or in other words, this

wall is itself the window. And with this we

have come to a turning point. . . it is the

disappearance of the outside wall.1

This quote, from Arthur Korn’s 1929 book Glass in Modern Architecture, typiies the profession’s growing fascination with the potential dematerialization of the building envelope made possible by the new struc-tural frame and its corollary, the curtain wall. This interest centered on the concept of transparency and the increased use of glass, which was quickly becoming the primary component of the new building envelope. It is therefore important to examine two develop-ing trajectories of the early twentieth century: theories of glass architecture and technolo-gies of glass production.

In the early decades of the twentieth century, one of the envisioned promises of modern architecture was a future in which the concept of transparency—in both its literal and phenomenal manifestations2—would have a liberating effect, leading to new and improved modes of cultural expression. Concepts of transparency and luminosity were often equated with enlightenment and considered a bellwether of modern culture, especially in Europe, where architects such as Bruno Taut, Ludwig Mies van der Rohe, and Walter Gropius, among others, led a design movement based on these ideals, which, for them, represented the future of architecture. Although these architects are rightly consid-ered to be among the fathers of modernism, there is another, lesser-known igure whose work was highly inluential in this period. Paul Scheerbart was a Berlin-based poet and novelist whom the historian Reyner Banham has referred to as one of modernism’s “missing pioneers”3 due to his importance and relative obscurity. In his book, Glasarchitektur, which was published in Berlin in 1914, Scheerbart describes an imagined future world in which glass becomes the dominant material of architecture. This unusual book is comprised of 111 short chapters—some no more than a sentence long—each addressing a speciic

2.1

Maison Domino,

perspective drawing,

Le Corbusier, 1914


input from the engineer Max Du Bois, and it seems to point toward Le Corbusier’s development of the free plan and free facade concepts, while simultaneously referencing the earlier concrete work of his former employer, Auguste Perret, and that of François Hennebique. Although Le Corbusier did not explicitly explore the curtain wall in his earliest deployments of the Domino hous-ing system (opting instead for an inill of solid masonry with strip windows), his famous drawing stands as a clear polemic. It was a provocation to architecture, freeing not only the plan but also the elevation, and calling into question the status of the wall, which could now become almost anything, limited only by the architect’s imagination.

A few years later, Mies produced plans for two visionary projects for prototypical glass skyscrapers—a faceted, prismatic design in 1921 and a curvilinear construction in 1922, both sited in Berlin. [2.2 + 2.3] Although unbuilt, both projects were designed to employ frame structures, the irst in steel and the second in reinforced concrete, and both were to be fully encased in all-glass curtain walls. Frampton has written that Mies’s 1921 skyscraper proj-ect was a direct response to Scheerbart’s Glasarchitektur.10 Mies himself, writing in Taut’s magazine Fruhlicht in 1922, described the relationship of skin to structure in his skyscraper projects as follows:

Instead of trying to solve new problems

with old forms, we should develop the

new forms from the very nature of the new

problems. We can see the new structural

principles most clearly when we use glass

in place of the outer walls, which is feasible

today since in a skeleton building these

outer walls do not actually carry weight.

The use of glass imposes new solutions.11

Mies’s projects are remarkable for their startling proposed use of an all-glass curtain wall on such immense scales (twenty and thirty stories, respectively) as well as for their prescience. Though lacking in detail, the suggestion of a fully transparent loor-to-loor glass enclosure on tall buildings indicated a new direction for the curtain wall. Mies was not interested in merely a simple or literal transparency; he developed a design process using actual glass models to determine the building form, thereby

Imagine a city iridescent by day, luminous

by night, imperishable! Buildings, shimmer-

ing fabrics, woven of rich glass; glass all

clear or part opaque and part clear, pat-

terned in color or stamped to harmonize

with the metal tracery that is to hold it

all together. . . .We have yet to give glass

proper architectural recognition.8

An obsession with the idea of novelty was a driving force in the work of some architects and writers, who, like Scheerbart, advocated new ways of thinking about architecture and designing buildings, which, the poet argued, would result in an elevation of culture. He was writing at a time when architects were just beginning to rethink the form, substance, and performance of the building envelope. Although Scheerbart died just one year after publishing Glasarchitektur, his continued inluence can be seen in the work of a num-ber of early modern architects, including three mentioned earlier—Taut, Mies, and Gropius. We have already seen evidence of such an inluence in the design of the Bauhaus Building by Gropius and Meyer; in a 1919 letter to a col-league, Gropius wrote, “You absolutely must read Paul Scheerbarth [sic]. In [his] works you will ind much wisdom and beauty.”9

At the same time that Scheerbart was writing in Berlin, the architect Charles-Édouard Jeanneret (soon to take the pseud-onym Le Corbusier) was developing his 1914 proposal, Maison Domino, represented in an iconic and somewhat abstract perspec-tive drawing showing a two-story structure of reinforced-concrete columns and lat slabs, minus any indication of enclosure. [2.1] At irst glance, it would appear that the “disappearance of the outside wall” that Korn postulated had been fully achieved. But Le Corbusier’s drawing was not a depic-tion of a inished building; rather, it was an illustration of a proposed system for con-structing economical mass-produced hous-ing, which he envisioned as a solution for the coming reconstruction of France after World War I. The project’s title was appar-ently derived from the words domicile (or domus) and innovation; some have also sug-gested a double meaning, with the observa-tion that when multiple units were arranged in rows or L-shaped plans, they resembled dominos. The frame structure, with its cantilevered loor slabs, was designed with

2.2

Glass Skyscraper

Project, perspective

drawing, Mies van der

Rohe, 1921

2.3

Glass Skyscraper

Project, photograph of

model, Mies van der

Rohe, 1922


working to achieve a desirable play of relec-tions on the facade.12 Even in this early work, he displays knowledge of the full expressive range of glass, from transparency to relec-tivity and even opacity. The irst image one encounters in Korn’s Glass in Modern

Architecture is a photograph of Mies’s sky-scraper model, as if to suggest that it was the genesis for all that followed. Although these projects by Mies were never realized— the technology did not yet exist to solve the technical requirements of such a curtain wall—the all-glass skyscraper has been a running theme in every subsequent phase of modern architecture. Several decades later, Mies himself would inally have the opportunity to explore these ideas in built form in his highly inluential towers in Chicago, New York, and elsewhere.

Though Scheerbart’s Glasarchitektur remained untranslated until 1972, the rele-vance and inluence of the book’s ideas should not be underestimated. Nearly seven decades after its initial publication, Banham wrote of Glasarchitektur that “of all the visionary writings of that period, this book has the greatest impact nowadays as the concrete and tangible vision of the future environment of man.” 13 What impressed Banham—and what remains impressive today—is Scheerbart’s attention to not only a poetic vision of glass architecture but also his farsighted concern for technical solu-tions to glass architecture’s potential inad-equacies. This is all the more impressive considering that he was primarily a poet, not an architect or engineer.

Many of the practical issues Scheerbart touched on in 1914 continue to be the focus of much research today. For instance, he identiied the importance of the double wall, writing that “since air is one of the worst con-ductors of heat, all glass architecture needs the double wall.”14 This is a remarkably insightful idea that illustrates his solid grasp of the technical issues related to glass build-ings. It foreshadows the development of double-pane insulating glass in the late 1930s as well as the functional, active double-skin curtain wall systems that were not fully devel-oped until the 1980s and 1990s. Scheerbart explains that the insulating cavity between the two glass walls can be utilized for lighting, writing that “with this type of lighting the whole glass house becomes a big lantern.”15

2.2

2.3


The next major breakthrough was the development of tempered glass in the late 1920s. Still in use today, tempering is a sec-ondary process that improves strength char-acteristics, regardless of the process by which the glass is produced. Also known as toughened glass, tempered glass is made by heating the sheet in a furnace until it begins to soften, at about 1,200°F, then cool-ing it quickly by blowing air simultaneously on both sides.20 This process induces com-pression in the outer surfaces, resulting in improved performance under lateral load-ing. Tempered glass is characterized by its increased strength and the unique way in which it fractures when broken. It is up to four times stronger than regular, nontem-pered glass (also called annealed glass), and when broken, it shatters into relatively safe, small pieces with dull edges. The inven-tion of tempered glass provided a more durable and safer product that would further encourage the use of larger expanses of glazing in architecture.

The Libbey-Owens-Ford Company was a major producer and innovator among United States manufacturers in the early- and mid-twentieth century. It was one of the irst companies to develop a prefabricated double-pane insulating glass unit, called Thermopane, which appeared in its catalog in 1940. The product addressed one of the major drawbacks of single-pane windows: their poor insulating value. By creating a sealed airspace between two panes of glass separated by a metal spacer, Thermopane and other similar products, such as Pittsburgh Plate Glass’s Twindow, signiicantly improved the U-value. After further improvements to the materials and methods of spacing and sealing, double- and triple-pane insulating units were in wide use, and their prevalence continues in architecture today.

In the 1950s, Sir Alistair Pilkington, work-ing in England, invented a new method of architectural glass production—called the loat

process—that still dominates the industry and that fed the rapid growth of glass archi-tecture during the second half of the twentieth century.21 Pilkington melts the raw materials and then “loats” the mixture onto a bed of molten tin, the surface of which is almost per-fectly lat—thus forming an almost perfectly even surface on both the tin and air sides of the sheet, free of the distortions and waves

He understood that heating and cooling ele-ments should not be placed in the space between walls, as too much warmth or cold would be lost to the outside atmosphere.16 He also recognized that glass architecture is appropriate only in certain climates, namely, in temperate zones and not in tropical or polar regions.17 He had an intuitive under-standing of the importance of factors such as climate, energy, and industrial production for the success of the new glass architecture. At the time, the glass industry did not have many solutions to these problems; there would, however, eventually be a number of new inventions and other developments to address such concerns.

In its basic form, glass is a mixture of sand, soda, and limestone, heated until molten (about 2,400°F) and then slowly cooled to a solid.18 Humans have produced it for thou-sands of years in various forms; with gradual reinements and developments, it has become a nearly ubiquitous material in architecture, industry, and art. The type of glass eventu-ally developed for use as windows in building construction is known as architectural glass (as opposed to art glass, automotive glass, or other forms). Since it is typically required in relatively large, lat sheets of various thicknesses and with speciic strength and optical qualities, it has its own unique man-ufacturing and processing requirements. Scheerbart’s 1914 treatise urged a revolution in glass architecture shortly after a signii-cant transformation had already occurred in the architectural glass industry. In 1904, the process of drawn glass was patented in Belgium; a similar process was patented in the United States the following year. This technique involved drawing a sheet of mol-ten glass from a vat, at a rate of up to 120 feet per hour; the sheet was then passed through a series of rollers until cooled. This ribbon of glass could be continuously produced as long as the raw materials were supplied to the melting furnace. In its mechanization, this technique represented a distinct advan-tage over existing methods, in which single pieces of lat glass were produced through blowing or casting. The invention of the drawn-glass process represented the irst signiicant innovation in lat-glass produc-tion in 250 years, and without it, the trans-parent dreams of early modernism may never have come to fruition.19


air) and periodic advances in available tech-nology, this idea found expression in the rapidly growing use of glass in the building envelope. In a broader sense, the concept of transparency in architecture was further embraced as symbol and catalyst for a new, open society. In retrospect, the relative success of this latter agenda has been widely critiqued, as Annette Fierro wrote, “Prophesies of societal reformation were at best naïve, hopelessly confused between the literal prop-erties of architecture and its associated meta-phors.”24 The magical “disappearance of the outside wall” that Korn described in 1929 certainly captures the spirit of the era but would prove, in reality, to be a myth. Further development and dissemination of the glass curtain wall in the mid-twentieth century would require more—not less—attention to the tectonics of materials and their assembly.

Endnotes

1 Arthur Korn, Glass in Modern Architecture (London: Barrie & Rockcliff, 1968), 6. First published in German as Glas im Bau und als Gebrauchsgegenstand in 1929.

2 In their seminal essay on transparency, Colin Rowe and Robert Slutzky make an important distinction between the literal and the phenom-enal: “Transparency may be an inherent quality of a substance—as in wire mesh or glass curtain wall, or it may be an inherent quality of organization.” Colin Rowe and Robert Slutzky, “Transparency: Literal and Phenomenal,” Perspecta 8 (1963): 45–54. Reprinted in Rowe, The Mathematics of the Ideal Villa and Other Essays, 159–76.

3 Reyner Banham, “The Glass Paradise,” Architectural Review, February 1959, 89.

4 Paul Scheerbart and Bruno Taut, Glass Architecture and Alpine Architecture, ed. Dennis Sharp, trans. James Palmes and Shirley Palmer (New York: Praeger, 1972), 46. This volume contains English translations of Scheerbart’s Glasarchitektur (1914) and Taut’s Alpine Architektur (1919). All quotations are from Glass Architecture and Alpine Architecture.

5 Scheerbart and Taut, Glass Architecture and Alpine Architecture, 41.

6 Frank Lloyd Wright, The Natural House (New York: Horizon Press, 1954), 51.

7 Ibid., 53.8 Frank Lloyd Wright, “In the Cause of Architecture,”

Architectural Record, July 1928, 11–16. A compari-son of Wright and Scheerbart is also made in Frampton, Modern Architecture, 187.

9 As quoted in John Stuart, The Gray Cloth: Paul Scheerbart’s Novel on Glass Architecture, trans. John Stuart (Cambridge, Mass.: MIT Press, 2001), xiii.

10 Frampton, Modern Architecture,162. See also Banham, “The Glass Paradise,” 89, where he writes that Scheerbart “spoke of America as the country where the destinies of glass architecture would be fulilled, and spoke of the propriety of the ‘Patina of bronze’ as a surface. In other words, he stood closer to the Seagram Building than Mies did in 1914.”

11 Ludwig Mies van der Rohe, Fruhlicht (1922), as translated in Peter Carter, Mies van der Rohe at Work (London: Phaidon Press, 1999), 18.

12 Frampton, Modern Architecture, 162.13 Reyner Banham, The Architecture of the

Well-tempered Environment (Chicago: University of Chicago Press, 1969), 125.


15 Ibid., 51.16 Discussion of Le Corbusier’s “neutralizing wall”

in Banham, The Architecture of the Well-tempered Environment, 156–63.


18 Joseph Amstock, Handbook of Glass in Construction (New York: McGraw-Hill, 1997), 11.

19 Michael Wigginton, Glass in Architecture (London: Phaidon Press, 1996), 55; and Amstock, Handbook of Glass in Construction, 16.

20 Wigginton, Glass in Architecture, 55.21 Ibid., 64.22 Amstock, Handbook of Glass in Construction, 4.23 Ibid., 52.24 Annette Fierro, The Glass State: The Technology

of the Spectacle, Paris 1981–1998 (Cambridge, Mass.: MIT Press, 2003), 39.

inherent in earlier manufacturing techniques. After partial cooling (to make the glass some-what rigid), the continuous strip is transferred onto a conveyor of rollers, where it is gradually cooled and eventually cut into pieces. There is no further polishing or grinding required for either surface—a major improvement over previous production methods. Fully auto-mated loat lines now run constantly, twenty-four hours per day, seven days per week.22 Today, there are more than seventy-ive loat plants operating in the world, producing more than 90 percent of the architectural glass manufactured in the Western world.23

In the buildings and texts of the early- and mid-twentieth century, the modernist ideal of transparency was, in fact, evident both metaphorically and literally. Coupled with the growing importance of views and natural light (and, to a lesser extent, fresh


3

The Mid- Twentieth-Century Curtain Wall

3.1

United Nations

Secretariat, New York,

New York,

Wallace K. Harrison

(director of planning),

1950

3.2

United Nations

Secretariat, typical

floor plan

3.3

Advertisement describ-

ing the Secretariat as

the “World’s Largest

Window,” originally pub-

lished in Architectural

Forum, 1950

3.4

United Nations

Secretariat, typical mul-

lion plan detail

3.5

United Nations

Secretariat, wall section

3.1 3.2

31The Mid-Twentieth-Century Curtain Wall

are composed of glass curtain walls designed to maximize daylight and views, while the narrow north and south elevations, clad entirely in Vermont marble, are windowless. The curtain wall is suspended two feet and nine inches (80 centimeters) beyond the perimeter column line and consists of alu-minum mullions on four-foot (1.2 meter) centers, spanning loor to loor, into which are inserted 5,400 double-hung aluminum windows and the same number of glass spandrels. [3.3] Blue-green-tinted, heat-absorbing glass is used throughout; at the spandrels, wired glass is used in front of a low masonry wall that is painted black on its outer surface. [3.4 + 3.5]

The inal coniguration of the Secretariat curtain wall was the subject of signiicant debate and controversy. During the design team’s deliberations, Le Corbusier had been adamant that the east and west facades should incorporate a system of exterior brise- soleil to protect the glass from excessive sunlight. He had successfully employed the system in previous projects, two of which are discussed in greater detail below. Before con-struction began, Le Corbusier felt compelled to take his argument to the chair of the UN Headquarters Advisory Committee, writing in a iery letter: “My strong belief is that it is senseless to build in New York, where the climate is terrible in summer, large areas of glass which are not equipped with a ‘brise-soleil.’ I say this is dangerous, very seriously dangerous.”4 His warnings were not heeded. Harrison and the UN Planning Ofice dis-missed the proposal, presenting counterar-guments that the exterior sunshades would

In a 1966 review of Mies van der Rohe’s work, the critic Ada Louise Huxtable called the “glass box,” as derived from Mies’s inno-vations, “the genuine vernacular of the mid-twentieth century.” 1 Acknowledging its deiciencies in the hands of less-skilled architects, she nevertheless saw this build-ing type as a legitimate and occasionally brilliant response to the needs of modern commercial society in the postwar era. Though overly simplistic, the term glass box came to signify an architecture character-ized by simple volumetric forms comprised of frame structures enclosed primarily with glass curtain walls. From the late 1940s through the 1960s, this paradigm was methodically explored in diverse building types, on a wide range of scales and in vari-ous cities around the world, but it found its most inluential expression in three ofice buildings constructed in New York City in the 1950s: the United Nations Secretariat,

Lever House, and the Seagram Building.2 The thirty-nine-story Secretariat (1950)

is the largest and most visible component of the United Nations Headquarters, which also includes the General Assembly (1952), the Conference and Visitors Center (1952), and the Dag Hammarskjöld Library (1961).3 Wallace K. Harrison was the director of planning for the complex, leading an inter-national team of architects that included Le Corbusier and Oscar Niemeyer. [3.1 + 3.2] The Secretariat is sited with its long axis parallel to the East River. The skin of this steel-framed tower establishes a clear dichotomy of solid and void. The two wide elevations—facing roughly east and west—

3.4

3.5

3.3


a new era of high-rise glass architecture. In the November 1950 issue of Architectural

Forum, the magazine’s editors concluded, “Just as the modern Secretariat had supplied a monumental symbol for the UN, so the UN had, in turn, given modern architecture an aura of respectability, an association with world-wide prestige.”10 After decades of deferred maintenance, the entire United Nations complex, including the Secretariat curtain wall, is slated for a major $1.9 billion renovation project beginning in 2008.11

It is perhaps understandable that Le Corbusier was so spirited in his advocacy for brise-soleil at the United Nations— he had learned this lesson the hard way. His Cité de Refuge (1933), the Salvation Army’s hostel and rehabilitation center in Paris, fea-tured a multistory, hermetically sealed, south- facing curtain wall of single-pane glass. In the heat of summer, this wall created an intoler-able greenhouse effect for the rooms within. Thirteen months after the building opened, local planning authorities demanded that operable windows be installed; eventually, the south facade was retroitted with exterior brise-soleil, in the form of projecting vertical and horizontal ins, to mitigate the solar issues.12 To his credit, Le Corbusier had origi-nally envisioned a much more sophisticated enclosure system for the building. His initial design was for a double-skin curtain wall—an example of his mur neutralisant (neutral-izing wall) concept, consisting of two layers of glass separated by an interstitial cavity through which, depending on the season, either cooled or heated air could be circulated, thus creating a buffer zone between interior and exterior environments. This enclosure was to be coupled with an advanced central air-conditioning system (quite new and uncommon in France at the time) to main-tain comfortable interior conditions.13 For budgetary reasons, the sealed curtain wall was built with just a single pane of glass and the cooling equipment was eliminated altogether (only heating and ventilation were provided), with terrible results.

One of the irst large-scale deployments of Le Corbusier’s brise-soleil concept can be found at the headquarters of the Ministry of Education and Health (1943) in Rio de Janeiro, Brazil. Like the United Nations complex, it was designed by a team of architects, in this case headed by Lucio Costa and Niemeyer.

add signiicant cost to the project, present a future maintenance problem, and become a snow and ice hazard in winter. It was also argued that the east-west orientation would not be as onerous as some imagined because the Manhattan grid is actually skewed twenty- nine degrees from true north. Therefore, they claimed, the west facade would actually face northwest, and the harsh effects of the after-noon sun would be diminished. In the end, an analytical study of various glass types and conigurations—including the construction of a four-story mock-up of the curtain wall—convinced Harrison and his colleagues that blue-green-tinted, heat-absorbing glass would be appropriate, both economically and technically, for the curtain wall.5

Throughout the construction phase and upon completion, the building garnered positive attention from architects as well as the general public. But the critic Lewis Mumford, for one, was unimpressed, calling the Secretariat “not a work of three-dimen-sional architecture, but a Christmas package wrapped in cellophane.”6 In a review of the building for the New Yorker, he observed that during its irst summer in operation, work-ers in the Secretariat found that excessive solar heat gain and glare made it necessary to keep the interior blinds fully drawn most of the day, such that “the result of misorienting the Secretariat and using glass so exuber-antly is to create a building that functionally is often windowless on all four sides.”7 Various corrective measures, including applying relective ilm to the glass, were eventually attempted to remedy the solar heat gain.8 Le Corbusier was vindicated. Mumford also pointed out that when viewed from the street, the green-tinted glass walls were rarely trans-parent, as apparently intended, but often rather dark and relective, essentially acting as enormous mirrors to relect the sky and urban context. Mumford did, however grudgingly, acknowledge the mesmerizing and “incomparable” aesthetic effects of the great glass wall from the exterior: “No build-ing in the city is more responsive to the con-stant play of light and shadow in the world beyond it; none varies more subtly with the time of day.”9 Though clearly lawed in exe-cution, the Secretariat represented a major step forward in the development of the cur-tain wall, giving it a forceful presence in a prominent building and helping to usher in


Le Corbusier served as a kind of senior con-sultant and mentor to the team. The design is also notable as a large-scale implementa-tion of his “Five Points of a New Architecture.” These included pilotis to raise the mass of the building off the ground, the roof garden, the free plan, the free facade, and the horizon-tal ribbon window. The ministry building, which has been called the origin of modern architecture in Brazil,14 is an obvious precur-sor to the Secretariat building. The elongated, rectangular tower contains two broad, trans-parent facades framed by two solid end walls. On the sunless southern side, the building is enclosed with a curtain wall of loor-to-ceiling glass, incorporating double-hung windows for ventilation. This system is repeated on the sunny northern side but with the addition of exterior brise-soleil featuring deep vertical ins supporting adjustable, horizontal cement- panel louvers. [3.6 + 3.7] This design is intriguing not only for its practical problem-solving but also for its recognition that a build-ing should respond directly and speciically to its local climate and orientation. As the Ministry of Education and Health building shows, the brise-soleil system can be ine-tuned to a site’s sun angles, maintaining the desired effects of the glass wall while miti-gating its inherent problems. Banham calls the brise-soleil system one of Le Corbusier’s “most masterly inventions.”15 In his later buildings, such as the High Court (1955) in Chandigarh, India, and the Carpenter Center (1964) in Cambridge, Massachusetts, the brise-soleil became the dominant expressive element. Along with his neutralizing double-wall concept, the brise-soleil continues to

3.6

3.7

3.6

Ministry of Education

and Health, Rio de

Janeiro, Brazil, south

elevation, Lucio Costa

and Oscar Niemeyer

(directors of planning),

1943

3.7

Ministry of Education

and Health, north

elevation


3.8

3.9

3.8

Lever House,

New York, New York,

Skidmore, Owings and

Merrill, 1952

3.9

Lever House, typical

tower floor plan

3.10

Lever House, wall

section

3.11

Lever House, typical

mullion plan detail (left)

and window-washing

guide rail (right)


capture the architectural imagination, as can be seen in several of the contemporary case studies described later in this book.

Soon after United Nations employees moved into the Secretariat, construction workers were putting the inishing touches on Lever House (1952) on Park Avenue in New York City. [3.8 + 3.9] This twenty-one-story steel-framed tower was designed by Gordon Bunshaft of Skidmore, Owings and Merrill (SOM). Lever House was the irm’s irst high-rise ofice building, and it established the irm as a leader in this building type, which it would go on to develop in cities throughout the world. An immediate draw for curious visitors who lined up to tour the building,16 Lever House was also well received by the architectural press, as noted in a 1952 article in Architectural Forum describing it as “ininitely more spirited and digniied than any other commercial ofice building in New York.”17 It is perhaps dificult today to imagine the impact this new type of glass skyscraper would have had at the time, with its characteristic lightness and transparency set against the traditional heavy masonry buildings of Park Avenue. Similar to the Secretariat, the Lever House curtain wall consists of a continuous skin of glass framed in metal, including wire glass span-drels to mask the underlying masonry, as required by building code for ire safety. [3.10] The primary glass type is a single pane of blue-green-tinted, heat-absorbing glass—it was claimed at the time to block 45 percent of the sun’s heat—which is held by steel-channel mullions clad inside and out with sixteen-gauge stainless steel. [3.11]

Transparent vision glass constitutes just over 50 percent of the wall. The Lever House contrasts with the Secretariat in several important ways. The glass in Lever House is ixed in place, without operable windows, relying entirely on air-conditioning for inte-rior comfort (ixed glass reportedly cost 30 percent less than operable windows).18 Lever House is also the irst built example of the curtain wall expressed as an uninter-rupted glass membrane, stretching around the tower’s corners to cover all elevations equally. The continuous glazing and narrow loor plate ensured that no desk was more than twenty-ive feet from a window. Although not plagued by solar-heat-gain issues to the same degree as the Secretariat, interior blinds in the building were often drawn to control glare within the ofice spaces. Another unique feature was its innovative window-washing system: A motor-driven gondola carrying two workmen, who were employed full-time for this purpose, was suspended from a crane that moved on tracks along the perimeter of the roof. 19 The gondola was guided on its vertical ascent and descent by steel rails projecting from and integrated within the mullions, corresponding to the centerlines of the structural columns. This elaborate and necessary system—the irst of its kind—points to the importance of maintaining the clean, smooth surface of glass, not only for a soap company like Lever Brothers but also for modern archi-tecture’s image in general.20

Lever House would soon be accompa-nied, diagonally across Park Avenue, by the thirty-nine-story Seagram Building (1958),

3.11

3.10


designed by Mies van der Rohe in collabora-tion with Philip Johnson and the irm Kahn and Jacobs.21 [3.12 + 3.13] The steel-framed Seagram Building was the irst major ofice building designed by Mies (he was seventy-two years old at the time), and it was the fullest expression to date of the ideas he irst explored in the 1920s. Notable for its pure massing, with no set-backs, and the creation of a public plaza at the street edge, the building brought a new aesthetic to the ofice building type, one that would be taken up with great fervor by archi-tects, including SOM, in the years that fol-lowed. In contrast to the blue-green coolness of Lever House, the Seagram Building is characterized by a darker, warmer tone, result-ing from a continuous curtain wall of bronze-tinted glass with bronze spandrel panels and projecting mullions installed outside of the building structure. [3.14] Unlike Lever House and the Secretariat, the Seagram Building’s curtain wall contains glass panels that extend unbroken from loor to ceiling. The glass is supported by custom-extruded, vertical mullions suspended off the loor slabs by steel angles. These I-shaped mul-lions provide the structural component of the curtain wall, spanning loor to loor, and are placed on the exterior side of the glass, as opposed to the interior, as was the case at Lever House and the Secretariat. [3.15] As the contemporary Spanish architects Iñaki Ábalos and Juan Herreros have noted, the exterior positioning of the mullion gave the facade some depth and a machinelike appear-ance but provided no technological advantage.22 In fact, this positioning was problematic in

3.12

3.13

3.12

Seagram Building,

New York, New York,

Mies van der Rohe in

collaboration with Philip

Johnson and Kahn and

Jacobs, 1958

3.13

Seagram Building, typi-

cal tower floor plan


that it exposed the mullion to weathering and to thermal expansion and contraction. The Seagram Building’s curtain wall system begins at the ceiling of the lobby, giving the impression of a loating mass while expos-ing the structural columns at ground level. Mumford found Mies’s curtain wall to be a wholly suitable solution: The faces of the building, instead of being an

expression of the structure, are frankly and

boldly a mask, designed to give pleasure to

the eye and to complement, rather than to

reveal, the coarser structure form behind it.

This is, after all, a logical treatment of the

curtain wall, for the very nature of a cur-

tain is to be detached from the structure,

not to support it.23 [3.16]

Although the Seagram Building was Mies’s largest curtain wall project to date, it was certainly not his irst. In the years leading up to it, he had completed a series of high-rise residential buildings that clearly illustrate the evolution of his curtain wall design, particularly with respect to the relative positioning of structure and cladding. The earliest of these, built on Chicago’s South Side, was the Promontory Apartments (1949), in which the reinforced-concrete frame is clearly exposed and expressed, with an inill of masonry spandrels and recessed steel-framed windows. [3.17 + 3.18] For the same client, developer Herbert Greenwald, Mies then designed 860–880 Lake Shore Drive (1951) on the North Side. Consisting of two twenty-six-story towers set at right angles and derived from an earlier design for the Promontory

3.14

3.15

3.16

3.14

Seagram Building,

under construction

3.15

Seagram Building,

typical mullion plan

detail

3.16

Seagram Building

corner


3.17 3.18

3.19 3.20

3.17

Promontory

Apartments, Chicago,

Illinois, Mies van der

Rohe, 1949

3.18

Promontory Apartments,

wall section

3.19

860–880 Lake Shore

Drive, Chicago, Illinois,

Mies van der Rohe,

1951

3.20

860–880 Lake Shore

Drive, wall section

3.21

900 Esplanade,

Chicago, Illinois, Mies

van der Rohe, 1956

3.22

900 Esplanade, wall sec-

tion

3.23

Seagram Building, wall

section, Mies van der

Rohe in collaboration

with Philip Johnson and

Kahn and Jacobs, 1958

3.24

Inland Steel Building,

Chicago, Illinois,


Merrill, 1958


Apartments, this project is considered a milestone in Mies’s work. It was at this point that he irst developed the vocabulary of skyscraper curtain walls that would occupy much of his remaining career and would inluence countless others. [3.19 + 3.20] The glass is still positioned within the struc-tural frame but is now lush with its outer surface. Black-painted steel plates, in the same plane as the glass, cover the edge beams and columns. The glass is held in place using anodized-aluminum glazing frames, incorporating operable hopper windows, which are in turn supported by projecting mullions of black-painted rolled-steel I-sections. The welded-steel curtain wall frames were fabricated in units, two stories high by 21 feet (6.4 meters) wide, and then hoisted into place.24 One block to the north, Greenwald commissioned another pair of apartment buildings from Mies for 900 Esplanade (1956). In these towers, the curtain wall fully encases the reinforced-concrete lat-slab structure; the glass plane is set twelve inches beyond the outer sur-face of the structural column. Mies’s trade-mark projecting mullions are present but are now formed of extruded aluminum, thus reducing the dichotomy of steel mul-lion and aluminum glazing frame found in the previous project. [3.21 + 3.22] In contrast to the clear glass at 860–880 Lake Shore Drive, a newly developed gray-tinted, heat-absorbing glass appears to merge with its black aluminum framing, giving the facades an abstract uniformity. Due to the elimina-tion of perimeter beams and ceiling cavities, the spandrel is reduced to a minimal expres-

sion of slab thickness, thereby maximizing the proportion of glass. As Phyllis Lambert writes, “900 Esplanade was the experiment that Mies would elaborate and reine in the Seagram Building, which became the iconic embodiment of the Miesian tall building.”25 Indeed, the Seagram Building section reveals that the curtain wall is now completely free of the structure, passing uninterrupted outside the edge of the frame. [3.23]

The Secretariat, Lever House, and the Seagram Building were soon followed by other high-rise buildings that further explored the curtain wall concept and its relationship to structure. At the Inland Steel Building (1958) in Chicago, SOM adheres to the Miesian strategy of an exterior expres-sion of structure—not only for the curtain wall mullions, but also for the building structure. By relegating elevators and other services to a separate tower and inverting the structural columns to the outside of the curtain wall, they were able to create unob-structed ofice loors. The curtain wall itself incorporates stainless steel for the mullion cladding, spandrel panels, and column cov-ers. [3.24] The Inland Steel Building was the irst fully air-conditioned high-rise in Chicago and the irst to use double-pane insulating glass.26 The Corning Glass Works Building (1959) in New York City was designed by Wallace K. Harrison, the chief architect of the Secretariat, and represents a major advancement in the coniguration of the mullion. [3.25] Rather than an assem-bly of disparate parts clad in a inish mate-rial like stainless steel, the mullions at the Corning building consist solely of extruded-

3.21 3.24

3.22

3.23


aluminum sections shaped to interlock. Neoprene gaskets are used to seal joints. The functions of curtain wall substructure, glazing frame, and inished surface are fully integrated. [3.26] This type of dynamic (or split) mullion is still common today, though more attention is now paid to thermal bridging issues.

Low- and mid-rise ofice buildings were also sites for curtain wall experimentation. Notable examples include two New York proj-ects by SOM: the four-story Manufacturers Hanover Trust (MHT) Building (1954) and the eleven-story Pepsi-Cola Building (1960). [3.27] Highly unusual for a bank building at the time, the MHT Building incorporates extensive use of clear glass. It did not suffer from signiicant overheating, however, due to nearly constant shade provided by the taller surrounding buildings.27 The bank’s 1,000-ton safe deposit vault is located just ten feet behind the curtain wall at ground level, fully on display for passersby. The Pepsi-Cola

Building incorporates the largest polished plate-glass panels available at the time—1/2-inch (1.27-centimeter) thick, measuring 9 by 13 feet (2.7 by 4 meters)—set within a delicate frame of silver-anodized extruded-aluminum mullions. [3.28] The vertical mullions follow the Miesian prototype of projecting I-shaped extrusions, but, in this case, the mullion detail reveals that the glaz-ing channel is “hidden” behind the alumi-num I-section and the spandrel plates, resulting in a curtain wall of remarkable transparency and simplicity, and one reduced to its essential elements. [3.29] Another ele-gant incarnation of the midcentury curtain wall is found at the Jespersen Building (1956) in Copenhagen, Denmark, designed by Arne Jacobsen. [3.30] Due to a requirement for automobile trafic to pass under the building at the ground loor, the building mass is raised on two massive columns at the center, from which each loor is cantilevered 18 feet (5.5 meters) on each side. The curtain wall

3.25

3.27

3.26

3.25

Corning Glass Works

Building, New York,

New York, Wallace K.

Harrison, 1959

3.26

Corning Glass Works

Building, typical mullion

plan details

3.27

Manufacturers Hanover

Trust Building, New

York, New York,


Merrill, 1954


is hung off the slab at each loor. [3.31] Though somewhat technologically crude—the mullions are wood faced with aluminum sheets—the curtain wall achieves the reined impression of a loating wall enhanced by the complete lack of any interior structure visible through the glass.28

Although the commercial building was perhaps the curtain wall’s most visible man-ifestation, it was not the only type in which the curtain wall found expression at mid-century. A brief look at some of the institu-tional, educational, and residential buildings that incorporated curtain walls tells a more complete history. Mies himself designed some twenty buildings for teaching, research, and housing on the Chicago campus of the Illinois Institute of Technology (formerly the Armour Institute of Technology), where he had been director since 1938.29 These build-ings—ranging from the Minerals and Metals Research Building (1943) to S. R. Crown Hall (1956)—were low-rise frame structures, and they can be seen in retrospect as a workshop where Mies developed his approach to metal and glass that deined his later work. On the Massachusetts Institute of Technology cam-pus in Cambridge, Eero Saarinen designed the Kresge Auditorium (1955), a 1,200-seat concert hall covered by a distinctive thin-shell concrete dome that touches the ground at three points. [3.32] As the dome rises to a height of ifty feet (15 meters), the space below is enclosed by a minimal steel-framed curtain wall with clear glass that allows the lobby space to function symbolically as an extension of the exterior plaza. [3.33] From outside looking in, the curtain wall appears

3.28

3.29

3.28

Pepsi-Cola Building,

New York, New York,


Merrill, 1960

3.29

Pepsi-Cola Building,

typical mullion plan

detail


3.30

3.31

3.30

Jespersen Building,

Copenhagen, Denmark,

Arne Jacobsen, 1956

3.31

Jespersen Building,

ground-floor plan,

upper-floor plan, and

section


to hang from the edge of the concrete shell; in reality, thin steel columns support it from behind the glass. A steel-framed curtain wall is also used to great effect at Keokuk Senior High School and Community College (1954) in Keokuk, Iowa, designed by Perkins and Will, a irm long known for innovation in school planning. [3.34 + 3.35] A three-story classroom wing is organized with a wide corridor to the south that connects adjacent classrooms and provides expansive views of an amphitheater outside. The corridor is enclosed entirely by a curtain wall of clear glass in steel mullions, with six-inch-deep projecting exterior steel ins and bottom-hinged ventilating sashes dispersed through-out the grid. [3.36 + 3.37] As observed in a 1954 Architectural Forum review, the trans-parency of the curtain wall makes visible the social activities of the school: “At class changes, the whole facade suddenly becomes a fascinating theater of strolling, conversing, criss-crossing adolescents.”30

The concept of the curtain wall as an expansion of the window into an enveloping enclosure system was employed even at the scale of the freestanding single-family resi-dence. Three compact and iconic modern houses, all completed within a two-year period, best demonstrate this phenomenon: the Glass House, the Farnsworth House, and the Eames House. In each, a steel frame provides the structure, while non-load-bearing walls of glass and other lightweight materials pro-vide enclosure. These boxy houses appear almost as individual loors of urban sky-scrapers, pulled out like dresser drawers and deposited on their idyllic sites. Although

3.32

3.34

3.35

3.33

3.32 + 3.33

Kresge Auditorium,

Cambridge, Massachusetts,

Eero Saarinen, 1955

3.34 + 3.35

Keokuk Senior High School

and Community College,

Keokuk, Iowa, Perkins and

Will, 1954


completed irst, Philip Johnson’s Glass House (1949), in New Canaan, Connecticut, was inspired by Mies’s earlier designs for the Farnsworth House (1951), in Plano, Illinois.31 [3.38 + 3.39] Both feature a rectilinear, free plan with an internal service core and a con-tinuous perimeter wall of large plate-glass panels set within a steel frame. There are subtle differences. The Glass House sits directly on a brick base, while the Farnsworth House is elevated off the ground. In the Glass House, the steel frame is painted black, while Farnsworth’s is white. The glass in the Glass House is set at the exterior face of the columns; at Farnsworth, the columns project, with the glass set at their interior faces. In both cases, though, the overriding characteristic is that of literal transparency, achieved through the dis-solution of the traditional wall. The Eames House (1949), in Paciic Palisades, California, illustrates a more eccentric approach in which color, composition, and variation in purpose— rather than literal transparency—are the deining attributes of the facade. Oficially known as Case Study House #8 (commis-sioned by Arts & Architecture magazine), the building was designed by Charles and Ray Eames to demonstrate an artful and innovative use of industrial technology in response to postwar housing needs. Four-inch (0.1-meter) steel H-columns provide the structural framework (erected in just a day and a half), establishing an organizing module within which a grid of panels is set.32 [3.40] The inill panels vary from painted cementitious panels in a range of colors to transparent, translucent, and wired glass. In addition to a personal aesthetic agenda, the arrangement of

these materials within the facade is inluenced by the function of the spaces within, providing varying degrees of transparency or privacy as appropriate. The Eames House established an enduring example of a curtain wall used not merely as a neutral, consistent grid but as a mutable and responsive system of enclosure.

The inluential curtain wall designs of the 1950s, as pioneered by SOM, Mies, and others, were received by the architectural profession and the construction industry as prototypical systems that could be easily manufactured and endlessly repeated (usually with some variation in aesthetic or an occa-sional innovation in technique). Lever House, Banham wrote, was “an uncontrollable suc-cess” that, along with the Seagram Building, would be “imitated to the point of tedium.” 33 Many cities around the world would soon have their own versions of Lever House and the Seagram Building. Along with the curtain wall’s widespread propagation came an inevi-table backlash. An article pointedly titled “The Monotonous Curtain Wall” appeared in Architectural Forum in October 1959, offer-ing the following indictment of the status quo in contemporary architecture:

The standard curtain wall—perhaps

America’s single most important building

innovation in the past decade or so—is

fast becoming, in the hands of less-than-

sensitive architects and manufacturers,

one of the most irritating eyesores on

the U.S. scene.34

Just as Colin Rowe lamented that the frame structure eventually came to represent

3.36

3.37

3.36

Keokuk Senior High

School and Community

College, section,

Keokuk, Iowa, Perkins

and Will, 1954

3.37

Keokuk Senior High

School and Community

College, floor plan


3.38

3.39

3.38

Glass House, New

Canaan, Connecticut,

Philip Johnson, 1949

3.39

Farnsworth House,

Plano, Illinois, Mies van

der Rohe, 1951


“the nakedly irresponsible agent of a too ruthless commercialism,”35 the gridded glass-and-metal curtain wall was soon equated with a menacingly anonymous and ubiqui-tous corporate culture. This critique of the curtain wall was international in scope and even reached into popular culture. See, for instance, the French director Jacques Tati’s 1967 ilm Play Time, in which the protagonist struggles to ind his way through a future version of Paris composed entirely of monot-onous glass skyscrapers, each sporting an identical curtain wall. At one point, a charac-ter visits a travel agency and sees posters advertising various destinations around the world—all of them featuring an image of a skyscraper indistinguishable from those

visible just outside the shop window. Architectural critics were generally correct in pointing out that the main problem was the manner in which architects and builders were unimaginatively deploying the curtain wall, not in the idea of the curtain wall itself as a method of construction. Huxtable wrote in 1966, “The ‘glass box’ is the most maligned building idea of our time,” but “It is also one of the best.”36 In the following decades, archi-tects would seem to engage with the prevail-ing criticism, exploring new vocabularies for the curtain wall beyond the dogma of high modernism and developing new solutions to the inherent, and soon to become highly problematic, environmental inadequacies of the midcentury curtain wall.

3.40

3.40

Eames House, Pacific

Palisades, California,

Charles and Ray Eames,

1949


Endnotes

1 Ada Louise Huxtable, “Mies: Lessons from the Master,” Will They Ever Finish Bruckner

Boulevard? (New York: Macmillan, 1970), 205. First published in the New York Times, February 6, 1966.

2 These three buildings were preceded by Pietro Belluschi’s Equitable Savings and Loan Association Building (1948), a twelve-story ofice building in Portland, Oregon, clad with a lush skin of glass and aluminum panels. The articula-tion of the curtain wall, however, retained a strong expression of the structural grid rather than a continuous skin of glass, which is the innovation of later towers.

3 The United Nations was established in 1945. The design process for the UN Headquarters in New York began in 1947. Groundbreaking took place in 1948, and the original complex was completed in 1952. See Robert A. M. Stern, Thomas Mellins, and David Fishman, “United Nations,” New York

1960: Architecture and Urbanism between the

Second World War and the Bicentennial (New York: Monacelli, 1995), 601–40.

4 As reported in “The Secretariat: A Campanile, a Cliff of Glass, a Great Debate,” Architectural

Forum, November 1950, 108. 5 Stern, Mellins, and Fishman, New York 1960, 613.6 Lewis Mumford, “Magic with Mirrors,” From the

Ground Up: Observations on Contemporary

Architecture, Housing, Highway Building, and

Civic Design (New York: Harcourt Brace, 1956), 37. The essay was originally published in the New Yorker in 1951.

7 Lewis Mumford, “A Disoriented Symbol,” From

the Ground Up, 49. The essay was originally pub-lished in the New Yorker in 1951. Mumford also quotes Henry-Russell Hitchcock saying, “The most signiicant inluence of the Secretariat…will, I imag-ine, be to end the use of glass walls in skyscrapers—certainly in those with western exposures, unless exterior elements are provided to keep the sun off the glass.”

8 See interview with Robert Heintges in “Mr. Glass,” The Architect’s Newspaper, June 20, 2007.

9 Lewis Mumford, “Magic with Mirrors,” From the

Ground Up, 40. 10 “The Secretariat: A Campanile, a Cliff of Glass, a

Great Debate,” Architectural Forum, November 1950, 112.

11 David D’Arcy, “New Scenery for the World’s Stage,” The Architect’s Newspaper, June 25, 2008.

12 Banham, The Architecture of the Well-tempered

Environment, 156–58.13 Kenneth Frampton, Le Corbusier: Architect and

Visionary (London: Thames & Hudson, 2001), 101–3.

14 Elisabetta Andreoli and Adrian Forty, Brazil’s

Modern Architecture (New York: Phaidon Press, 2004), 113.

15 Banham, The Architecture of the Well-tempered

Environment, 158.16 Mumford, “House of Glass,” From the Ground

Up, 156. 17 “Lever House Complete,” Architectural Forum,

June 1952, 104.

18 Jürgen Joedicke, Ofice Buildings (New York: Frederick A. Praeger, 1962), 94. First published in German in 1959.

19 “Lever House, New York: Glass and Steel Walls,” Architectural Record, June 1952, 130–35.

20 Hillary Sample, “Maintenance Architecture,” Praxis, 6 (2004): 106–13.

21 Stern, Mellins, and Fishman, “Seagram Building,” New York 1960, 342–52.

22 Iñaki Ábalos and Juan Herreros, Tower and

Ofice: From Modernist Theory to Contemporary

Practice (Cambridge, Mass.: MIT Press, 2003), 113.23 Lewis Mumford, “The Skyline: The Lesson of the

Master,” the New Yorker, September 13, 1958, 143.24 Carter, Mies van der Rohe at Work, 46.25 Phyllis Lambert, ed., Mies in America (New York:

H.N. Abrams, 2001), 374. Lambert herself was instrumental in convincing her father, Samuel Bronfman, the president of Seagram and Company, to hire Mies for the Seagram Building.

26 Lawrence Okrent, “Inland Steel Building,” AIA Guide to Chicago (Orlando, Fla.: Harcourt, 2004), 67.

27 Stern, Mellins, and Fishman, “Seagram Building,” New York 1960, 374.

28 Joedicke, Ofice Buildings, 192–93.29 Jean-Louis Cohen, Mies van der Rohe (Basel:

Birkhäuser, 2007), 104–9. First published in 1994.30 “Sprawling Campus-Type High School

Contradicts Dogma,” Architectural Forum, October 1954, 112–19.

31 Frampton, Modern Architecture, 240.32 Gloria Koenig, Charles & Ray Eames (Cologne:

Taschen, 2005), 32–9.33 Banham, Age of the Masters, 114–15.34 “The Monotonous Curtain Wall,” Architectural

Forum, October 1959, 142–47.35 Rowe, “Chicago Frame,” as reprinted in The

Mathematics of the Ideal Villa, 108.36 Huxtable, Will They Ever Finish Bruckner

Boulevard?, 205.


4.1

4

New Directions and New Priorities

49New Directions and New Priorities

4.1 + 4.2

Deere and Company

Headquarters, Moline,

Illinois, Eero Saarinen

and Associates, 1964

4.3

Partial wall section

Beginning in the 1960s and continuing to the present day, the approach to the cur-tain wall has been characterized by diverse strategies, due in part to the vicissitudes of architectural fashion at large and to the growing impact of global environmental and economic forces. It seems that each new decade has brought with it a new design doctrine—postmodernism, high-tech, deconstructivism, critical regionalism, green architecture—and the curtain wall concept has been transformed in response. Energy crises in the 1970s and again in the early twenty-irst century, as well as the rise of an environmentalist sensibility, have resulted in widespread and ongoing reeval-uation of architecture in general and a refocusing on the performance of the build-ing envelope. The curtain wall’s endurance through this turbulent period demonstrates that it is indeed a mutable concept, capable of adapting to nearly any design strategy, from minimalist transparency to the histori-cist nostalgia of postmodernism. A study of several buildings from this period will illus-trate how the curtain wall has adapted to various stylistic impulses while also incorpo-rating incremental advances in technology.

At the John Deere & Company Headquarters (1964) in Moline, Illinois, Eero Saarinen and Associates designed a curtain wall that seamlessly melded the Miesian vocabulary of glass and steel with Le Corbusier’s brise-soleil concept, resulting in a strikingly unique and inluen-tial building. [4.1] This complex of three linked buildings—a seven-story administra-tion building, a public exhibition and

auditorium building, and an engineering wing—is nestled into its wooded suburban site, only occasionally emerging into view from the dense surrounding foliage. The exterior of the building is characterized by an external structural skeleton of wide-lange steel members and a system of steel brise-soleil that project forward from a backdrop of gold-tinted relective glass. Saarinen found inspiration in the iron and steel farm machinery manufactured by the John Deere Company, and he translated this inluence into a critique of what he called the “slick, precise, glittering” glass box:

Having decided to use steel, we wanted

to make a building that was really a steel

building (most so-called steel buildings

seem to me to be more glass buildings than

steel buildings, really not one thing or the

other). We sought for an appropriate mate-

rial—economical, maintenance free, bold

in character, dark in color.1

For the steel, Saarinen speciied an alloy known as weathering steel (and by the trade name Cor-ten) that resists corrosion by form-ing a continuous outer coating of iron oxide to protect the steel within. The material thus naturally develops a dark reddish-brown color tone and does not require painting. Saarinen was the irst to use weathering steel, originally used in railroad and bridge construction, in an architectural application. He described the impetus of the curtain wall design as:

Having selected a site because of the

beauty of nature, we were anxious to take

4.2 4.3


full advantage of views from ofices. To

avoid curtains or Venetian blinds, which

would obscure the views, we worked out

a system of sun shading with metal louvers

and also speciied relective glass to pre-

vent glare.2 [4.2]

The gold-tinted relective-coated glass, a relatively new product at the time, reportedly rejected up to 70 percent of heat striking the surface.3 Though mirrorlike by day, relecting the adjacent steel sunshades and tree branches, this glass is fully transparent from the inte-rior; at night, with interior lighting, the glass becomes transparent from the exterior as well. The laminated glass is supported by vertical wide-lange steel mullions, to which it is attached through the use of continuous neoprene glazing gaskets. Together, the relec-tive coating and brise-soleil provide effective protection against solar heat gain and glare at the loor-to-ceiling glass walls. [4.3] Concurrently with the Deere Headquarters, Saarinen’s ofice was planning two other major corporate commissions: IBM’s Thomas J. Watson Research Center (1961) in Yorktown Heights, New York, and Bell Laboratories (1962) in Holmdel, New Jersey. Both are immense, pristine volumes clad primarily in glass. Notable for their sheer size—IBM has a curving gray glass wall measuring 1,000 feet (300 meters) long and Bell Labs is a ive-story relective glass box totaling 700 feet (210 meters) in length—these buildings lack the site speciicity and intelligent solar-control strategies of the Deere Headquarters. Although Saarinen died in 1961 at the age of ifty-one, before

the completion of many of his largest com-missions, his posthumous inluence was evident in the work of architects who emerged from his ofice to form their own practices, including Kevin Roche (who oversaw com-pletion of the Deere complex in Saarinen’s absence), Gunnar Birkerts, and Cesar Pelli. The multilayered metal-and-glass curtain wall of the Deere Headquarters has likewise been an enduring inluence on architects, as is apparent in several of the contemporary case studies featured later in this book.

Following in the footsteps of pioneering work by Saarinen and others, relective coated glass came into widespread use in curtain walls in the late 1960s and into the 1970s, though not often treated with the sen-sitivity that Saarinen’s buildings displayed. An interesting example is the College Life Insurance Company Building (1971) in Indianapolis, Indiana, designed by Roche and John Dinkeloo. The building consists of three linked pyramidal volumes, each eleven stories tall. [4.4] The towers are orga-nized with service cores in an L-shape along two perimeter concrete walls and open ofice space enclosed by two sloping, relective-glass curtain walls suspended from concrete loor slabs. This plan establishes a strong duality of opacity and relectivity, with the opaque core walls facing the nearby highway and the relective glass walls opening out toward the landscaped site. The simple yet unusual massing, combined with the relec-tivity of the glass surface, lends the building an overriding abstract quality, which would come to deine a new trend: the reincarnation of the glass box as a mirrored sculptural

4.4

4.4

College Life Insurance

Building, Indianapolis,

Indiana, Roche and John

Dinkeloo, 1971


object. Though originally well received by the press, the structure was not without its technical problems. Soon after the building was occupied, the curtain wall mullions were found to be inadequate to resist wind loads; problems of leakage and glass breakage occurred in about half of the building’s 4,000 insulating glass units, eventually requiring complete replacement of the curtain wall.4

Another, much larger example of the shift toward the abstract, scaleless curtain wall is found at the sixty-story John Hancock Tower (1976) in Boston, Massachusetts, primarily designed by Henry N. Cobb of I. M. Pei and Partners. [4.5] The tower is a surreal variation on the midcentury glass box, with two-way transparency exchanged for one-way relectivity and the pure rectan-gular plan warped into a rhomboid shape. The curtain wall consists of more than 10,000 large panels of relective coated glass (originally insulating glass, but later replaced with monolithic glass) supported in a grid of extruded-aluminum mullions. The glass panels, measuring about 4.5 by 11.5 feet (1.4 by 3.5 meters), extend continuously from loor to loor with no spandrels (a condition made possible by the inclusion of sprinklers and other life-safety measures).5 [4.6] The Miesian I-shaped mullion is still present, but rather than projecting outward from the glass surface, it is subsumed into the wall, in service to the ideal of a totally lush surface. The John Hancock Tower was con-troversial in nearly every respect, from its siting on the edge of historic Copley Square to its height and facade treatment. Perhaps its greatest controversy involved a famous

4.5

4.6

4.5 + 4.6

John Hancock Tower,

Boston, Massachusetts,

I. M. Pei and Partners,

1976


4.7

4.8

4.7 + 4.8

Willis Faber and Dumas

Building, Ipswich,

England, Foster +

Partners, 1975


glass failure: during a strong storm in January 1973, with the building nearing completion, dozens of glass lites broke and fell down along the west facade, further damaging hundreds of additional lites. The origin of the failure was determined to be related to stresses caused by thermal expansion of the large insulating glass panels, and eventually all of the glass was replaced with new monolithic tempered lites.6 In a thorough review of the newly completed building and its complicated his-tory of glass breakage, critic William Marlin appreciated the tower’s “clean, crisp surfaces” despite its technical troubles, observing that “when the play of light and clouds is right, the building verges on the ethereal, almost disappearing.”7 To many other critics, how-ever, the 1970s mirror-glass ofice building, typiied by the John Hancock Tower, was “as forbidding, anti-social, and hostile as a person wearing mirror sunglasses.”8

Norman Foster achieved a major advance-ment in the quest for a continuous glass skin—a modernist holy grail since Mies’s 1921 project—in his design of the Willis Faber and Dumas Headquarters (1975) in Ipswich, England. [4.7] Amorphous in plan but follow-ing the shape of the site, the three-story ofice building is enclosed in a continuous wall of glass; remarkably, it utilizes no metal mullions for support. Recognizing the inherent tensile strength of glass, the entire curtain wall is hung from a rail along the roof of the build-ing, with each piece of glass bolted to the one above with stainless-steel patch plates. For lateral stability, monolithic glass ins are hung from the underside of each cantile-vered loor slab. [4.8] With no mullions or

glazing frames, the glass-to-glass joint is minimized to the width of a silicone seal. At the sidewalk, the glass disappears into a slot in the pavement, a further testament to the rigor of the all-glass design. The half-inch-thick tempered glass is bronze-tinted and relective, resulting in a stark contrast between its daytime and nighttime appear-ance, while the overall design strikes a balance between abstraction and technological showboating. Although not practical for tall buildings, Foster’s suspended glass-in wall has since been used extensively in smaller-scale buildings and discrete spaces such as lobbies and storefronts, and it has been adapted for use with insulating glass and various other structural backup sys-tems, such as cable trusses and nets.

Structural silicone glazing was another technology that became important in the drive to minimize framing while maximizing glass surface area. The concept of using sili-cone sealant as a means of ixing glass to its supporting mullion—essentially gluing the glass onto its frame with no other mechani-cal means of attachment—had irst been proposed in the 1960s. After extensive testing and small-scale applications, structural sili-cone came into mainstream use in the United States in the 1980s. The prismatic Allied Bank Tower (1986) in Dallas, Texas, designed by I. M. Pei and Partners, was at the time of its completion the tallest structural silicone-glazed curtain wall in the world, with more than 450,000 square feet (42,000 square meters) of surface area.9 [4.9 + 4.10] This ifty-nine-story steel-framed tower is clad entirely in relective green-tinted glass that

4.9 4.10

4.9

Allied Bank Tower,

Dallas, Texas, I. M. Pei

and Partners, 1986

4.10

Mullion plan details at

spandrel glass (left) and

vision glass (right)


is structurally glazed, on all four sides, to frames of anodized extruded aluminum. The curtain wall units were assembled in a factory to ensure the essential precision and quality control required for structural silicone application. Prior to installation, a mock-up of the curtain wall was tested for resistance to wind pressure and rain, and once installed, the curtain wall units were tested on site to conirm adequate perfor-mance.10 These procedures relect a growing understanding of the science of the curtain wall as well as increased expectations for performance. Testing of custom curtain walls, both in mock-ups and in the ield, is standard practice today.

As the modern curtain wall veered in the direction of relective abstraction, some architects began to experiment with an alter-native design vocabulary to challenge the dominance of modernism. Though its precise deinition has been much debated, the term postmodernism emerged to describe a new movement that reached its pinnacle of inlu-ence in the 1980s. As journalist and historian William Curtis described the phenomenon in 1984, “The mission is to save the American city from an excess of industrial standardization and the abstract glass box. The prognosis is in the use of metaphors and historical asso-ciations.” 11 Philip Johnson’s AT&T Building (1984), in New York City, is emblematic of the values and priorities of postmodernism: a rebuke of modernist dogma in favor of overt historicism, vernacular references, a jokey demeanor, and pop iconography. Johnson, who had worked with Mies on the design of the Seagram Building twenty-ive years ear-lier, reconceived the commercial skyscraper as a stone monument with a pedimented crown, the glass reduced to relatively small windows punched into massive opaque walls. Although projecting a traditional masonry aesthetic, the thirty-six-story AT&T Building still relies on a steel frame structure; the stone cladding is merely a nonstructural skin—a curtain wall. Granite panels, varying from two to ive inches thick, are individu-ally anchored to a back-up structure of vertical steel tubes spanning from loor to loor.12 In this way, even as the purity of the “glass box” aesthetic lost favor, architects found the curtain wall to be a neutral tech-nology, adaptable to wide array of design ideologies, even those with short life spans.

Around the same time that postmodern-ism was making its impact on architectural

fashion under the leadership of Philip Johnson, a small but remarkable building in upstate New York quietly forged an impor-tant new direction, dealing with issues that would become increasingly urgent in com-ing decades. The Hooker Ofice Building (1980), later known as the Occidental Chemical Building, by Cannon Design, is a nine-story cube situated along the Niagara River in Niagara Falls, New York. [4.11 + 4.12] The deining feature of this building is its double-skin glass curtain wall. The project’s dual goals of energy eficiency and maximization of views led the architects to the concept of a double-envelope. [4.13] Maximizing glass area on the facades would provide the desired views and decrease necessity for artiicial lighting. The inherent problem of heat loss during winter would be addressed by creat-ing an insulating air cavity between two walls of glass. The potential for overheating during summer would be diminished by incorporating adjustable sunshade louvers and natural ventilation in the cavity. Using solar cells, the louvers track the sun, adjust-ing automatically (with manual override) to maintain optimum solar control. The outer and inner skins, separated by a space of 4 feet (1.2 meters), comprise simple curtain walls with white-painted extruded-aluminum mullions on 5-foot (1.5-meter) centers. A cat-walk within the cavity provides access at each level for maintenance. The outer skin incorporates green-tinted insulating glass, while the inner is loor-to-ceiling clear glass. [4.14] A review in Progressive Architecture three years after the building’s completion found it to be an “energy tour de force.” The expected mechanical systems contract had been cut nearly in half, the building came in under the owner’s original budget, and the gas-ired boiler had never been used for heat.13 The Hooker Ofice Building’s double-skin curtain wall was incredibly prescient. With dramatic results, it intelligently combined Le Corbusier’s earlier visions of the neutral-izing wall and the brise-soleil. Unfortunately, due to apparent neglect and lack of tenants, the building has fallen into disrepair. It still stands, however, as an important precedent for architects struggling to resolve the some-times dueling demands of experiential quality and energy eficiency.

In naming Jean Nouvel the Pritzker Prize Laureate of 2008, the jury cited the archi-tect’s “courageous pursuit of new ideas and his challenge of accepted norms in order


to stretch the boundaries of the ield.” 14 These qualities are apparent in the project that irst brought Nouvel to international attention: the Arab World Institute (1987) in Paris.15 [4.15] Built as part of the Grand

Projets program initiated by French presi-dent François Mitterand in the early 1980s, the institute is best known for its unique and highly complex curtain wall design. On the south facade of the building, Nouvel deploys a sun-shading device that is integral with the curtain wall and imbues it with a character that is not merely functionalist but also symbolic and poetic. The curtain wall itself consists of conventional double-pane insulating glass, set within prefabricated story-high units of extruded aluminum fram-ing and suspended outside the building’s structural frame. Behind the insulating glass, however, is a unique layer of shutter mecha-nisms, similar in operation to those in a camera lens. These shutters, or diaphragms, were originally equipped with photocells that measured the amount of sunlight striking the glass, automatically opening or closing the shutters to maintain optimal interior conditions. On the interior side of the curtain wall, the shutter mechanisms are protected by a layer of monolithic clear glass that can be opened for maintenance access. The artic-ulation of the shutters within the glass simul-taneously references traditional Arabic latticework decoration, known as mouchara-

bieh, while responding to the environmental conditions of a south-facing facade, achieving both through the introduction of high-tech gadgetry. The eventual malfunctioning of the shutter system, with its hundreds of

thousands of moving parts, was perhaps inevitable. Many of the diaphragms no longer move at all, due in part to limited mainte-nance budgets, and those that do move are now controlled by a central computer rather than the original photocells.16 Despite such setbacks, the Arab World Institute—like the Hooker Ofice Building before it— was an important experiment, promoting the notion of an intelligent curtain wall system that could automatically respond to changing environmental conditions while presenting a unique aesthetic expression.

Nouvel’s approach is characterized by experimentation and a faith in contempo-rary solutions. He has said:

My interest has always been in an architec-

ture which relects the modernity of our

epoch as opposed to the rethinking of histor-

ical references. My work deals with what is

happening now—our techniques and mate-

rials, what we are capable of doing today.17

Another inluential project by Nouvel, in which he explicitly explores the techniques, materiality, and potential immateriality of the glass curtain wall, is the headquarters for the Cartier Foundation (1994) in Paris. [4.16] This eight-story steel-framed building houses a ground loor art gallery with ofices above and parking below. The design is an interesting exploration of layered space, and it plays with the visual effects of alternating transparency and relectivity. The building itself is set back from the street and enclosed with a curtain wall of clear insulating glass. Retractable fabric blinds are hung outside

4.11 + 4.12

Hooker Office

Building, Niagara Falls,

New York, Cannon

Design, 1980

4.13

Typical floor plan

4.14

Wall section

4.11

4.13

4.14

4.12


of the glass to control solar heat gain and glare. [4.17] The glass walls extend horizon-tally and vertically beyond the bounds of the interior space, creating free-loating planes of glass. Another freestanding glass curtain wall, similar in module and materiality, is located along the sidewalk, literally mirror-ing the building wall beyond it and creating an exterior space enclosed on two sides by glass. The result of this series of parallel curtain walls is an intriguing and ambigu-ous visual appearance—one is not certain which walls enclose space and which do not. The building suggests an afinity with the work of artist Dan Graham, whose steel and glass pavilions likewise explore the effects of transparency and relectivity on the expe-rience of space.18 At the Cartier Foundation, these effects draw passersby into the site to explore the ground-loor gallery and courtyards, which are open to the public. The curtain wall is thus employed not only for the enclosure of a building but also for rhetorical effect, exploiting the glass curtain wall’s ability to physically divide while visually connecting disparate spaces.

The conditions of transparency and relec-tivity dominated architectural discourse on building envelopes for much of the twenti-eth century, motivated by technical as well as aesthetic and experiential impulses. By the end of the century, however, there was a palpable interest among certain architects to work with the more complicated condition of translucency. This tendency was given ofi-cial recognition by the Museum of Modern Art in New York City, with its 1995 exhibition Light Construction, featuring several projects

from around the world that explore concepts of luminescence in architecture and art. In many of these projects, various glass fabrication techniques—acid-etching, sand-blasting, laminating, and casting—were used to transform glass from an “invisible” transparent surface to a material with depth and presence, one that does not simply transmit or relect light but collects and scat-ters it, producing a diffuse glow and hazy shadows. The idea of a translucent glass skin is certainly not without precedent in modern architecture. Earlier examples include the Maison de Verre (1932) in Paris by Pierre Chareau and Bernard Bijvoet, the Museum of Modern Art (1939) in New York City by Philip S. Goodwin and Edward Durrell Stone, and the Johnson Wax Building Research Tower (1951) in Racine, Wisconsin, by Frank Lloyd Wright. [4.18 + 4.19] Two buildings from the late 1990s stand out as innovative reinterpretations of this tradition: the Kunsthaus (1997) in Bregenz, Austria, by Peter Zumthor, and the Kursaal Auditorium and Congress Center (1999) in San Sebastián, Spain, by Rafael Moneo.

The Kunsthaus is a contemporary art museum located near the shore of Lake Constance. [4.20 + 4.21] The building enve-lope is composed of two layers: an outer skin of translucent glass, which stands about 3 feet (90 centimeters) in front of an inner wall of concrete and glass. The outer layer, wrapping around all four sides of the build-ing, is constructed of hundreds of identical panels of laminated glass. The panels are supported not by continuous frames but by intermittent stainless-steel angles at

4.16

Arab World Institute,

Paris, France, Jean

Nouvel, 1987

4.15


the top and bottom corners of each panel. The glass, which has been given an acid-etched surface treatment, is arranged in a shinglelike manner, with the top and one side of each panel tilted behind the edges of the adjacent panels. Because the entire building is covered with these translucent glass “shingles,” there are no direct views into the building from the outside. Rather, there is the ambiguous suggestion of what lies beyond the surface—shadows of the ine steel substructure that supports the outer skin, faint indications of the concrete wall behind, and the diffuse glow of interior lighting at night. The Kunsthaus was among the irst buildings to use an exterior applica-tion of acid-etched glass, produced by pour-ing a chemical bath onto its surface for a predetermined amount of time to create a microscopically roughened surface to scat-ter light rays and transform the normally relective glass to a matte inish. Of the external character of the curtain wall, Zumthor wrote, “It absorbs the changing light of the sky, the haze of the lake; it relects light and color and gives an intimation of its inner life according to the angle of vision, the daylight and the weather.”19 The interior spaces of the Kunsthaus are the true benei-ciaries of Zumthor’s ingenious approach to the manipulation of daylight. The walls of the galleries are made of concrete, while the ceilings consist entirely of suspended acid-etched glass panels. Above each ceiling is an eight-foot tall cavity with perimeter clere-story glass that transmits natural daylight from the outer glass curtain wall to the translucent ceiling, creating a glowing effect

4.16 + 4.17

Fondation Cartier, Paris,

France, Jean Nouvel,

1994

4.16

4.17


that changes with external environmental conditions. The result is subtle yet power-ful, serving the function of displaying art while also creating an indirect connection to the outside world.

The Kursaal Auditorium and Congress Center by Rafael Moneo occupies a promi-nent site in the seaside town of San Sebastián, Spain, where the city grid, the Urumea River, and the Bay of Biscay converge. In response to this dramatic setting, Moneo conceived the building as an element of the landscape, like “two gigantic rocks stranded at the mouth of the river, forming part of the land-scape, rather than belonging to the city.”20 The Kursaal consists of two prismatic vol-umes, one containing a large concert hall and the other a smaller auditorium; they are essentially buildings within a building. [4.22] The concert hall and auditorium each sit within a larger shell, clad almost entirely in a unique curtain wall system of translu-cent glass panels. [4.23] Like the Kunsthaus, the Kursaal’s envelope is a double skin. A cage of load-bearing structural steel frame-work, approximately eight feet (2.4 meters) deep from inside to out, supports an exterior skin of concave glass planks and an interior skin of lat, sandblasted low-iron glass. Complex combinations of different glass treatments and surfaces were necessary to achieve the intended effects. The outer glass skin is a composite of two different glass types, bent and laminated together, and sup-ported by horizontal aluminum mullions anchored to the steel structure. The outer layer in the laminated assembly is com-posed of luted textured glass, produced

by heating and passing the glass over patterned ceramic rollers to impress the ribbed proile, while the inner is a low-iron-content glass with a sandblasted surface treatment. The appearance of the curtain wall changes dramatically with its atmo-spheric context—in direct sun it becomes opaque and solid; with sunlight behind it, it mysteriously reveals its depth in shadow; at night it glows, relecting off the waters of the river and sea. [4.24]

In a 1997 Architecture magazine article, the curtain wall is identiied as “an architect’s most substantial design outlet,” the part of the building design in which architects take their most creative liberties.21 This senti-ment relects the growing menu of glass products and surface treatments available from fabricators, allowing architects to cus-tomize and ine-tune the performance and aesthetic effect of the curtain wall. The LVMH Tower (1999), in New York City, is emblem-atic of this phenomenon. Designed by Atelier Christian de Portzamparc in association with the Hillier Group, the LVMH Tower is a twenty-ive-story steel-framed building. Its ofices and showrooms are contained behind a complex skin of folded planes and varying glass types. [4.25] In the New

Yorker, Paul Goldberger called it the city’s “irst important small skyscraper in more than a generation,” remarking that the glass curtain wall “has a sculptural, emotional resonance that is very rarely achieved.”22 This sculptural quality is the result of a combination of two primary strategies: a geometrically complex form and a palette of unique glass treatments. The curtain

4.18

Museum of Modern Art,

New York, New York, Philip S.

Goodwin and Edward Durrell

Stone, 1939

4.19

Johnson Wax Research Tower,

Racine, Wisonsin, Frank Lloyd

Wright, 1951

4.18 4.19


wall (totaling approximately 45,000 square feet, or 4,200 square meters) consists of prefabricated units framed by extruded- aluminum mullions in a grid that warps and twists to follow the geometry of the facade. [4.26] In addition to regular clear glass, the curtain wall incorporates blue- and green-tinted glass, as well as ultra-clear low-iron glass. These base materials are further enhanced with surface treatments: custom-patterned sandblasting, ceramic frit dot patterns, and low-E coatings. In some areas, spandrels are completely eliminated in favor of loor-to-loor vision glass, made possible by the installation of sprinkler heads in the ceiling, located just inside the glazing. The LVMH Tower established a tradition of innovative, experimental cur-tain wall architecture among luxury goods companies, to be followed by a number of notable buildings in the early twenty-irst century: Herzog and de Meuron’s Prada Flagship Store (2003) in Tokyo, SANAA’s Dior Building (2004) in Tokyo, and Kengo Kuma’s LVMH Building (2004) in Osaka. [4.27–4.28]

In the early twenty-irst century, the issue of sustainability increasingly pervades our culture. In architecture, the concept encompasses a broad range of issues, includ-ing energy eficiency, responsible utilization of resources, and responsiveness to local climate, durability, and the creation of healthy environments. As the envelope of choice for many buildings, the curtain wall has a spe-ciic role to play in this developing paradigm. In assessing its current role, it is instructive to return to an inluential essay from 1981.

4.20 + 4.21

Kunsthaus, Bregenz,

Austria, Peter Zumthor,

1997

4.22

Kunsthaus, section

4.20

4.21

4.22


In “A Wall for All Seasons,” the architects Mike Davies and Richard Rogers give a critical reassessment of what could be called the modern architect’s long “love affair” with glass and transparency.23 Following the rise in public awareness of ecology as a science in the 1960s and the energy crises of the 1970s, the authors noted that architects must recognize the inherent environmental problems, such as excessive heat gain and loss, associated with widespread use of glass in certain climates. They argued, although Mies’s early experiments in glass architec-ture maintained an aesthetic appeal for architects, “We were caught admiring the concept but with our technological panties around our knees.”24 They posed a series of critical questions about the ideal of glass architecture and its emerging problems:

Mies’ wonderwall was heavily under

attack. Must we say goodbye to glass?

Can we never return to the transparent

skin? Has the pendulum begun to swing

back again towards the leaded lights in

the massive walls of yesteryear? Can we

stave off the problem by greater feats of

ingenuity? Can we ever evolve a new

architecture based upon intelligent

passive energy design?25

Davies and Rogers proposed a new for-mulation of the glass wall, which they called a polyvalent wall, that would dynamically respond to changing environmental condi-tions. New technologies, they believed, would forge the way. The authors also pre-dicted that the future of architectural glass

would rely on the development of new high-performance products with much greater thermal resistance. Although not yet real-ized to the extent called for by Davies and Rogers, the idea of interactivity in the build-ing envelope has become a key element in current concepts of the intelligent facade. As opposed to older notions of glass skin as static and inert—typiied by Mies’s 1920s projects as well as the relective, hermeti-cally-sealed single glass skins of 1970s ofice towers—a new incarnation of the glass wall has emerged in which the facade is designed to adapt automatically and intelligently in response to external and internal environ-mental conditions. In their 2003 book, Tower

and Ofice, the architects Iñaki Ábalos and Juan Herreros describe the current trans-formation of the curtain wall from a passive barrier to an active system:

In recent decades, the modernist glass skin—

absolute, thin, dematerialized, unique and

passive—has given way to another concept

of wall, one that is subjective, thick, palpa-

ble like landscape, double-layered, and active

from the point of view of energy. . . . It is the

site at which glass, climate control, and

the external environment assume congru-

ent and interactive roles.26

Glass is thus conceived not as a single distinct element but as one component in a system of enclosure. In such a system, the goal is for the low of energy to be controlled in both directions (inward and outward) to maximize internal comfort and minimize energy usage. The main components often

4.23 + 4.24

Kursaal Congress

Center, San Sebastian,

Spain, Rafael Moneo,

1999

4.23 4.24


include a double-skin glass envelope with variable sun-shading or diffusing elements and operable ventilators, and can include power-generating components such as photovoltaic cells or wind turbines. In addi-tion to the buildings mentioned earlier, examples of multilayered facades may be found in buildings such as Foster + Partner’s Business Promotion Centre (1993) in Duisburg, Germany; the Renzo Piano Building Workshop’s Debis Headquarters Building (1997) in Berlin; Murphy/Jahn Architect’s Deutsche Post Tower (2003) in Bonn, Germany; and in several of the case studies included in this book. These new facade systems are often integrated directly with the building’s mechanical systems to create a holistic, eficient building response to cli-mate and energy. It should be recognized, however, that even the highly sophisticated double-skin glass curtain walls of recent years often do not measure up, in terms of performance, to the alternative of highly insulated opaque walls.27 Nevertheless, in the spirit of architectural futurism (and

therefore in the tradition of Paul Scheerbart), in the 2002 book Intelligent Skins, Michael Wigginton and Jude Harris predict, “The intelligent facade will be one of the principal elements in the building of the future.”28 Indeed, many architects today continue to work collaboratively with engineers and building scientists toward deining and real-izing the intelligent facade, within the ever-present constraints of available technology, constructability, and cost. In an era increas-ingly deined by a sense of impending envi-ronmental crisis, the aesthetic dissolution of the wall has given way to a rethinking of priorities, a rebuilding of the wall, and a critical new role for glass as a material.

The Genzyme Center (2003) in Cambridge, Massachusetts, is a twelve-story ofice building that boldly addresses some of these issues in an integrated fashion. Working with a consultant team and an enlightened developer and tenant, Behnisch Architekten conceived the building as an opportunity to implement green technologies in the service of not only energy eficiency

4.25 4.26

4.25 + 4.26

LVMH Tower, New

York, New York,

Atelier Christian

de Portzamparc in

association with the

Hillier Group, 1999


but also enhanced user experience and eco-nomic return. The design strategies include a double-skin glass curtain wall with auto-mated sunshade blinds, roof-mounted heliostats that relect sunlight into a central atrium, and photovoltaic arrays for supple-mental electricity generation. The interior spaces are lit primarily by daylight entering through either the perimeter curtain wall or the atrium, and photo-sensors automati-cally dim the light ixtures when daylighting is suficient. The double-skin curtain wall is used mainly on the west and south facades, with a 4-foot (1.2-meter) interstitial air cavity acting as a buffer between interior and exte-rior. In winter solar radiation heats the air cavity, while in the summer it is naturally ventilated. Operable windows are used throughout the curtain wall, and, on cool summer nights, the windows can be auto-matically opened by a central building man-agement system to purge accumulated heat from the building. Working together, these systems are projected to reduce the build-ing’s overall energy cost by 41 percent.29 The Genzyme Center was well received within the architectural ield as an innovative prototype. The building achieved a LEED

Platinum rating from the U.S. Green Building Council and was selected as an AIA Top Ten Green Project for 2004. Peter Davey, in Architectural Review, called the Genzyme Center “an inspiring shift in the evolution of the ofice building type, more inventive and integrated than almost anything yet built.”30

As evidenced by the Genzyme Center and other recent high-proile projects, among contemporary architects and engineers there is a renewed interest in the concept of sustain-able architecture. The signiicant improvement of energy eficiency has become one of the primary goals in contemporary curtain wall design; however, as William McDonough points out, “Being less bad (or more eficient) is not necessarily being good.”31 It is likely that we will soon see a major shift in emphasis, from designing buildings that are simply more energy eficient to conceiving and implementing new technologies that allow buildings to actually sustainably generate energy (making a positive difference and not simply a less negative one), and it can be expected that the building envelope, as the interface between exterior and interior environments, will continue to play an essential role in this pursuit.

4.27 4.28

4.27

Prada Flagship Store,

Tokyo, Japan, Herzog

and de Meuron, 2003

4.28

Christian Dior

Omotesando Building,

Tokyo, Japan, SANAA,

2004


Endnotes

1 “Bold and Direct, Using Metal in a Strong, Basic Way,” Architectural Record, July 1964, 136–137.

2 Ibid., 140.3 This is according to a Kinney Vacuum Coating

advertisement in the 1966 Sweets Catalog. The advertisement also features an image of the John Deere & Company Headquarters.

4 See Patrick Loughran, Falling Glass: Problems

and Solutions in Contemporary Architecure (Boston: Birkhäuser, 2003), 115–116.

5 Ibid., 119.6 Ibid., 121.7 William Marlin, “Some Relections on the

John Hancock Tower,” Architectural Record, June 1977, 123.

8 Marvin Trachtenberg and Isabelle Hyman, Architecture: From Prehistory to Post-Modernism (New York: Henry N. Abrams, 1986), 546.

9 “World’s Tallest Silicone-Glazed Curtain Wall,” Buildings (December 1984), 36.

10 See Christopher Olson, “Dramatic Geometry Challenges Project Team,” Building Design &

Construction, September 1987, 102–106.11 William Curtis, “Principle v. Pastiche:

Perspectives on Some Recent Classicisms,” Architectural Review, August 1984, 14.

12 See Susan Doubilet, “Not Enough Said,” Progressive Architecture, February 1984, 70–75.

13 John Morris Dixon, “Glass Under Glass,” Progressive Architecture, April 1983, 82–85.

14 “Media Kit Announcing the 2008 Pritzker Architecture Prize,” http://www.pritzkerprize.com/full_new_site/nouvel/mediareleases/08_media_kit.pdf, 3.

15 An extensive and insightful analysis of Nouvel’s work in Paris can be found in Fierro, The Glass

State, 95-149.16 See Loughran, Falling Glass, 88.17 “Media Kit Announcing the 2008 Pritzker

Architecture Prize,” 3.18 This connection is also observed by Fierro

in The Glass State, 117.

19 Peter Zumthor, Kunsthaus Bregenz (Ostildern: Hatje, 1999), 13.

20 José Rafael Moneo, The Freedom of the Architect (Ann Arbor, Mich.: University of Michigan Press, 2002), 30.

21 Anne C. Sullivan, “Customizing the Curtain Wall,” Architecture, January 1997, 124.

22 Paul Goldberger, “The Sky Line: Dior’s New House,” the New Yorker, January 31, 2000, 88.

23 Mike Davies and Richard Rogers, “A Wall for All Seasons,” RIBA Journal 88, no. 2 (February 1981): 55–57.

24 Ibid., 55.25 Ibid., 55.26 Ábalos and Herreros, Tower and Ofice, 40.27 See John Straube, “A Critical Review of the Use

of Double Facades for Ofice Buildings in Cool Humid Climates,” Journal of Building Enclosure

Design (Winter 2007): 48–52. Straube inds that double facades provide a transparent all-glass aesthetic at signiicant cost; other, less expensive solutions, such as a reduction in the area of glazing, are just as technically valid if not more so.

28 Michael Wigginton and Jude Harris, Intelligent

Skins (Oxford: Butterworth-Heinemann, 2002), 43.29 U.S. Green Building Council,

http://leedcasestudies.usgbc.org/energy cfm?ProjectID=274.

30 Peter Davey, “Luminous Paradigm,” Architectural Review, April 2004, 64.

31 William McDonough and Michael Braungart, “Eco-Effectiveness: A New Design Strategy,” Sustainable Architecture White Papers (New York: Earth Pledge Foundation, 2000), 3.

Essay Title 64

Part II: Performance and Technique

5

6

Curtain Wall System Design

The Building Envelope as Selective Filter

66Part II: Performance and Technique

5

Curtain Wall System Design

5.1

67Curtain Wall System Design

utilizing a hierarchy of frames and panels. The main components are typically mul-lions, inill panels, and anchors. The vertical and horizontal mullions—usually fabricated out of extruded aluminum, due to its rela-tively high strength-to-weight ratio—form the structural frame of the curtain wall and are analogous to the building’s structural frame of columns and beams. Although variations are common, the primary mul-lions typically span vertically from one loor to the next, with intermediate horizontal mullions spanning between the verticals. In other words, the mullions form the frame-work in which the inill panels—glass, metal, stone, or other materials—are set. The proper detailing of the joint between the inill material and the mullion is essential. [5.2 + 5.3] Glass is most often held in its frame with continuous rubber gaskets or silicone seals, or alternatively by point it-tings drilled into the glass. Metal and stone panels may require secondary anchor clips or other means of attachment to support the weight of the panel, while also relying on gaskets or seals to create a watertight joint. Inill panels may be classiied as either vision or spandrel panels, depending on the level of transparency and the desire for views through the curtain wall. While vision panels obviously rely on glass, spandrel panels may be glass, metal, stone, terra-cotta, or nearly any other opaque material, usually backed with an air cavity, a sealed back pan, and insulation. The network of assembled frames and inill panels is connected to the primary building structure by an anchor system. The typical curtain wall anchor,

In contemporary practice, the curtain wall is typically conceived as a system—that is, as a coordinated assemblage of components designed to perform in a speciied way. The relative success or failure of a curtain wall, in terms of both aesthetics and technical per-formance, may often be traced to the selection and detailing of its components. Following the irst large-scale experiments with metal frames in the 1950s, a curtain wall industry emerged that, through continual research and development, has helped advance the technology and codify its materials and methodologies.1 This has, in turn, led to the increasing sophistication and variety in cur-tain wall systems that characterizes the current ield. Today, the successful design of a curtain wall system requires extensive knowledge of materials and appropriate detailing; an accurate assessment of the building’s anticipated environmental condi-tions (both interior and exterior); a compre-hensive understanding of the required performance; and a clear strategy for the relationship of the curtain wall to the build-ing structure. Given the complexity of most contemporary systems, architects often approach the design process with a strategy of collaboration, consulting closely with a team of experts that may include facade specialists, engineers, and, in some cases, curtain wall fabricators and contractors.

In general terms, the curtain wall is essentially a framework that can incorpo-rate multiple variations in materials, form, and function. [5.1] Despite the great variety of expression, most curtain walls are based on fundamental principles of design,

5.2 5.3

5.1

Curtain wall as frame-

work, incorporating

multiple variations in

material and form

5.2

Glass supported by

aluminum mullions, with

external glazing cap

running horizontally and

structural silicone seal-

ant running vertically

5.3

Glass supported by

countersunk stainless-

steel point fittings


fabrication and installation. Although hybrid combinations are possible, most cur-tain walls fall into one of two main catego-ries: the stick system or the unit system.

In a stick-system curtain wall, the indi-vidual components are assembled piece by piece (or stick by stick) on the construction site. [5.4] First, the primary mullions are anchored to the building structure, followed by the installation of any intermediate mul-lions spanning between primary members, and inally the inill panels are installed, along with other secondary components, such as shading devices or ornamental ins. Most stick systems are standard, off-the-shelf products and therefore have relatively low material cost. Another advantage of the stick system is the low expense of shipping and handling due to the ability to eficiently package and transport the separate compo-nents. The main disadvantages of the stick system derive from the method of assembly in the ield, which generally involves a slower pace, higher labor costs, and a greater poten-tial for problems concerning the quality and precision of the work compared to factory prefabrication. Stick systems are usually limited to low- or mid-rise applications. [5.5]

A unit system (or unitized) curtain wall consists of prefabricated modules that are assembled under controlled factory condi-tions and then shipped to the construction site and connected to preinstalled anchors on the building structure. [5.6] Although many variations are possible, a typical cur-tain wall unit is between 4 and 10 feet (1.2 and 3 meters) wide by one to two stories tall, anchored at each loor slab or beam.

consisting of metal angles or channels bolted to each vertical mullion and to the edge of the loor slab, transfers wind loads and dead loads from the wall system to the building’s structural frame. The anchor must also accommodate the anticipated tolerances and movement of the structure to which it is attached, allowing adjustment in three dimensions (x, y, and z axes).

Based on the extent to which the system design is unique, a curtain wall may be classi-ied as either standard or custom. Numerous manufacturers offer a wide variety of stan-dard off-the-shelf curtain wall systems, the components of which may be selected from a catalog, with predetermined and pre-tested details.2 Such systems are generally less expensive and may offer some means of limited customization through an optional kit-of-parts approach (with different glass types, mullion proiles, etc.). Standard systems are usually selected for smaller-scale or smaller-budget projects, or for curtain walls without unique performance or aesthetic requirements. Custom systems, on the other hand, are individually designed and built, usu-ally for a single building (or a group of related buildings) with a more generous budget and more elaborate goals for technical perfor-mance or aesthetic expression. Custom sys-tems generally require extensive testing and quality control throughout the design and construction process, while standard systems, which have been previously tested and docu-mented by the manufacturer, require less.

In addition to the custom and standard distinctions, curtain wall systems are further classiied according to their methods of

5.4 5.5

5.4

Stick-system curtain wall,

components installed

piece by piece on site

5.5

Stick-system curtain wall

5.6

Unit-system curtain wall,

with units prefabricated

in shop, transported to

site, and anchored to

building structure

5.7

Installation sequence

for a unit-system

curtain wall

5.8

Installation of unit-

system curtain wall

at Trump Tower, in

Chicago, Illinois


Because each curtain wall unit arrives fully glazed on site, with all framing and inill panels complete, ield labor is minimized. The advantages of the unit system therefore include greater quality control during fabri-cation and quicker on-site installation, as well as a greater ability to accommodate building movement caused by delection or wind loads. The disadvantages of the unit system include higher shipping costs and the necessity for sequential installation. (Because of the way that one unit interlocks with the next, the units must be installed in a particular sequence; whereas stick systems permit more freedom.) Unit systems are typically selected for high-rise and high- volume curtain walls and, in some cases, for smaller buildings with generous budgets. [5.7 + 5.8]

The differences in assembly methods between these two systems become evident in the details. Typical mullion plans for a stick-system and a unit-system curtain wall reveal key detailing strategies. Both mullions described here consist of extruded-aluminum sections that span vertically from one loor to the next, spaced ive feet (1.5 meters) on center, with an inill of double-pane insulat-ing glass. As noted previously, aluminum has a high strength-to-weight ratio (desirable when trying to create a lightweight wall); it also accepts a wide variety of inishes such as painting and anodizing and is well suited for the process of extrusion, in which heated aluminum is forced through a series of dies to create a speciied shape. The stick-system mullion [5.9] is extruded in a rectan-gular box shape with recessed channels

5.7

5.8

5.6


degree of precision and quality control is required in the application of the silicone sealant, and therefore the use of four-sided structural glazing is limited to unit systems that are prefabricated in controlled factory conditions and is not advisable for ield-assembled stick systems. Unit systems may also utilize the more traditional, captured glazing method with a pressure plate and exterior cap. Extruded aluminum is the fram-ing material of choice for most curtain walls, but multiple variations are possible. [5.11]

Although curtain walls can incorporate a wide array of inill materials, glass is by far the most common. The speciication and detail-ing of glass in curtain walls has become quite complex in recent years, as the industry, responding to a broad range of technical and aesthetic demands, has begun to offer an ever-expanding menu of products and fabri-cation options. An important distinction can be made between primary production and secondary fabrication of architectural glass. The production of glass refers to the primary process of making large sheets of glass, which are then fabricated—via secondary processes—into various types. For instance, the vast majority of architectural glass today is produced by the loat process, a fully mechanized procedure in which the raw materials of glass (silica sand, soda ash, lime, and other ingredients) are melted at a tem-perature of about 3,000°F and then loated onto a bath of molten tin, forming a continu-ous ribbon that is eventually cooled and cut into large sheets of lat glass.3 By varying the mineral composition of the raw materials, loat glass can be produced in a range of

that accept continuous gaskets along the front edge. After this mullion has been anchored to the loor slab and horizontal mullions have been installed, the glass panel is set in place and held against the mullion by an extruded-aluminum pressure plate that is intermittently screwed into the mul-lion, exerting pressure through gaskets and mechanically ixing the glass to the frame. The pressure plate is often separated from the mullion itself by a plastic or rubber thermal break, intended to limit heat loss. On the exterior, the pressure plate can be covered by a cap (also made of aluminum), which snaps onto the plate, concealing the fasteners and forming the exterior inished surface of the mullion. Whereas the stick-system mullion is a single, uniied member, the unit-system mullion is composed of two adjacent unit frames that interlock to form the vertical member. [5.10] Known as a dynamic (or split) mullion, this two-part extruded-aluminum mullion allows some relative movement between adjacent units (for thermal expansion and contraction) and gives the system greater lexibility in general. Gaskets are used to provide a seal at joints where two unit frames come together. The detail shown here incorporates four-sided structural silicone glazing, a method in which the glass is essentially “glued” onto its frame using high-strength silicone in lieu of an exterior pressure plate and cap. In addition to the aesthetic effect of a continu-ous, lush glass surface, this method limits the potential for heat loss through the metal frame by minimizing the amount of metal exposed to the exterior. Obviously, a high

5.9 5.10

5.9

Stick-system curtain wall

mullion, typical plan

detail

5.10

Unit-system curtain wall

mullion, typical plan

detail


Laminated glass, therefore, is often used in museums, galleries, and libraries, even when conditions do not require safety glass. For custom aesthetic applications, interlay-ers can be printed with photographic images, patterns, colors, or text. The laminating pro-cess can also be used to encase photovoltaic cells between two glass panes for electricity generation. [5.13] Like many secondary processes, glass lamination is labor inten-sive and adds signiicant cost.

Glass produced by the loat process is also known as annealed glass. Through the secondary processes of heat-treating, the strength characteristics of loat glass may be improved, resulting in either heat-strengthened (HS) or fully tempered (FT) glass. This process involves heating a piece of glass to a set temperature and then cool-ing it again very quickly under controlled conditions, creating a compression enve-lope around the glass surface and edges, with an internal tension layer at the center. This results in increased glass strength and load resistance. HS glass has approximately two times the strength of annealed glass of the same thickness. FT glass (also known as toughened glass), which is produced in a method similar to that of HS glass but is cooled much quicker, has about four times the strength of annealed glass of the same thickness. HS and FT glass thus offer means of increasing glass strength without increas-ing thickness. When FT glass is broken, it breaks into many small fragments with dull edges (as opposed to the large, sharp pieces of annealed and HS glass) and therefore usually qualiies as safety glazing. [5.14]

integral color tints—from regular clear glass (which has a slightly greenish tint) to shades of bronze, gray, blue, and green. In low-iron (or “water white”) glass, the greenish tint of regular clear glass is elimi-nated by reducing the iron content in the batch of raw materials. In addition to various tints, the loat process produces sheets of varying thicknesses. Standard thicknesses for architectural glass range from an eighth of an inch (three millimeters) to three-quarters of an inch (nineteen millimeters).

The glass sheets produced by the loat method can then be fabricated into numer-ous other products through such secondary processes as laminating, heat-treating, coat-ing, insulating, ceramic fritting, acid-etching, sandblasting, bending, or nearly any combi-nation of the above. [5.12] Laminated glass consists of two or more pieces of glass per-manently bonded together with an interlayer of cured liquid resin or plasticized sheet material (polyvinyl butyral or polycarbon-ate) fused to the glass through heat and pressure. Laminated glass generally quali-ies as safety glazing, because if the glass breaks, the fragments tend to adhere to the interlayer (reducing the potential for dan-gerous fall-out) and the interlayer resists the passage of objects or people through the glass plane. This is why most building codes require the use of laminated glass in over-head glazing applications such as skylights and glass loors. An added beneit of the common interlayer of polyvinyl butyral is its ability to block a high percentage of the sun’s ultraviolet (UV) rays, which can cause damage to artwork, fabrics, and paper.

5.12 5.13

5.11

5.11

Possible variations in

mullion material, from

left: steel T, steel pipe,

aluminum, and wood

5.12

Glass-fabrication

options, from left:

monolithic glass,

laminated glass,

insulating glass,

laminated insulating

glass, and triple-pane

insulating glass.

5.13

Glass laminated with

photovoltaic cells


In its original state, loat glass, which may be referred to as monolithic or single-pane glass, is inherently ineficient in terms of ther-mal insulation, and except in mild climates without extreme temperature variations, it is insuficient for most architectural applica-tions. Insulating glass units consist of two or more panes of glass separated by spacers to create sealed interstitial air cavities, ranging from a quarter to three-quarters of an inch in depth, greatly improving thermal performance. The typical coniguration includes an alumi-num spacer illed with desiccant and sealed to each pane with a primary vapor seal of polyisobutylene. A secondary seal of struc-tural silicone holds the two panes together. Because the metal spacer is a good conductor of heat, the edges of an insulating glass unit are the most vulnerable to unwanted heat loss. When improved performance is required, alternative “warm edge” spacers with better insulating properties than aluminum, such as stainless steel and thermoplastic spacers, may be speciied.

Insulating glass units may also incorpo-rate various glass surface treatments to fur-ther transform the basic loat glass. Relective and/or low-emissivity (low-E) coatings can signiicantly improve the solar-heat-gain coeficient and thermal insulating properties of glass. Ceramic frit comes in assorted colors and can be silk-screened in custom patterns (most often, using dots or lines) then baked, to permanently fuse with the glass surface, creating different aesthetic effects as well as increased solar shading. Sandblasting and acid-etching can be used to create textured, translucent surfaces that diffuse light and

5.14

5.15


Endnotes

1 In the United States, the American Architectural Manufacturers Association has published a number of advisory documents related to curtain wall design and construction, including design guidelines, model speciications, testing proce-dures, and performance standards. Other related standards speciically relevant to curtain wall design have been developed by the American National Standards Institute, the American Soci-ety for Testing and Materials, and the Glass Asso-ciation of North America. Most countries have counterpart organizations that set standards for the design and testing of curtain walls.

2 Examples include manufacturers such as Archi-tectural Glazing Technologies, EFCO, Kawneer, Oldcastle Glass, Schüco, United States Alumi-num, and Visionwall.

3 See Bradford McKee, “Float Glass,” Architect, July 2007, 68–75.

obscure direct vision through the glass. [5.15] All of these secondary fabrication processes have an effect on the cost and the available sizes of glass. The maximum size of a particular product is usually limited by some combination of the manufacturing equipment on which it is fabricated, the weight of the inished product, or restric-tions on transporting the inal product.

This survey of glass-fabrication options illustrates that the design of a curtain wall system requires a broad knowledge of mate-rials, component fabrication, and installa-tion methodologies. In addition, the designer must also consider the performance charac-teristics of each component during the life of the building. In each curtain wall system described above, the speciic conigurations of the mullions and inill panels depend on a number of technical factors. The required dimensions of a mullion, for instance, must be calculated based on the material chosen, the spacing of the mullions, their overall span, and wind loads. The minimum glass thickness is inluenced by the dimensions of the individual pane, the glass type, its method of edge support, and wind loads. The minimum width of a bead of structural silicone sealant is determined by the rated strength of the silicone, the size of the pane, and the wind loads. Beyond these primary structural concerns, the design of a curtain wall system must also respond to a complex set of environmental performance param-eters, which will be discussed more fully in the next chapter.

5.14

Typical breakage

pattern of fully

tempered glass

5.15

Insulating glass with

custom-patterned

ceramic frit silkscreen

(suggesting foliage),

Utretcht University

Library, Utrecht, the

Netherlands, Wiel Arets

Architects, 2004

Part II: Performance and Technique 74

6

The Building Envelope as Selective Filter

BUILDING ENVELOPE INTERFACE

Meso-environment (architectural) Macro-environment (terrestrial)

winter heatingradiant

convected

summer conditions

cooled air dehumidified air

circulated air

winter humidity

household odors

view out

artificial illumination

productive sound

noise (waste sound)

inhabitants

nuclear radiation

winter insolation (infrared)

winter air temperature(still air)

winter winds

summer insolation

summer air temperature (still air)

summer breeze

summer humidity

precipitation

pleasant unpleasant

odors

dust and pollution

privacy (view in)

daylight

glare

artificial illumination

noise

visitors

intruders

vermin and insects

pollens

microorganisms

nuclear pollution

Thermal

Aqueous

Atmospheric

Luminous

Sonic

Biological

6.1

The building envelope

as selective filter,

adapted from James

Marston Fitch, 1948

75The Building Envelope As Selective Filter

exert on interior spaces. Examples of such iltering include the control of views into and out of a building, the transmission of natural light, the ventilation of interiors, and the regulation of rainwater. At the most basic level of performance, however, a curtain wall should be structurally sound. The com-ponents of the curtain wall system must be designed and built to resist anticipated loads, such as those induced by wind, seis-mic activity, and the potential impact of objects or people against the wall. The most signiicant load on a curtain wall is often lat-eral wind load (except in cases where blast resistance is required). The anticipated force of wind blowing against or pulling away from a curtain wall (the design wind load) is dependent on a number of factors: the location and orientation of the proposed building, the size and shape of the building, the immediate context of other structures or natural features, the surrounding land-scape, and the measured history of wind activity at the site. Sometimes the design wind load is speciied by local building code; often, however, it is calculated according to civil engineering principles or determined by testing a physical scale model of the pro-posed building in a wind tunnel. Wind loads on a single building may vary greatly in dif-ferent locations: higher wind loads are often present at the top of a building and at the corners of walls, as opposed to more cen-tralized areas. Due to orientation, one face or side of a building may see signiicantly higher or lower wind loads than other faces. Because the materials of the curtain wall tend to be relatively lexible and not rigid, delection (not strength) usually governs the resistance to wind. In other words, the curtain wall will likely reach an unaccept-able level of delection under wind loading before it will fail structurally. Therefore, most curtain wall speciications limit the allowable delection of the curtain wall mul-lions and inill panels to a certain dimension, based on the span of the member.

For example, vertical mullions spanning from one loor to the next are typically limited to a maximum delection of L/175, where L equals the loor-to-loor height.4 So, for a curtain wall spanning 10 feet (3 meters) vertically, the maximum allow-able delection of the mullion would be 10 feet/175 = 0.0571 feet, or roughly 5/8 inch.

Because of the continuous luctuation of

all environmental factors across time, the

building wall must be visualized not as a

simple barrier but rather as a selective,

permeable membrane with the capacity to

admit, reject and/or ilter any of these envi-

ronmental factors. All building walls have

always acted in this fashion, of course.

Modern scientiic knowledge and technical

competence merely make possible much

higher, more elegant and precise levels of

performance than previously.1

James Marston Fitch’s depiction of the building wall as a selective two-way ilter in American Building, irst published in 1948, remains a useful analogy, particularly given today’s growing concerns about energy efi-ciency and sustainability. Fitch envisioned the building envelope as analogous to the skin of the human body, which adaptively responds to the external environment in an effort to maintain optimal internal condi-tions. But the capacity of the human body to accommodate the range of climatic condi-tions evident in the natural world is of course limited, and we therefore require what Fitch termed an ameliorating “third element.”2 This third element, which he calls a “meso-environment,” acts as an interface between the microenvironment of the body and the macroenvironment of the external world. [6.1] There are two primary manifestations of the meso-environment: clothing and buildings. As Fitch explains, each can be tai-lored to meet the requirements of speciic people in particular situations (and, by the way, each may be subject to the whims of fashion). Clothing and buildings simply oper-ate at different scales: “One protects the individual only while the other shelters social processes as well.”3 The way in which the meso-environment, as the boundary between the micro and macro, modulates itself in response to changing conditions—its relative success or failure given speciied parameters and goals—may be considered its performance, and for contemporary cur-tain walls, performance is a key concept with important consequences for the way the system is designed and built.

The curtain wall should act as a selective ilter, purposefully controlling the low of heat, light, air, water, and sound, as well as the subsequent impact that these elements


performance, neutral low-E coating can attain a U-value as low as 0.29, as compared to 0.47 for uncoated insulating glass or 1.02 for uncoated monolithic (single-pane) glass.5 That same low-E unit can achieve a solar-heat-gain coeficient of 0.38, as compared to 0.70 for an uncoated unit, and it can be fur-ther improved through the use of tinted glass substrates.6 [6.3] Of course, most curtain walls are not entirely glass, and, in fact, the mullions that frame and support the glass are a potentially onerous source of unwanted heat transmission. The thermal break—a means of physically separating metal components that are exposed to the exterior from those exposed to the interior—is in certain climates an essential detail in a curtain wall mullion. In the design phase, architects may use thermal simulation software to test various conigura-tions of glass and mullions based on expected environmental conditions. [6.4]

In addition to specifying appropriate glass products and mullion conigurations, designers continue to experiment with mul-tilayered glass skins as a means of creating a more sophisticated selective ilter. The main concept in this type of system is the creation of an air plenum, between two lay-ers of glass, that acts as a moderating buffer between interior and exterior environmen-tal conditions. The two layers may be posi-tioned on either side of a single mullion, separated by several inches, or they may exist as two separately framed curtain walls, spaced several feet apart. In periods when interior heating is required, the air cavity remains sealed and the air is heated natu-rally by solar gain. This warmed air can then

[6.2] The curtain wall mullion in this case must be designed to resist the design wind load while delecting less than ive-eighths of an inch, a task that has implications for the material choice, the dimensions of the mullion itself, and the spacing of mullions on the facade. Higher wind loads may mean that mullions should be reinforced with steel or spaced closer together, or that a deeper mullion section is required.

As glass tends to dominate the contem-porary curtain wall, the overall thermal per-formance of the wall often comes down to the selection and detailing of the glass panel, which can be an inherently poor thermal insulator. The various glass treatments dis-cussed in the previous chapter can greatly affect the way that glass conducts heat and transmits or rejects solar energy. Relective and low-E coatings, consisting of microscopi-cally thin layers of metals deposited on the surface, signiicantly improve the shading coeficient and thermal insulating properties of glass. Obviously, the relective coatings popular in the 1970s acted basically as mir-rors, blocking unwanted solar energy from entering the building but also preventing the transmission of much visible light, thus elim-inating the transparency so long associated with glass. But a newer generation of special-ized metallic coatings, with improved perfor-mance, a more neutral appearance, and higher visible light transmittance, became available in the 1980s and 1990s. These coatings selec-tively ilter (transmit or relect) the various wavelengths of sunlight to ine-tune the facade’s performance. Currently, a double-pane clear insulating glass unit with a high-

10’

win

d p

ress

ure

maximum deflection

COMPARISON OF INSULATING GLASS PERFORMANCE

All examples assume 1/4"thick inner and outer glass panes with 1/2" air space

Clear glass, uncoated

Gray glass, uncoated

Clear glass with reflective coating

Clear glass with low-e coating

Gray glass with low-e coating

Clear glass with low-e coatingand ceramic frit pattern (50%)

Clear glass, uncoated, + argon fill

Clear glass, low-e + argon fill

Triple glazing, clear glass, uncoated

Triple glazing, clear glass low-e + argon fill

79%

41%

12%

70%

35%

44%

14%

7%

33%

11%

6%

22%

0.70

0.48

0.18

0.38

0.24

0.26

0.47

0.47

0.40

0.29

0.29

0.29

0.45

0.25

0.31

0.14

INSULATING GLASS TYPE

VISIBLE LIGHT TRANSMITTANCE

VISIBLE LIGHT REFLECTANCE SHGC

WINTERU-VALUE

6.2

Curtain wall deflection

diagram

6.3

Comparison of insulat-

ing glass performance

6.2 6.3


observed by the architect, owner, and con-tractor. The goal is to conirm the perfor-mance of the curtain wall with respect to a speciic set of criteria. The full-scale mock-up, usually about two stories in height and one or two structural bays in width, is built with the same materials and methods that will be used in the inal construction. It is subjected to a series of tests, which typically include resistance to air and water leakage, structural performance under wind load, and conden-sation resistance. A standard sequence may include the following:

1. Static Air Iniltration (ASTM E283): the

rate of air leakage through the curtain wall

2. Static Water Penetration (ASTM E331):

the amount of water leakage through the

curtain wall

3. Dynamic Water Penetration (AAMA 501):

water leakage under high wind conditions

4. Structural Performance (ASTM E330):

delection using air-pressure differential to

simulate wind load

5. Thermal Cycling (AAMA 501): simulates

the effects of temperature variation

6. Condensation Resistance (AAMA 1503):

assesses the likelihood of condensation

occurring within or on the curtain wall

7. Lateral and Interstory Movement

(AAMA 501): the mock-up frame is moved

laterally to simulate differential movement

of the building structure under wind or

seismic loads [6.5]

The mock-up’s response to each test is measured precisely and compared to the speciied criteria. If the model performs as

be used either as a passive buffer, which reduces the need for mechanical heating, or as preheated intake air for the HVAC system. During cooling periods, the air cav-ity can be ventilated to provide a continuous low of fresh air that can be routed into the interiors. The area between the layers of glass creates a convenient and protected location for sunshades, which can be adjusted seasonally or daily to provide the optimal balance of views and shading, blocking unwanted solar energy before it strikes the inner glass wall and making large expanses of glass more feasible from an energy stand-point. The multilayer approach also offers the beneit of improved sound control. While such active systems represent a major advantage over passive, single-skin precedents in meeting demands for both occupant comfort and energy eficiency, recent research suggests that the double skin is not technically superior to the less expensive alternative of reducing the amount of glass in the wall while increasing the area of opaque superinsulated wall.7 As architects and engineers continue to experiment with the active double wall and exploit its potential coordination and integra-tion with a building’s HVAC systems, it can be expected that further innovation will continue to yield better performance.

Regardless of the type of system chosen, it is common to subject a custom curtain wall to a series of physical mock-up tests to mea-sure its performance under simulated envi-ronmental conditions prior to inal installation on site. Such trials typically take place at a specialized independent laboratory and are

6.4

Thermal modeling of

curtain wall mullion, to

determine degree of

heat loss and suscepti-

bility to condensation

6.4


such as the adhesion of structural silicone, may be conducted in the factory during this period. Once on-site installation has begun, the curtain wall is subjected regularly to ield testing—standardized procedures that measure the amount of water and air inil-tration through the wall, as compared to speciied allowable amounts. Any problems found during such tests must be solved, with the remediation measures then applied similarly to all other areas of the wall.

There is an increasing expectation that architecture should respond intelligently to local climatic conditions, conserving rather than wasting resources, and that it should achieve, as Fitch described, “much higher, more elegant and precise levels of perfor-mance.” As the primary interface between the exterior macroenvironment and the interior meso-environment, the building envelope has an essential role to play in this pursuit. The achievement of a high-performance curtain wall, moving beyond the status quo, relies on the expertise of the design team, the clear delineation of performance parameters and criteria, an intense process of testing and inspection, and a spirit of experimentation and technological innovation.

expected, it passes; otherwise, remediation measures are required, and the system must be modiied so that it can pass a retest. The process, though costly in terms of money and time, is a valuable tool, particularly for custom systems. Potential problems in performance and aesthetics can be identiied well in advance of on-site installation, giving the design team and the fabricator an opportunity to resolve ificulties and to more fully ensure a successful installation phase and inal product.

The performance of a curtain wall is inlu-enced equally by the quality of its design and construction. An inadequately designed cur-tain wall will likely fail, even if it is fabricated and installed well; a well-designed curtain wall may fail if it is fabricated and installed poorly. For these reasons, the curtain wall design process begins with extensive com-ponent research, engineering, detailing, and preliminary testing, and continues onto the construction site with a battery of ield tests and inspections to ensure proper performance of the wall, once it is installed. During pre-fabrication of a unit system, for instance, it is common for the design team to periodi-cally visit the factory to inspect progress on the curtain wall. Testing the components,

6.5

Airplane engine and

propeller used to

simulate high winds

during a curtain wall

mock-up test

6.5


Endnotes

1 James Marston Fitch, American Building:

The Environmental Forces That Shape It (Boston: Houghton Miflin, 1972), 9. First published in 1948.

2 Ibid., 8.3 Ibid., 9.4 L/175 is an industry standard, although some

architects prefer a more stringent limitation of L/240. Also, the maximum delection of a cur-tain wall mullion is often limited to L/175 or 3/4 inch (1.9 centimeters), whichever is less, as 3/4 inch is considered the highest acceptable delection of a typical mullion, regardless of load.

5 The U-value is a measure of heat gain or loss through glass due to differences between indoor and outdoor temperatures; it measures the insulating value of glass. The lower the U-value, the better the insulating performance. The U-value unit is BTU/(hr × ft2 × ̊ F) or in metric W/(m2 × ˚K).

6 The solar heat gain coeficient (SHGC) of glass measures the portion of directly transmitted and absorbed solar energy that enters into the building’s interior. A higher SHGC indicates more heat gain.

7 See John Straube, “A Critical Review of the Use of Double Facades for Ofice Buildings in Cool Humid Climates,” Journal of Building Enclosure

Design (Winter 2007): 48–52.

Part III:Case Studies

The following case studies present twenty-four recently constructed buildings with

innovative curtain walls. The selected projects are geographically diverse and range in

scale from two to fifty-two stories tall. They encompass a broad range of building types:

museums, libraries, office buildings, educational and research centers, residential tow-

ers, government buildings, and religious institutions.

Although the curtain wall design of each building is unique, there are broad themes

that many of the projects share. Several curtain walls address performance issues

through multiple layering, with double-skin walls, external shading devices, and opera-

ble components. Some projects illustrate the challenges of designing a curtain wall for a

geometrically complex building form. In several projects, there is a clear desire to break

away from the traditional vertical plane by introducing angled facades and tilted glass.

Some buildings exploit the potential of unusual curtain wall materials, such as wood and

translucent stone, while others employ standard materials in novel ways: the glass, for

instance, is tinted, silkscreened with custom patterns, or formed into channel shapes.

Kenneth Frampton writes:

The full tectonic potential of any building stems from its capacity to articulate both the

poetic and the cognitive aspects of its substance….Thus the tectonic stands in opposi-

tion to the current tendency to deprecate detailing in favor of the overall image.1

The buildings chosen for this study embody this duality of poetic design and tech-

nical, detail-oriented rigor. Each of these buildings engages in image-making, clearly

seeking to create a distinctive visual impact, but they equally pursue experiential and

performance-driven objectives, illustrating the depth of technical knowledge of mate-

rials and fabrication methodologies required for successful innovation in curtain wall

design and construction. In addition to photographs and general building information,

the tectonic character of each curtain wall is represented on the following pages with a

detailed elevation-plan-section composite drawing that delineates system components,

materials, key dimensions, and the relationship between wall and building structure.

1 Kenneth Frampton, Studies in Tectonic Culture (Cambridge, Mass.: MIT Press, 1995), 26.

Introduction

Case Study Title 84

Skirkanich Hall / p.162

Torre Cube / p.148

Torre Agbar / p.140

One Omotesando / p.100

Green-Wood Mausoleum / p.112

Netherlands Institute for Sound and Vision / p.154

Melvin J. and Claire Levine Hall / p.94

Terrence Donnelly Centre for Cellular

and Bimolecular Research / p.132

LVMH Osaka / p.118

Seattle Public Library / p.126

William J. Clinton

Presidential Center / p.106

The New 42ndd Street

Studios/ p.86

Case Study Title 85

166 Perry Street / p.250

100 Eleventh Avenue / p.244

Cathedral of Christ the Light / p.236

Yale Sculpture Building / p.230

United States

Federal Building / p.222

Nelson-Atkins Museum of Art / p.198

Biomedical Science Research Building / p.176

The New York Times

Building / p.206

ATLAS Building / p.184

Trutec Building / p.168

Blue Tower / p.190

Spertus Institute of

Jewish Studies / p.214

Case Study Title 86

Case Study Title 87

The New 42nd Street Studios New York, NY United States

Curtain Wall

Stick system with extruded-aluminum

mullions and low-E coated insulating glass

units; on the south facade, an external layer

of perforated stainless-steel louver blades

set within an armature of painted steel

Program

A total of 84,000 square feet

(approximately 7,804 square meters)

of space, including fourteen rehearsal

studios for music, dance, and theater;

office space for performing-arts groups;

a 199-seat experimental theater; and

ground-floor retail

Architect


Client

New 42nd Street, Inc.

Curtain Wall Consultant

Heitmann and Associates

Structural Engineer

Anastos Engineering Associates

MEP Engineer

Goldman Copeland Associates

Exterior Lighting Designer

Vortex Lighting (Anne Militello)

Completion Date

2000

88Part III: Case Studies

Located in New York City’s Times Square

Theater District, this ten-story tower

serves as the headquarters for the non-

profit arts group New 42nd Street. It was

built as part of a major redevelopment

plan to transform the block through the

revitalization of existing theaters and an

infusion of new commercial and arts-related

initiatives. The public face of the building

is the south facade, where the curtain wall

is conceived as a multilayered and multi-

functional system of enclosure. Cantile-

vered floor slabs support a continuous

glass-and-aluminum curtain wall, provid-

ing a floor-to-ceiling glass envelope at

each level. By day, the building’s offices

and rehearsal spaces are flooded with

natural light, diffused through an outer

layer of perforated stainless-steel louvers

that start about 6 feet (1.8 meters) above

each floor and extend upward to the next

level. A grid of painted steel framing

members support the louvers, which are

held approximately 3 feet (0.9 meters) in

front of the glass wall on horizontal steel

outriggers anchored to each floor slab.

The curtain wall also incorporates adjust-

able translucent shades for glare control,

operable windows for natural ventilation,

and an exterior maintenance catwalk.

The redevelopment guidelines for 42nd

Street required a significant amount of

exterior lighting and signage to maintain

the character of the district. In response,

Platt Byard Dovell White—working with

lighting designer Anne Militello of Vortex

Lighting—transformed the south facade

into a building-scale luminaire, or complete

lighting unit. The stainless-steel louvers act

as a canvas onto which a nightly computer-

controlled light show is projected, turning

the facade into a shimmering, abstract

collage of color. This use of integrated

architectural illumination offered an alter-

native to the advertising-dominated

theme-park feel that pervades the district.

1

Typical floor plan

2

South elevation

1 2

89The New 42nd Street Studios

3

4

3

Detail of nighttime

illumination

4

Exterior view, from

southeast


5

Partial elevation

5' 6" (1.52 m)

6

Plan


7

Section

17'

4"

(5.2

8 m

)

Perforated ground

stainless-steel blades

Painted steel

vertical strut

Steel-grate mainte-

nance catwalk on

steel outrigger

Exterior light fixtures


low-E coating

Out-swinging

operable window

Extruded-aluminum

mullion

Adjustable

translucent shade

Raised dance floor

on concrete slab

Cantilevered steel

beam

I

H

G

FA

B

C

D

E J

A

B

C D

E

F

G

I

H

J


8


8

Multilayered facade

components

9

View of upper floors,

from southwest

10

Detail of southeast

corner

11

Interior view of curtain

wall in dance studio

9

10

11

Case Study Title 94

Case Study Title 95

Melvin J. and Claire Levine HallPhiladelphia, PA United States

Curtain wall

Custom active double-skin unit system

with prefabricated extruded-aluminum

unit frames, external double-pane

insulating glass, and internal single-

pane glass

Program

Offices, laboratories, meeting spaces,

and an auditorium for the Department

of Computer and Information Science

at the University of Pennsylvania

Architect


Client

University of Pennsylvania School of

Engineering and Applied Science

Structural Engineer

CVM Structural Engineers

Civil Engineer

Barton and Martin Engineers

MEP Engineer

Vanderweil Engineers

Energy Consultant

Arup

Completion Date

2001


Melvin J. and Claire Levine Hall is one of

the first large-scale applications of an active

double-wall concept in the United States.

A desire for transparency and openness—

a counterpoint to the masonry aesthetic

of the surrounding campus—led to the

design of an all-glass curtain wall. To avoid

the use of dark-tinted or reflective glass and

large areas of spandrel, as would normally

be required by the energy code, Kieran-

Timberlake researched the potential of

using an active double-skin to maintain

transparency and mitigate thermal issues

inherent in conventional single-skin

curtain walls.

The final design called for a custom unit

system incorporating various configurations

of extruded-aluminum frames with two

layers of glass: an outer double-pane insu-

lating unit and a single inner pane. The two

layers are separated by a 6-inch (15-

centimeter) plenum, through which air

circulates; it is preheated by the sun (in win-

ter) before being transferred to the HVAC

system. The air cavity houses electronically

controlled blinds to reduce heat gain in

summer. The fully prefabricated unit system

was installed on site in seven weeks. Credit

must also go to the client, the University

of Pennsylvania, for recognizing the benefits

of an unusually high-performance, energy-

efficient building envelope and for under-

standing that the higher construction

cost of such a system would be balanced

by lower energy use and operating costs

over the life of the building.

1

View through

curtain wall,

from interior

2

View of interior

1 2

97Melvin J. and Claire Levine Hall

Qty. 8

Qty. 8

Qty. 11 Qty. 4 Qty. 3 Qty. 3 Qty. 3 Qty. 3

Qty. 7 Qty. 9 Qty. 19 Qty. 7 Qty. 7

Qty. 1 Qty. 10 Qty. 1 Qty. 9 Qty. 1

3 4

5

3

Installation of curtain

wall units

4

View of west elevation

5

Catalog of custom

curtain wall unit types

A1A

A4

B6 B6A B6B B7 B8 B9

A5 B1 B2 B4 B5

A1A A2 A2A A3 A3A


6

Partial elevation

7

Plan

7' (2.13 m) 4' 4" (1.32 m)

99Melvin J. and Claire Levine Hall

8

SectionOuter skin: clear insu-

lating glass with low-E

coating

Inner skin: monolithic

glass (sandblasted in

some areas)

Adjustable interior

cavity blind (electronic)

Adjustable room shade

(manual)

Exhaust air duct (from

curtain wall cavity)

Extruded-aluminum

unit frame

Finished floor on rein-

forced concrete slab

Fire-safe insulation

at slab edge

Suspended ceilingI

H

G

F

A

B

C

D

E

A B

C

D

E

H

I

G

F

14'

(4.2

7 m

)

Case Study Title 100


One OmotesandoTokyo, Japan

Curtain Wall

Custom stick system incorporating

monolithic glass and external vertical

wood fins

Program

A total of 83,000 square feet (4,459

square meters) of office and retail

space for a fashion company

Architect


Client

LVMH

Structural Engineer

Oak Structural Design Office

Mechanical Engineer

P. T. Morimura and Associates

Completion Date

2003

Part III: Case Studies 102

This seven-story building stands at the

entrance to Omotesando Avenue. Lined

on both sides with tall Zelkova trees, the

avenue leads to the city’s oldest Shinto

shrine, the Meiji Shrine. The architect

sought to design a building that would

reflect the natural warmth of surrounding

greenery and reference Japan’s long

tradition of building with wood.

The curtain wall is constructed out of

extruded-aluminum mullions that span ver-

tically from floor to floor and support the

monolithic tempered glass. Horizontal

joints between glass panels are minimized

through the use of structural silicone glaz-

ing, while the vertical joints are emphasized

with protruding tapered fins of laminated

wood (Japanese Larch) attached to each

vertical mullion. These fins, measuring

approximately 18 inches (0.5 meters) deep,

act to stiffen the vertical mullions and lend

an unusual texture and color to the curtain

wall. Additionally, the fins act as solar-shad-

ing devices, reducing the amount of direct

sunlight that reaches the floor-to-ceiling

glass panels. Because of fire-safety con-

cerns, Tokyo’s building code prohibits the

use of wood on exterior walls in dense

urban areas; however, the fins were permit-

ted due to the unusual provision of water

sprinkler heads spaced at regular intervals

along the exterior surface of the curtain wall.

1

View from

Omotesando

Avenue

1

2

View from interior

3

Detail of wood

fin attachment at

curtain wall

4

Exterior view

103One Omotesando

2

3

4


5

Partial elevation

6

Plan

2' (0.60 m)

105One Omotesando

7

SectionLaminated wood fin

Monolithic tempered

glass

Extruded-aluminum

mullion

Glass soffit

Adjustable shade

Raised floor on

concrete slab

Suspended ceilingG

F

A

B

C

D

E

A

B

C

DE

F

G

13'

9"

(4.2

m)


William J. Clinton Presidential CenterLittle Rock, AK United States

Curtain Wall

The primary, west-facing curtain wall:

a custom double-layered stick system with

an inner curtain wall of low-iron insulating

glass supported by steel-tube framing,

with an outer skin of point-supported

laminated glass with a printed interlayer

Program

A presidential library with permanent and

temporary exhibition spaces, an education

and media center, an event space, a cafe,

and a rooftop residential apartment

Architect


Client

William J. Clinton Presidential Center

Associate Architects

Polk Stanley Rowland Curzon Porter

Architects; Witsell Evans Rasco Architects;

Woods Caradine Architects


R. A. Heintges and Associates

Structural Engineer

Leslie E. Robertson Associates

MEP Engineers

Flack and Kurtz; Cromwell Architects

Engineers

LEED Consultants

Steven Winter Associates; Rocky Mountain

Institute

Completion Date

2004


The William J. Clinton Presidential Center

is located in a public park along the south

bank of the Arkansas River and within

walking distance of downtown. The bulk

of the 165,000-square-foot (15,329-square-

meter) building is elevated in a linear

form, cantilevered toward the river and

supported by massive exposed-steel

trusses, inspired by an adjacent century-

old railroad bridge. Unusual among presi-

dential libraries, the design embraces

modern aesthetics and technology and

offers a contemporary approach to the

articulation of architecture, which is per-

haps most apparent in the design of

the exterior envelope.

The client’s objectives included an open

and accessible museum and a commitment

to environmental responsibility; the building

earned a LEED Silver certification. The main

facade is the west elevation, which faces

toward an entry plaza, with downtown Little

Rock visible in the distance. The curtain wall

consists primarily of transparent glass, which

allows for expansive views and natural light-

ing. At night, activities within the center are

on display through the glass walls.

The double-height curtain wall at the

exhibition wing is composed of two walls of

glass on either side of a porchlike space

measuring 10 feet (3 meters) deep. The inner

wall of low-iron, low-E coated insulating

glass forms the true weather envelope of the

building, while an outer rainscreen of lami-

nated glass provides solar protection and

sound insulation. The glass of the inner wall is

framed by extruded-aluminum glazing adapt-

ers mounted to horizontal steel tubes sus-

pended, by steel tension cables, from the roof.

The glass of the outer wall is laminated with

an interlayer of custom-printed, thin black-

and-white lines that allow views through while

deflecting a portion of the solar energy strik-

ing the surface. Countersunk stainless-steel

point fittings (or spiders) support the glass

panels at each corner and are, in turn, sup-

ported by horizontal steel tubes that are sus-

pended from above, similar to the inner wall.

1

Floor plan,

level four

2

East-west section,

looking south

1

2

109William J. Clinton Presidential Center

3 4

5

3

South elevation

4

View from south

5

Space between

outer and inner

glass walls, looking

north toward

the river


6

Partial elevation

7

Plan

10' (3.05 m)

111William J. Clinton Presidential Center

8

Section Laminated low-iron

tempered glass

Countersunk stainless-

steel bolt and spider

fitting

Painted steel tube

Stainless-steel threaded

dead-load rod

Steel column

Laminated low-iron

insulating glass with

low-E coating

Steel and aluminum

mullion with stainless-

steel cladding

Steel truss

Tempered glass

railing

Adjustable shades

G

H

I

J

FA

B

C

D

E

A

B

C

D

DE F

G

H

I

J

5' 4

" (1

.63

m)


Green-Wood MausoleumBrooklyn, NY United States

Curtain Wall

Custom hybrid system of preglazed units

mounted in a shinglelike configuration

onto steel mullions

Program

A new mausoleum facility providing

burial chambers and gathering spaces

within Green-Wood Cemetery

Architect


Client

Green-Wood Cemetery

Structural Engineers

Siracuse Engineers; Leslie E. Robertson

Associates

MEP Engineer

Joseph R. Loring and Associates

Completion Date

2004


Established in 1838, Green-Wood Cemetery

was designated as a National Historic

Landmark in 2006. The new five-story mau-

soleum provides 2,000 additional burial

chambers. The design is based on a

strong yet simple dichotomy of solidity

and lightness. The crypts are organized

into three vertical stacks encased in stone-

clad walls; these massive volumes are

earthbound, cut into the steep hillside,

and they are organized around two sky-lit

atria containing stairs and seating areas.

The rear wall of each atrium is formed by

a four-story interior waterfall, which is

echoed at the front in a cascading glass

curtain wall that provides abundant natu-

ral light and views of the landscape.

The fluidity, openness, and airiness of

the atriums balance the heaviness of the

burial chambers.

The glass curtain wall is composed of

a custom system of monolithic clear glass

panels angled, in section, like shingles,

with the lower edge of each panel cantile-

vering several inches beyond the frame.

Structural silicone sealant holds the glass

in place and minimizes the external

expression of the supporting framework.

The glass is preglazed onto extruded-

aluminum frames, which are then anchored

to an internal framework of exposed hori-

zontal and vertical steel mullions suspended

from each floor slab. The exposed, free-

floating edges and precise detailing of

the panels contribute to the overall

sense of lightness.

1

Southeast elevation

2

Cantilevered

monolithic glass

21

115Green-Wood Mausoleum

3

4

3

Interior view of

curtain wall at

top floor

4

Typical floor plan


5

Partial elevation

6

Plan

7' 5" (2.26 m)

117Green-Wood Mausoleum

7

Section Structurally glazed

monolithic tempered

glass

Extruded-aluminum

unit frame

Painted steel beam

Painted steel column

Painted steel guardrail

Reinforced-concrete

floor slab

F

A

B

C

D

E

A

B CD

E

F

4'

6"

(1.3

7 m

)


LVMH OsakaOsaka, Japan

Curtain Wall

Hybrid system with floor-to-floor

translucent panels of laminated

stone and glass preglazed to extruded-

aluminum frames and mounted onto

vertical steel mullions

Program

Ninety-thousand square feet (8,361

square meters) of office and retail space

for a fashion company

Architect


Client

LVMH Japan Group


Front

Structural Engineer

Ban Design Studio

Mechanical Engineer

P. T. Morimura and Associates

Completion Date

2004


Kengo Kuma and Associates’ nine-story

LVMH building in Osaka, Japan, presents

a building envelope of remarkable material

effect; an intentional blurring of the tradi-

tional distinction between wall and window,

and between stone and glass. From day

to night, the curtain wall continually shifts

conditions, from opacity to transparency

and translucency.

The curtain wall incorporates 5/³²-inch-

thick (4 millimeters) onyx slabs laminated

between sheets of clear glass. These slices

of stone are thin enough to transmit dif-

fused light. During the day, they appear

solid and opaque from the exterior, while

allowing natural light to filter through to

the interior; at night, the stone panels glow

from within, revealing their translucent

nature, thanks to fluorescent cove light

fixtures integrated into each mullion.

The monolithic stone cube transforms into

a lantern. To provide opportunities for

views through the curtain wall, the stone-

and-glass composite panels alternate, in

a ratio of two to one, with laminated glass

units utilizing a polyester interlayer printed

with a pattern that resembles the grain of

onyx. While the panels simulate the texture

and color of the stone, they are primarily

transparent. Both types of glass panels

extend vertically from floor to floor—with-

out spandrels—and are preglazed onto

minimal frames of extruded aluminum,

which are, in turn, mounted onto vertical

mullions of built-up steel.

1

1

Section

2

Typical floor plan

2

121LVMH

3 + 4

Interior views

4

3


5

Partial elevation

6

Plan

3' (0.91 m)

123LVMH

7

Section Laminated panel:

glass, translucent

stone, glass

Laminated glass with

printed interlayer

Extruded-aluminum

frame

Vertical steel mullions

with integral light

fixture

Adjustable blinds

Raised floor on

concrete slab

Fireproofed steel

beam

Suspended ceiling

F

G

H

A

B

C

D

E

AD

E

F

G

H

B

B

C

2 f

t. 1

1 in

. (0

.89 m

)

13'

2"

(4 m

)


8

Night view

8

125LVMH

9

Curtain wall parapet

10

View from street

9

10


Seattle Public LibrarySeattle, WA United States

Curtain Wall

Custom stick system of steel and

aluminum framing members arranged

in a diamond-grid configuration

supporting low-E coated, laminated

insulating glass.

Program

Seattle’s central public library containing

book stacks, reading rooms, meeting

rooms, a children’s center, administrative

offices, an auditorium, and parking

Architects

Office for Metropolitan Architecture

(OMA); LMN Architects

Client

Seattle Public Library

Facade Consultants

Dewhurst Macfarlane and Partners;

Front


Arup; Magnusson Klemencic Associates

MEP Engineer

Arup

Civil Engineer

Magnusson Klemencic Associates

Completion Date

2004


Sited within the dense urban context of

downtown Seattle, the 412,000-square-

foot (38,276-square-meter) Central Library

owes its aggressively distinctive character

to two defining design moves: the stack-

ing and shifting of building masses into an

unexpected prismatic form, and a custom

curtain wall system that wraps continuously

around all sides of the building.

The curtain wall is composed of diamond-

shaped panels of insulating glass, measur-

ing approximately 4 feet (1.2 meters) per

side, set within a diagrid framework of steel

and aluminum. As the primary cladding of

the building, the glass units were designed

for high performance and include a lami-

nated pane for safety and UV protection; a

low-E coating; krypton gas fill for increased

thermal performance; and, in areas of the

building subject to intense summer sun,

an expanded aluminum mesh interlayer,

which acts as a system of micro louvers to

reduce solar heat gain while maintaining

views. The glass is supported by extruded-

aluminum glazing adapters attached either

to seismic structural-steel framing mem-

bers (on sloped faces) or to I-beam-shaped

mullions of extruded aluminum (on vertical

faces). It is held in place by exterior alumi-

num glazing caps. The building skin con-

tributes not only to the exterior character

of the building—signaling a willingness to

forego traditional concepts of library archi-

tecture—but also to the interior experience

of the end users, who encounter the diagrid

enclosure from different vantage points

throughout the eleven-story building.

In recognition of the complexity and

overall importance of the building enve-

lope, an early bid package and contractor

selection process for the curtain wall

allowed the architects to collaborate with

the curtain wall manufacturer (the German

firm Seele) throughout the design and

construction phases, ensuring that

architectural design goals and stringent

performance criteria were met.

1

Unfolded elevation

2

Locations of glass

with metal mesh

interlayer

1

2

129Seattle Public Library

3

Southwest corner

4

Third-floor interior

5

Interior view from

fourth floor

6

Interior view of

curtain wall mounted

on seismic steel

framing

3

4

5 6


7

Partial elevation

8

Plan

131Seattle Public Library

8

Section Laminated insulating

glass with low-E

coating, argon fill,

and mesh interlayer

Extruded-aluminum

glazing adapter

Extruded-aluminum

diagonal mullion

Structural steel

Formed aluminum

gutter with stainless-

steel snow fence and

drain

Raised floor

Concrete slab on

deck

F

G

A

B

C

D

E

A

B

C

D

EF

G

16

' 5

" (5

m)

Case Study 132

Case Study 133

Terrence Donnelly Centre for Cellular and Biomolecular Research Toronto, Ontario Canada

Curtain Wall

The south facade: a double-skin glass

curtain wall, with an outer layer of monolithic

glass and an inner layer of insulating glass,

each framed by extruded-aluminum

mullions and separated by an air space

Program

A human genome research facility with

laboratories, offices, and common spaces,

including multistory interior gardens

Architects

architectsAlliance; Behnisch Architekten

Structural Engineer

Yolles Partnership

Mechanical/Electrical Engineer

HH Angus & Associates

Completion Date

2005


The twelve-story Terrence Donnelly Centre

for Cellular and Biomolecular Research,

located at the University of Toronto’s

St. George campus, is a high-performance

building that achieves impressive levels

of energy efficiency and—with airy, light-

filled spaces throughout—attention to

occupant comfort. The building responds

intelligently to its climate and orientation

with an enclosure system that presents an

open face to the campus and adapts to

changing environmental conditions. At the

same time, it strikes a balance between auto-

mated and individually controlled devices.

The 248,000-square-foot (23,039-square-

meter) research facility is organized with

laboratories to the east, circulation to the

west, and principal researchers’ offices

to the south, facing a landscaped entry

plaza. It is this south-facing wall that is the

most technologically innovative. Offices

here are enclosed with a double-skin glass

curtain wall, framed by extruded-alumi-

num mullions, that provides a high degree

of acoustic, solar, and thermal control.

The outer skin of monolithic glass is sepa-

rated from the inner layer of insulating

glass by an air space of 2.5 feet (0.8 meters),

containing retractable perforated alumi-

num sunshade louvers to reduce solar

heat gain and redirect daylight into the

building. The outer skin incorporates

operable louvers at the top and bottom

to ventilate the cavity, while the inner

wall has operable windows to naturally

ventilate the offices.

In winter the air cavity remains sealed,

as the sun naturally heats the air to create

a buffer between the interior and exterior;

in summer the cavity is freely ventilated.

A computerized building system automat-

ically adjusts the sunshades for optimal

solar protection, although each individual

occupant may override the system, as

desired. Likewise, occupants can control

the degree of ventilation in each office.

When a window is opened, a sensor auto-

matically switches off the heating and cool-

ing supply to that space, thereby increasing

energy efficiency and avoiding waste.

21

135Terrence Donnelly Centre for Cellular and Biomolecular Research

1

Tenth-floor

plan

2

View from

southwest

3

Double-skin

curtain wall

4

Southwest

corner

5

Interior view

3

5

4

4

Interior view


6

Partial elevation

7

Plan

4' (1.22 m)


8

Section Monolithic

tempered glass

Stainless-steel

patch fitting

Mechanical

ventilation damper

Laminated tempered

glass floor

Steel outrigger

Automated blinds

Insulating glass in

extruded-aluminum

unit frame

Aluminum spandrel

with insulation

Finished floor

over cantilevered

concrete slab

Suspended ceiling

G

H

I

J

A

B

C

D

E

F

A

B

C D

E

F

G

H

I

J

13' 4

" (4

.06 m

)


9

West elevation

at night

Case Study 140

Case Study 141

Torre AgbarBarcelona, Spain

Curtain Wall

Custom system of clear and translucent

glass louvers suspended on extruded-

aluminum framing members, in front of

a load-bearing reinforced-concrete wall

with punched windows

Program

Office headquarters for a local water

company

Architect


Client

Layetana Inmuebles S.L.

Facade Consultants

Xavier Ferres (Biosca Botey); Alain Bony;

Arnauld de Bussierre


R. Brufau; A. Obiol

MEP Engineer

Gepro

Lighting Consultant

Yann Kersalé

Completion Date

2005


Housing the headquarters of Barcelona’s

water utility, Torre Agbar is a thirty-one-story,

bullet-shaped tower sited within a new

commercial development in Plaça Glòries.

Jean Nouvel’s design was conceived as

an expression of the fluidity of water and

its interaction with light. The architect likens

the exterior to an enormous geyser of

water under continuous pressure.

In stark contrast to the popular formula-

tion of the skyscraper as a glass-clad,

steel- framed box, Torre Agbar employs

a reinforced- concrete bearing-wall struc-

ture, defined in plan and section by gentle

curves pierced with 4,500 individual window

openings. The bearing wall, which in

conjunction with an internal structural core

ensures a column-free interior, ranges in

thickness from 19 inches (0.5 meters) at the

base to twelve inches at the twenty-ninth

floor, where it ends; the upper six floors

are framed in steel and clad in glass.

The exterior of the bearing wall is divided

into a continuous 1-square-meter (10.8-

square-foot) grid covered in insulation and

corrugated aluminum panels painted

various shades of red, blue, green, yellow,

and white. An apparently random pattern

of punched openings in the wall provides

views, daylight, and natural ventilation,

incorporating insulating glass in extruded-

aluminum window frames. The bearing

wall is encased in a continuous external

skin of clear and translucent laminated

safety-glass louvers set at various angles.

These louvers are mounted on vertical

rails of anodized extruded aluminum that

are suspended from the concrete wall

on aluminum brackets at each floor level.

As compared to other all-glass curtain

walls, the combination of louvers, a thick

external wall, and a high ratio of solid wall

to window create a more energy-efficient

building. The result of this unique building-

envelope system is an intriguing surface

effect that is not merely a thin surface in

the normal sense, but a multilayered

surface that has a literal and metaphorical

depth unlike any other skyscraper in

Barcelona or elsewhere.

1

Typical floor plan

2

Exterior detail 2

1

143Torre Agbar

3

Unrolled elevation

4

Exterior night

view

5

Exterior daytime

view

4 5

3


6

Partial elevation

7

Plan

6' 6" (2.0 m)

145Torre Agbar

8

Section Laminated glass louver

Anodized extruded-

aluminum rail

Aluminum window

with low-E coated

insulating glass

Painted corrugated

aluminum sheet

Mineral wool insulation

over reinforced-

concrete wall

Galvanized-steel

maintenance catwalk

Raised floor

Concrete slab on

metal deck and

steel beam

Suspended ceiling

F

G

H

I

A

A B

C

D

E

F

B

C

D

E

G

H

I

12'

2"

(3.7

m)


9

147Torre Agbar

10

11

12

9

Interior views

10

Detail of louvers

11

Installation of

windows

12

Exterior view

at midlevel

Case Study 148

Case Study 149

Torre Cube Guadalajara, Mexico

Curtain Wall

Window walls with extruded-aluminum

framing and floor-to-ceiling monolithic

glass protected by a brise-soleil system

of timber slats

Program

Leasable office space with underground

parking

Architect

Estudio Carme Pinós

Client

Cube International

Structural Engineer

Luis Bozzo

Completion Date

2005


Sited in a dense office building develop-

ment, Torre Cube stands out among its

neighbors for its distinctive massing and

material expression. The building houses

approximately 50,000 square feet (4,645

square meters) of space on sixteen levels

and is organized around a central atrium

that is open to the sky. Three massive con-

crete cores—containing vertical circula-

tion, service spaces, and ductwork—form

the main vertical structure of the building.

From these cores, steel girders are

cantilevered to support the column-free

offices, which feature floor-to-ceiling glaz-

ing on three sides. The glass is contained

within frames of extruded aluminum, span-

ning between the floor slabs. A system

of external brise-soleil panels protects the

building from excessive heat gain. They

are composed of heat-treated pine slats,

set in frames of welded steel that are sus-

pended two feet in front of the glass wall

(with a maintenance catwalk in-between).

The varied spacing and natural color

variation of the wood slats give the facade

an organic warmth that is unusual for

office-building construction. Some of the

eye-level brise-soleil panels slide aside

on tracks, allowing for unimpeded views

and increased daylighting when desired.

Sliding glass doors within the window wall

provide access to the brise-soleil panels

and allow natural ventilation in the offices.

Additionally, on each side of the building

and at different heights, three floors of

office modules are eliminated to create

exterior plazas and promote the free circu-

lation of fresh air into the atrium. Because

of these measures, and the mild climate

of Guadalajara, no air-conditioning is

required in the offices.

1

Section

2

Typical floor

plan

12

151Torre Cube

3 4

5

3

Wood screen at

east elevation

4

View from

southeast

5

Construction

sequence


6

Partial elevation

7

Plan

5' 5" (1.65 m)

153Torre Cube

8

Section Heat-treated pine strip

on steel angle frame

Vertical steel-pipe

bracing

Guide track and rollers

for sliding screen

Tempered monolithic

glass in extruded-alumi-

num frame

Maintenance catwalk:

galvanized-steel grating

Steel pipe

Steel outrigger

Embedded steel

anchor plate at

slab edge

Raised floor on

concrete slab

Suspended ceiling

F

G

H

I

J

A

B

C

D

E

AB

C D

E

F

G

H

I

11'

6"

(3.5

m)

J

Case Study 154

Case Study 155

Netherlands Institute for Sound and Vision Hilversum, the Netherlands

Curtain Wall

Custom double-layer wall with a

continuous outer screen of textured,

color-stained glass panels bearing

abstracted scenes from Dutch television

Program

A 323,000-square-foot (30,007-square-

meter) media museum with interactive

exhibition spaces, a public atrium, archives,

offices, a museum store, workshops,

a cafe, and underground parking

Architect

Neutelings Riedijk Architects

Client

Netherlands Institute for Sound and Vision

Facade Consultant

Jaap Drupsteen

Structural Engineer

Aronsohn Raadgevende

Building Physics

Cauberg-Huygen Raadgevende

Completion Date

2006


Three main program elements constitute the

Netherlands Institute for Sound and Vision:

a series of galleries for interactive media

exhibitions, a block of administrative offices,

and the national archives of Dutch radio

and television. These spaces are grouped

around a central atrium that extends from

the front to the rear of the building and

from the lowest floor to the skylit roof.

In a unique twist on the modernist ideal

of a facade expressing the inner function of

the building, the outer skin of the institute

consists of a composition of glass panels

imprinted with 748 specific images, or still

frames, from Dutch television programs,

selected from the national archives (housed

inside and presumably in the collective mem-

ory of the TV-watching public). The images

are mostly abstracted through a blurring

effect; the exact scenes are not immedi-

ately apparent, although many are discern-

ible. The architects worked collaboratively

with the graphic designer Jaap Drupsteen

and the glass manufacturer Saint-Gobain

to develop a method of transferring the

selected film stills onto glass by CNC-

milling them onto a wood panel, which

was then used as a mold onto which the

glass, along with colored ceramic paste,

were placed and then heated. This process

imparts the colored, textured image in

relief onto the glass.

These tempered-glass panels, measuring

.375 inches (1 centimeter) thick, are used

to clad all four sides of the building. They

are typically glazed on two sides (top

and bottom) to steel channels, which are

anchored to continuous horizontal steel

tubes. The tubes are suspended from the

roof above by vertical steel rods. The inner

wall varies from clear insulating glass to a

solid, opaque wall. At the office wing, the

inner wall alternates between steel-framed

insulating glass windows and precast-

concrete wall panels faced with insulation

and fiber-cement sheeting. In these areas,

the colored outer glass is replaced in

every third bay with clear glass to provide

unimpeded views from the offices.

1

Section

2

Textured-glass

panel at west

elevation

3

East elevation

4

Interior view at

atrium

1

157Netherlands Institute for Sound and Vision

2

43


5

Partial elevation

6

Plan

3' 11" (1.2 m)


7

Section Custom-patterned

cast glass in pivoting

steel frame

Clear tempered glass

at operable vent

Steel suspension rod

Steel tube

Insulating glass in

thermally broken

steel frame

Steel tube column

Cement-fiber panel

over mineral-fiber

insulation

Precast-concrete

wall panel

Finished floor on

concrete slab

F

G

H

I

A

B

C

D

E

A

B

D

F

G

H

I

10' 5"

(3.1

6 m

)

E

C


8

West elevation

at night

9

Southeast corner

10

Detail of textured-

glass panel

8


10

9

Case Study 162

Case Study 163

Skirkanich Hall Philadelphia, PA United States

Curtain Wall

Customized thermally broken stick

system with angled mullions of

extruded aluminum supporting clear

and translucent glass panels

Program

Research and instructional laboratories

and office space for the School of

Engineering and Applied Sciences

at the University of Pennsylvania

Architect

Tod Williams Billie Tsien Architects

Client

University of Pennsylvania School of

Engineering and Applied Science

Associate Architect

Guggenheimer Architects


Axis Group Limited

Structural Engineer

Severud Associates

MEP Engineer

Ambrosino, Depinto & Schmeider

Completion Date

2006


The work of Tod Williams and Billie Tsien

is generally remarkable for its intense

focus on material expression and attention

to architectural detailing. This is particularly

evident in their design for Skirkanich Hall,

a 58,000-square-foot (5,388-square-

meter) laboratory facility at the University

of Pennsylvania. The building envelope

consists mostly of standard campus archi-

tecture materials, brick and glass, but

here the materials have been customized

and altered from their traditional incarna-

tions. The opaque walls are clad in cus-

tom- glazed, textured, moss-green brick

that creates a sense of mass and weight.

Within these solid masses, intermittent

vertical openings are marked by curtain

walls with angled, shinglelike glass panels

that incorporate alternating bands of

transparency and translucency.

Designed primarily to bring natural light

into the corners of each floor, the curtain

wall employs stick-built framing of painted,

thermally broken extruded-aluminum

mullions suspended from the face of each

cast-in-place concrete floor slab. Each story-

high mullion angles out at its base, with

the bottom row of glass overlapping the

top row of the level below. Through vari-

ous fabrication techniques, the glass is

rendered either transparent or translucent,

depending on its location in section. At

vision areas, from sill to ceiling, the glass

is clear, low-E coated insulating glass;

spandrels are insulating glass with translu-

cent acid-etching on the second surface

and ceramic frit on the fourth surface; and

the bottom free-floating panel at each

level is tempered monolithic glass with

translucent acid-etching on the second

surface. The lower glass panels cantilever

beyond the edges of the curtain wall

frame and are each supported with two

countersunk stainless-steel bolts anchor-

ing them to the vertical mullion.

1

Typical floor plan

2

East elevation

1 2

165Skirkanich Hall

3

Installation of

glass in stick

curtain wall system

4

Curtain wall detail

5

Interior of

laboratory

3

4

5


6

Partial elevation

7

Plan

3' 9" (1.14 m)

167Skirkanich Hall

8

Section Clear insulating glass

with low-E coating


acid etch on #2 surface

and ceramic frit on #4

Tempered monolithic

glass with acid etch

on second surface

Thermally broken

extruded-aluminum

mullion

Steel bracket

Adjustable blind

Cantilevered

reinforced-concrete

floor slab

Suspended

ceiling

F

G

H

A

B

C

D

E

A

B

C

D

E

F

G

H15

' 6"

(4.7

2 m

)

Case Study 168

Case Study 169

Trutec BuildingSeoul, Korea

Curtain Wall

Custom unit system with insulating glass

structurally glazed to flat and projecting

unit frames of extruded aluminum

Program

Office and showroom spaces with

underground parking

Architect

Barkow Leibinger Architekten

Client

TKR Sang-Am

Contact Architect

Chang-Jo Architects

Facade Consultants

Arup Facade Engineering; Alutek


Schlaich Bergermann and Partner;

Jeon and Lee Partners

Completion Date

2006


The Trutec Building, containing eleven

floors of offices and showrooms, was one

of the first buildings constructed in a new

commercial development in Seoul, Korea,

known as Digital Media City, intended to

be a center of international business and

information technology. With a limited

budget and little preexisting context, the

architects developed a building envelope

that utilizes innovative digital fabrication

techniques and is characterized by unique

abstract visual effects. The curtain wall

visually captures the surrounding con-

text—whether it be the sky, cars, or other

buildings—within its fragmented glass

surfaces, reflecting it back in a kaleido-

scope of light and color.

The curtain wall is composed of a cus-

tom prefabricated unit system framed with

extruded-aluminum mullions. In order to

control solar heat gain while providing a

predominantly glass facade, a reflective

low-E coated insulating glass is used. Within

each curtain wall unit, the glass panels

are divided into nonorthogonal fragments,

some of which are angled slightly out of

the plane of the wall. The complex facade

is actually composed of just two basic

unit types: one flat, two-dimensional unit;

and one projecting, three-dimensional

unit, which can be rotated 180 degrees to

produce a third type. In order to make

such variation economically feasible, the

curtain wall fabricator used CNC digital

technology to precisely cut and assemble

the complex three-dimensional unit frames.

Barkow Leibinger Architekten success-

fully pairs a sculptural approach—a play

with light, reflections, and perception—

with technical rigor. It is this combination

of aesthetic and technical exploration that

results in the most innovative examples

of curtain wall construction.

1

Elevations

171Trutec Building

2

Curtain wall unit

configuration

diagram

3

Northwest

elevation

3-way joint

4-way joint

Plan detail

Plan detail

3

2


4

Partial elevation

5

Plan

8' 10" (2.7 m)

173Trutec Building

6

Section Adjustable

antiglare blind

Steel beam with

fireproofing

Steel column,

galvanized-metal

cladding

Suspended ceiling,

galvanized perforated-

metal panel

CNC-cut, extruded-

aluminum mullion

Insulating glass

with low-E coating

Extruded-aluminum

stack joint

Floor register with

convector and uplight

Raised floor

Steel and concrete

composite floor

F

G

H

I

J

A

B

C

D

E

A

B

CD

E

F

G H I

13'

9"

(4.2

m)

J


7

175Trutec Building

7

Night view

8

Northeast

elevation

9

Main entry

10

Interior view

11

Interior

view with

translucent

shades

8 9

10

11

Case Study 176

Case Study 177

Biomedical Science Research Building Ann Arbor, MI United States

Curtain Wall

A curvilinear double-skin curtain wall

consisting of an outer wall of monolithic

glass in a prefabricated unit system and

an inner wall of insulating glass in a stick

system, separated by an air space

Program


meter) building, with research laboratories,

offices, conference rooms, seminar

rooms, an auditorium, and a cafe

Architect


Client

University of Michigan



Structural Engineer

Severud Associates

MEP Engineer

Bard, Rao and Athanas Consulting

Engineers

Sustainability Consultant

Buro Happold

Completion Date

2006


This research facility is sited between

the University of Michigan’s main campus

and its medical school, creating a new link

between the two. Its primary programmatic

elements are discernable in the building’s

overall form. To the north, a rectilinear

L-shaped block contains laboratories and

support spaces, separated from the offices

by a skylit atrium. The offices are arranged

in an organically shaped, curvilinear band

facing south, toward the street and the

main campus. The laboratory block is

enclosed predominantly in insulating glass

and rainscreen panels of terra-cotta and

stainless steel. The most innovative enclo-

sure system is the double-skin curtain

wall of the south-facing offices.

The inner curtain wall consists of a stan-

dard stick system with extruded-aluminum

mullions, insulating glass, and insulated

spandrel panels. The outer wall is a prefab-

ricated unit system with frames of extruded

aluminum, structurally glazed single-pane

glass, and no spandrels. At curved portions,

the inner wall is faceted, while the outer

wall employs bent glass and curved mul-

lions. The two walls are separated by an

air space of about four feet, with the outer

wall supported on steel outriggers at each

mullion. The air space contains adjustable

blinds, maintenance catwalks, and track-

mounted movable platforms for glass

cleaning. In summer, the stack effect is

used to ventilate the air space; as heated

air escapes at the top of the wall, fresh air

is drawn in at the bottom. In winter, the air

space remains sealed and is heated by

the sun, creating a buffer between dispa-

rate exterior and interior air temperatures.

Compared to a conventional single-layer

glass curtain wall, the double wall provides

expansive views and a higher level of ther-

mal comfort for office occupants, improved

acoustical separation from the street, and

lower energy use.

1

Typical floor plan

1

179Biomedical Science Research Building

2

Installation of

curtain wall

3

View west from plaza

4

Double-skin glass

curtain wall at south-

facing offices

2 3

4


5

Partial elevation

6

Plan

9' (2.75 m)


7


monolithic glass

Extruded-aluminum

unit frame

Retractable blinds

Stainless-steel

spandrel panel with

insulation

Insulating glass

with low-E coating

Extruded-aluminum

stick-system mullion

Galvanized-steel

maintenance catwalk

Steel outrigger

Concrete floor on

metal deck

Adjustable blind

Suspended ceiling

F

G

H

I

J

K

A

B

C

D

E

AB C

D

E

F

G

H

I

J

K

15'

6"

(4.7

2 m

)


8

Double-skin curtain

wall in winter (left)

and summer (right)

9

Double-skin

glass curtain

wall from below

Winter Summer8


9

Case Study 184

Case Study 185

ATLAS Building Wageningen, the Netherlands

Curtain Wall

Stick system of extruded-aluminum

mullions with low-E coated insulating

vision glass and aluminum spandrel

panels, installed inboard of a precast-

concrete-diagrid structural frame

Program

Research laboratories and offices for

the Environmental Sciences Group

at Wageningen University

Architect

Rafael Vi ñoly Architects

Associate Architect

Van den Oever, Zaaijer and Partners

Client

Wageningen University

Structural/Civil Engineer

Pieters Bouwtechniek

MEP Engineer

Schreuder Groep

Building Physics

DGMR

Completion Date

2006


Located in a newly developed research

district on the somewhat rural campus

of Wageningen University, the seven-story

ATLAS Building houses 105,000 square

feet (9,755 square meters) of laboratories

and office space organized around a central

skylit atrium. The building presents a sculp-

tural yet strikingly simple facade dominated

by an external precast-concrete diagrid

that wraps around all four sides. The exo-

skeleton configuration was designed by

Rafael Vi ñoly Architects to provide flexi-

ble, column-free interior spaces that could

be easily transformed and repartitioned

according to future needs.

Here, the relationship of structure to skin

is an intriguing inversion of the typical cur-

tain wall configuration—rather than a glass

skin enclosing the building structure, the

building appears as a glass box set within

a protective latticework of concrete. The

diagrid structure also acts as an external shad-

ing device for the floor-to-ceiling glass wall

installed approximately two and a half feet

behind it. At each level, the wall is divided

into three horizontal bands of glass, with the

middle strip incorporating operable hopper

windows. The curtain wall provides the inte-

rior spaces with ample daylighting, natural

ventilation, and a strong visual connection

to the surrounding landscape. The external

space between the wall and structure con-

tains retractable blinds for solar control and

maintenance catwalks on each level.

1

West elevation

2

Interior view

3

Diagrid structure

at corner

4

Maintenance

catwalk between

external diagrid

structure and

curtain wall

1

187ATLAS Building

2

3

4


5

Partial elevation

6

Plan

5' 11" (1.80 m)

189ATLAS Building

7

Section Precast-concrete

diagrid structure

Steel grate mainte-

nance catwalk

Exterior adjustable

blinds

Painted aluminum

spandrel panel

with insulation


low-E coating

Painted extruded-

aluminum mullion

In-swinging oper-

able window

Finished floor on

reinforced-concrete

slab

Suspended ceiling

F

G

H

I

A

B

C

D

E

A

B

C

D

E

F

G

H

I

11'

10"

(3.6

m)

Case Study 190

Case Study 191

Blue Tower New York, NY United States

Curtain Wall

A semicustom unit system with

tinted insulating glass and operable

windows set within frames of

extruded-aluminum mullions

Program

Residential tower with thirty-two

apartments

Design Architect

Bernard Tschumi Architects

Executive Architect

SLCE Architects

Client

Angelo Cosentini and John Carson


Israel Berger and Associates

Structural Engineer

Thornton Tomasetti

MEP Engineers

Ettinger Engineers

Completion Date

2007


Blue Tower is one of a handful of recently

constructed mid-rise residential buildings

now transforming the skyline of New York

City’s Lower East Side. The sixteen-story,

cast-in-place concrete structure contains

thirty-two apartments with a total floor area

of 55,000 square feet (5,110 square meters).

Two aspects of the design give Blue Tower

its distinctive appearance: the geometry

of the building form and the expression

of the curtain wall.

Utilizing air rights to the adjacent site,

the tower cantilevers over an existing two-

story commercial building; the massing

of the tower also responds creatively to

zoning setback requirements, with angled

walls that slope in and out. The building is

covered with approximately 4,000 pieces of

glass in a prefabricated-unit-system curtain

wall. The pixelated effect of the facade is

achieved through the use of six different

types of glass: blue- and gray-tinted insu-

lating vision glass and four shades of blue

spandrel glass. The curtain wall incorpo-

rates operable windows for natural ventila-

tion as well as louvered vents that supply

fresh air to air-conditioning units.

Although based on a standard prefabri-

cated unit system, the curtain wall has been

somewhat customized through novel glass

selection and unique mullion extrusions,

necessary to accommodate the unusual

corner geometries where sloped and

vertical walls meet. The curtain wall fabrica-

tor, AGT, utilized extensive digital three-

dimensional modeling, CNC fabrication,

and GPS site survey techniques to ensure

proper detailing and installation of the

geometrically complex curtain wall.

1

North-south sectionRF

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

193Blue Tower

2

Curtain wall unit

installation

3

Detail at west

elevation

4

Levels thirteen

to sixteen

2 3

4


5

Partial elevation

6

Plan

3' 4" (1.02 m)

195Blue Tower

7

Section Tinted insulating glass

with low-E coating

Extruded-aluminum

stack joint

Extruded-aluminum

mullion

Operable window

Reinforced-concrete

flat slab

Curtain wall anchor

Continuous fire-safe

insulation at slab

edge

Concrete column,

gypsum-board

cladding

F

G

H

A

B

C

D

E

A

B

D

E

F

G

H

C

10' 4

" (3

.15 m

)


8

Unfolded elevation

9

View from south

8

197Blue Tower

9

Case Study 198

Case Study 199

The Nelson-Atkins Museum of Art Kansas City, MO United States

Curtain Wall

A custom double-skin system incorporating

an outer wall of translucent, sandblasted

channel-glass planks separated by a 3-foot

(0.9-meter) space from an inner wall of

translucent laminated glass

Program


meter) addition to the original 1933

building of the Nelson-Atkins Museum

that includes new permanent and special

exhibition galleries, education areas,

conservation facilities, meeting spaces,

shops, administrative offices, and

underground parking

Architect

Steven Holl Architects

Local Architect

Berkebile Nelson Immenschuh McDowell

Architects

Client

Nelson-Atkins Museum of Art


R. A. Heintges and Associates

Structural Engineer

Guy Nordenson and Associates

Associate Structural Engineer

Structural Engineering Associates

Mechanical Engineers

Ove Arup and Partners; W. L. Cassell

and Associates

Lighting Consultant

Renfro Design Group

Completion Date

2007


Steven Holl Architects’ expansion of the

Nelson-Atkins Museum of Art, known as

the Bloch Building, fuses the new architec-

ture with the museum’s sprawling sculpture

garden. New gallery spaces are arranged

in a linear fashion along the garden,

marked by five glass-clad volumes, which

the architect refers to as “light-gathering

lenses” that emerge from the garden

landscape. The lenses incorporate a com-

plex double-skinned glass-wall system,

which provides the galleries with diffused

natural light by day (modulated by com-

puter-controlled screens within the wall

cavity). The building glows from within

at night, turning the lenses into large-

scale sculptures in their own right.

Though interrupted in some areas by

bands of clear insulating glass that provide

direct views inside and out, the primary

curtain wall features various forms of con-

tinuous translucent glass, which react

dynamically to changing light conditions

throughout the day. The typical double-

layer curtain wall incorporates an outer

skin of interlocking, translucent, U-shaped

channel-glass planks with a sandblasted

finish and translucent Okalux insulation

between the planks. Because of its structural

shape, channel glass is self-supporting and

does not rely on mullions or any other form

of vertical support, even when used in

heights up to 20 feet (6.1 meters). The only

metal element in such a system is the

horizontal aluminum channel that supports

the plank at its top and bottom edges.

The inner wall, separated by a three-foot

(0.9-meter) air cavity housing blinds and

light fixtures, consists of floor-to-ceiling

translucent, acid-etched, UV-blocking

laminated glass. Low-iron glass was used

throughout to avoid the natural greenish

tint of regular clear glass.

1

201The Nelson-Atkins Museum of Art

1

Translucent channel

glass curtain wall

2

View of inner wall

with clear and acid-

etched glass

3

Exterior view of

channel glass wall

at night

3

2


4

Partial elevation

5

Plan


6

Section Sandblasted low-iron

channel glass with

translucent insulation

Extruded-aluminum

stack joint anchored

to steel tube

Laminated acid-etched

safety glass


Galvanized-steel-

grate catwalk

Light fixture

Fireproofed

steel beam

Automated blinds

Concrete floor slab

on metal deck

Suspended ceiling

F

G

H

I

J

A

B

C

D

E

A

B

CD

E

F

G

H

I

J

12' (

3.6

6 m

)


7

Longitudinal

section

8

Translucent glass

lenses emerging

from sculpture

garden

7

8


9

Exterior of glass

lense

10

Daylit entrance

lobby

9

10

Case Study 206

Case Study 207

The New York Times Building New York, NY United States

Curtain Wall

Custom unit system with a frame of

extruded-aluminum mullions supporting

insulating glass and an external brise-

soleil of horizontal ceramic rods

Program

Office space, ground-floor retail space,

an open-air garden, and an auditorium

Architects

Renzo Piano Building Workshop;

FXFOWLE Architects

Client

The New York Times Company

Developer

Forest City Ratner Companies

Interior Architect

Gensler

Exterior Wall Consultant

Heitman and Associates; Forst Consulting

Company


Thornton Tomasetti

MEP Engineer

Flack and Kurtz

Completion Date

2007


In 2000, Renzo Piano won the competition

to build the new headquarters of The New

York Times Company. His design for the

1.5-million-square-foot (139,354-square-

meter), fifty-two-story tower features a

custom-unit curtain wall system with floor-

to-ceiling insulating glass and a second

layer of external sunshading ceramic rods.

The building represents an application

of the brise-soleil concept on an immense

scale, unprecedented in New York City.

The curtain wall incorporates ultraclear

insulating glass in prefabricated units,

framed by extruded-aluminum mullions

that are anchored to the edge of each

floor slab. The vertical mullions, spaced

on 5-foot (1.5-meter) centers, also support

the external sun-shading veil of ceramic

tubes—positioned about eighteen inches

in front of the glass—which reduce solar

heat gain by up to 50 percent. An innova-

tive lighting system, developed in associa-

tion with Lawrence Berkeley National

Laboratory, takes advantage of the natural

light coming through the curtain wall and

uses automated dimming and shade sys-

tems to minimize the need for electric

power, reducing energy consumption by

30 percent. In addition to providing critical

sun-shading, the ceramic rods (186,000

in all) create a unique diaphanous skin

that defines the character of the building.

The white rods reflect external environ-

mental conditions, altering color with the

changing sky—gray in overcast weather,

bright white in midday sun, orange and

pink as the sun rises and sets. During the

building’s first year of use, the horizontal

rods proved an irresistible invitation to

three attention-seekers who scaled the

curtain wall (two reached the top of the

building using the ceramic rods like rungs

in a ladder), prompting the owner to

remove those closest to the base of the

building in the summer of 2008.

1

Typical tower floor

plan

2

West elevation at

sunset

21

209The New York Times Building

3

Aluminum-framed

glass curtain wall with

external brise-soleil

of ceramic rods

4

Interior view

3

4


5

Partial elevation

6

Plan

5' (1.52 m)


7

Section Glazed ceramic tubes

with internal aluminum

connection

Painted aluminum

vertical strut

Painted aluminum

horizontal strut


Low-iron insulating

glass with low-E

coating

Painted extruded-

aluminum unit frame

Painted aluminum

spandrel panel

Automated internal

shade

Raised floor over

concrete slab on deck

Suspended ceiling

F

G

H

I

J

A

B

C

D

E

A B

C

D

E

F

G

H

I

J

13' 9

" (4

.19 m

)

3' 4

" (1

.02 m

)


8


8

Night view of tower

9

Ceramic-rod brise-soleil

at main entrance

9

Case Study 214

Case Study 215

Spertus Institute of Jewish Studies Chicago, IL United States

Curtain Wall

Custom hybrid system of structural,

preglazed, silkscreened insulating glass

units in multiple shapes mounted onto

stick-built mullions of extruded aluminum

Program

Permanent and temporary exhibition

galleries, classrooms, a library, an

auditorium, conference rooms, a cafe,

and a gift shop

Architect

Krueck + Sexton Architects

Associate Architect

VOA Associates

Client



Shepphird Associates

Structural Engineer

Tylk Gustafson Reckers Wilson Andrews

MEP Engineer

Environmental Systems Design

Completion Date

2007


The new Spertus Institute of Jewish Studies

both contrasts with and complements the

line of traditional masonry buildings it

joins along Chicago’s famous Michigan

Avenue, facing eastward toward Grant Park.

Unapologetically contemporary, though

respectful of contextual cues such as

height and massing, the building’s main

facade measures 80 by 181 feet (24.4 by

55.2 meters) and is clad entirely in a folded,

faceted custom glass curtain wall. The

effect of this crystalline structure is a com-

bination of transparency and reflectivity,

suggesting a sense of openness and con-

nectivity that suits the institute’s mission.

The curtain wall incorporates 726 indi-

vidual pieces of glass in 556 different

shapes. Portions of the undulating wall

project outward by as much as 5 feet (1.5

meters) and inward by 2 feet (0.6 meters).

With such variation in orientation, the glass

surfaces simultaneously transmit and reflect

sunlight through and across the facade.

The double-pane insulating glass includes

a high-performance low-E coating on the

second surface for improved thermal per-

formance as well as a silkscreened pattern

of white ceramic frit dots for solar shading

covering 40 percent of the surface. Visible

from within a few feet, the dot pattern

disappears when viewed from greater dis-

tances and lends the glass a softness and

material presence. The inner pane of the

insulating-glass unit is laminated with a

PVB interlayer, providing several benefits:

improved safety, better acoustical insula-

tion, and protection from potentially

damaging UV light.

The glass is factory-glazed along each

edge with a structural silicone sealant that

adheres it to a minimal frame of extruded

aluminum. These units are then mounted

onto Y-shaped aluminum mullions, span-

ning vertically from floor to floor, that bend

and twist as the shape of the wall dictates.

Near the center of the facade, a portion of

the wall peels away from the building mass

to form a kind of canopy, sheltering the

street-level entryway and revealing the

construction method of the curtain wall.

1

Longitudinal section

2

View from Michigan

Avenue

1

2

217Spertus Institute of Jewish Studies

3

Curtain wall extension

forms canopy at entrance

4

Interior view of pre-

glazed unit frame and

Y-mullions

5

View toward Lake

Michigan

3

4

5


6

Partial elevation

7

Plan

4' 4" (1.32 m)

219Spertus Institute of Jewish Studies

8


laminated insulating

glass with low-E

coating and ceramic

frit silkscreen

Extruded-aluminum

unit frame

Bent extruded-

aluminum mullion

Adjustable translucent

blind

Radiator

Concrete slab on

metal deck

Fireproofed steel

beam

Suspended ceiling

F

G

H

A

B

C

D

E

A

B C

D

E

F

G

H

14'

(4.2

7 m

)

7' (

2.1

3 m

)


9

Interior view

9

221

Rotating knifeplate extrusion

Anchor plateY-mullion

Alum. framingextrusion

S.S. hook plate

Alum. saddle extrusion

Work point

1-7/16” laminated frittedlow-iron glazing unit


10

Diagram of curtain

wall facets

11

Curtain wall

axonometric

12

Plan detail at

typical Y-mullion

10

11

12

01

02

03

0405

06

07

08

09 10 11

12 13

14 15

16 17

18 1920

26

32

27 30 3128 29

33

37

38

3934 35 36

23

25

24

21

22

252222555

21

22

4424422224422444

2

2

Case Study 222

Case Study 223

United States Federal Building San Francisco, CA United States

Curtain Wall

High-performance window wall with floor-

to-ceiling insulating glass, operable vents,

and external sun-shading provided by a

second skin of perforated stainless-steel

panels at the southeast elevation and

translucent glass fins at the northwest

Program

Office space for U.S. federal departments,

including Labor, Defense, Health and

Human Services, and Agriculture; health

and fitness center; conference facilities;

child care center; and a cafe

Architect

Morphosis

Executive Architect

Smith Group

Client

U.S. General Services Administration


Curtain Wall Design and Consulting

Structural and MEP Engineer

Ove Arup and Partners

Civil Engineer

Brian Kangas Foulk

Natural Ventilation Modeling

Lawrence Berkeley National Laboratory

Artist Collaborators

James Turrell, Ed Ruscha, Rupert Garcia,

Hung Liu, Raymond Saunders,

William Wiley

Completion Date

2007


The U.S. General Services Administration,

acting as client for the new 600,000-square-

foot (55,741-square-meter) United States

Federal Building in San Francisco, sought

an exemplary building that would reduce

consumption of natural resources, minimize

waste, and create a healthy, productive

workplace for the building’s daily users.

The project team, headed by the architects

of Morphosis, responded with a design

featuring advanced sustainable technolo-

gies in an emphatically nontraditional wrap-

per. The building envelope is a machine

that not only provides light, views, and

protection from the elements, but also cir-

culates air and reduces energy use.

The main component of the complex

is an eighteen-story tower conceived with

a slender floor plate measuring 65 feet

(19.8 meters) wide, to maximize views and

incoming light and to enable natural cross-

ventilation of the offices, taking advantage

of San Francisco’s temperate climate. The

two broad faces of the tower are enclosed

by walls of clear floor-to-ceiling insulating

glass with operable windows. To protect

these walls from excessive solar heat gain,

sun-shading is provided at the southeast

elevation by an external armature of per-

forated stainless-steel panels and, at the

northwest elevation, by light-diffusing

translucent glass fins. The articulation of

these two shading systems, with the details

of their fabrication and assembly clearly

on display, defines the building’s charac-

ter: a machine aesthetic that celebrates

the importance of orientation and

responsiveness to climate.

The building skin is not static. A central-

ized computer system automatically opens

and closes windows and sunshade panels

in response to interior air temperature and

external environmental conditions, such as

temperature, wind speed, and wind direc-

tion. (Manual override controls are also

provided for use by individuals.) At night,

the windows open to flush out heat that

has built up during the day, allowing night-

time air to cool the building’s concrete

interior. The thermal mass of the exposed

concrete walls, columns, and ceilings keeps

the interior cool throughout the day.

1

Interior view at office:

aluminum-framed

window wall with insu-

lating glass, operable

windows, and external

sun-shading panels

2

Northwest elevation

3

Translucent glass fins at

northwest elevation

1

225United States Federal Building

2

3


4

Partial elevation

5

Plan

7' 4" (2.24 m)


6

Section Perforated stainless-

steel sunshade panels

Galvanized-steel

tube frame


Galvanized-steel-

grate catwalk

Insulating glass

Operable out-

swinging windows

Extruded-aluminum

unit frame

Radiator

Reinforced-

concrete slab

Raised floor

F

G

H

I

J

A

B

C

D

E

A

B

C

D

E

F

G

H

I J

13'

(3.9

6 m

)


7


7

Perforated stainless-

steel skin at east corner

8

East corner

9

Oblique view from plaza

10

Perforated stainless-

steel sunshade in front

of glass and aluminum

window wall

10

98

Case Study 230

Case Study 231

Yale Sculpture Building New Haven, CT United States

Curtain Wall

Standard stick system customized with

an external brise-soleil, triple-pane

insulating glass, and high-performance

spandrel insulation

Program

Art studios, a gallery, machine shops,

classrooms, and offices

Architect


Client

Yale University

Structural Engineer

CVM Engineers

MEP and Civil Engineer

BVH Integrated Services

Environmental Consultant

Atelier Ten

Completion Date

2007


In designing the new 51,000-square-

foot (4,738-square-meter) home for Yale

University’s sculpture department, Kieran-

Timberlake Associates was challenged to

provide a high degree of transparency and

natural light for the art studios while achiev-

ing ambitious overall energy-efficiency

objectives, all within the context of New

England’s harsh seasonal weather extremes.

The building envelope plays a major role in

the attainment of these goals, through the

use of a high-performance curtain wall with

innovative glass specification and solar

design strategies. The Sculpture Building

earned a LEED Platinum rating and was

named one of 2008’s “Top Ten Green Projects”

by the American Institute of Architects

Committee on the Environment.

The curtain wall framing consists of

standard stick-built mullions of thermally

broken, extruded aluminum with external

glazing caps. This system was customized

through the use of high-performance

glazing, including triple-pane, argon-filled,

low-E coated insulating glass at vision

areas; and on the exterior, superinsulated

spandrel panels incorporating double-pane,

low-E insulating glass, a 3-inch (7.6-centi-

meter) air space, and a translucent Kalwall

fiberglass panel with aerogel insulation.

The spandrel panels achieve an insulation

value of R-20, while the average value of

the curtain wall system overall is R-8—

more than four times better than a con-

ventional curtain wall. Due to the use of

translucent spandrels, the entire curtain

wall transmits natural light, even though

transparent glass is limited to vision areas

(approximately 60 percent of the surface),

and therefore, the need for artificial light-

ing is greatly reduced. The curtain wall

also contains numerous operable windows

for natural ventilation.

The other important custom feature

of the curtain wall is the array of horizontal

aluminum sunshade louvers supported

on vertical aluminum channels located

approximately 2 feet (0.6 meters) outside

of the curtain wall, on the south and east

elevations. The angle of the louvers is

calibrated to allow low-angle winter sun

to reach the glass while blocking direct

summer sun and guarding against exces-

sive solar heat gain and glare.

1

East elevation at night

1

233Yale Sculpture Building

2

Aluminum brise-soleil

at southeast corner

3

Glass and aluminum

curtain wall (left)

and aluminum

brise-soleil (right)

4

Interior view at

sculpture studio

4 3

2


5

Partial elevation

6

Plan

5' (1.52 m)

235Yale Sculpture Building

7

Section Aluminum sunshade

louvers

Vertical aluminum

channels

Triple-pane insulating

glass with low-E

coating and argon fill

Double-pane

insulating glass with

low-E coating

Translucent fiberglass

panel with aerogel

insulation

Thermally broken

extruded-aluminum

mullion

Adjustable

translucent blind

HVAC console

Aluminum bracket

Concrete slab on

deck over structural

steel framing

F

G

H

I

J

A

B

C

D

E

A

B

C

DE

F

G

HJI

14' (

4.2

7 m

)

3' 1

1"

(1.2

0 m

)8

' 4"

(2.5

4 m

)

Case Study 236

Case Study 237

The Cathedral of Christ the Light Oakland, CA United States

Curtain Wall

Custom prefabricated unit system with

laminated glass in extruded-aluminum

framing mounted to a laminated-wood

structural system.

Program

A cathedral, mausoleum, offices, library,

conference center, cafe and bookstore,

and underground parking

Architect


Architect of Record

Kendall/Heaton Associates

Client

Diocese of Oakland

Structural Engineer


Mechanical Engineer

Taylor Engineering

Electrical Engineer

Engineering Enterprise

Completion Date

2008


The Diocese of Oakland wanted its new

cathedral to embody light, drawing on

deep metaphoric associations in religious

traditions. The cathedral complex, built

to replace an older one that was damaged

during the 1989 San Francisco Bay earth-

quake, includes a concrete base, housing

offices, meeting spaces, residences for

clergy, and a bookstore and cafe. Rising

from the rooftop plaza of the base is the

luminous main sanctuary, a tapered space

measuring 100 feet (30.5 meters) in height,

forming two interlocking spherical grids

that are draped in glass and topped by

a central glass oculus.

Within the sanctuary, which seats 1,350

people, the main building structure is com-

posed of a series of curved and straight

laminated Douglas fir columns that extend

the full height of the building. The skin is

formed by a custom curtain wall system,

with unit frames of extruded aluminum

holding 1,028 panes of laminated, low-E

coated glass that are silkscreened with a

custom-patterned ceramic frit. This effect

renders the glass translucent, serving to

diffuse the light passing through the curtain

wall, and the glass walls glow at night when

lit from within. Each glass unit measures

4.5 by 10 feet (1.4 by 3 meters). The curtain

wall is anchored to horizontal steel tubes

that span between the massive upright

wooden columns. At the top of the wall,

vertical stainless-steel mullion extensions

point toward the sky. The interior face of

the enclosure is formed by wooden louvers

that simultaneously diffuse and redirect

sunlight to the interior, partially screen the

curtain wall, and provide brief glimpses

between louvers to create a sense of

mystery as to the source of the light.

1

West elevation

1

239The Cathedral of Christ the Light

2

Internal structure

revealed by sunlight

3

Laminated glass with

custom ceramic-frit

pattern in unit frames

of extruded aluminum

4

South elevation

2

3

4


5

Partial elevation

6

Plan

4' 6" (1.37 m)


7

Section Laminated glass with

low-E coating and

custom-patterned

ceramic frit

Extruded-aluminum

unit frame

Horizontal steel tube

Laminated Douglas

fir column

Laminated Douglas

fir sunshade louver

Steel rod

cross-bracing

Reinforced-

concrete base

Light fixture

Maintenance

walkway

F

G

H

I

A

B

C

D

E

A

B

C

D

D

E

F

G

I

H

10' 2

" (3

.1 m

)


8

Ground-floor plan

9

Oculus at center of

sanctuary ceiling

with suspended

aluminum panels to

diffuse light

9

8


10

Detail of curtain wall

connections at south

elevation

11

Laminated wood

structure and louvers

at interior

12

Longitudinal section

12

1110

Case Study 244

Case Study 245

100 Eleventh Avenue New York, NY United States

Curtain Wall

Custom unit system with semireflective,

low-E coated insulating glass set at

various angles within aluminum and

steel frames

Program

Residential condominiums

Design Architect


Executive Architect

Beyer Blinder Belle Architects

and Planners

Client

West Chelsea Development Partners

Curtain Wall Consultants

CCA Facade Technology; UAD Group;

Front

Structural Engineer

DeSimone Consulting Engineers

MEP Engineer

Atkinson Koven Feinberg Engineers

Environmental Consultant

Roux Associates

LEED Consultant

YRG Sustainability Consultants

Completion Date

2009


This twenty-three-story residential tower

in Manhattan’s Chelsea neighborhood

displays a dichotomy between front and

back, solidity and lightness. The front of

the building, facing west and south toward

the nearby Hudson River, presents a patch-

work of semireflective glass in curtain wall

units of various shapes and sizes wrapping

around a curved corner. What may be

considered the back of the building, facing

north and east, is outfitted in precast-

concrete panels faced in black brick with

smaller punched-window openings.

From a distance, the glass curtain wall

looks like a thin reflective membrane,

applied to the building in the direction of

the major views; from a closer vantage

point, it reveals itself as an intricate collage

of angled glass panels set within an irregular

network of narrow mullions. Insulating glass

with a low-E coating and laminated inner

pane (for safety and UV protection) is sup-

ported by extruded-aluminum frames,

which are contained within larger prefabri-

cated unit frames of powder-coated steel

tubes. These steel frames, bolted to the

edge of each floor slab, form megaunits,

ranging from 11 to 16 feet (3.4 to 4.9 meters)

tall and up to 37 feet (11.3 meters) wide,

each holding numerous glass panels

tilted in different directions—left, right,

up, and down. In all, there are more than

1,600 individually sized glass panels.

This diversity of orientation results in

striking optical effects. The glass wall oscil-

lates between transparency and reflectivity,

with no two adjacent glass panels the

same. The irregular mullion spacing also

serves to frame very specific views from

within. Because of the curtain wall’s frac-

tured imagery, the facade conveys a notion

of individuality and specificity, resisting

the tendency toward uniformity.

1

Rendering of west

elevation

2

Reinforced-concrete

structure under

construction

1

2

247100 Eleventh Avenue

3

Shifting reflections

over the course of

one day

4

Interior rendering of

steel and aluminum

curtain wall framing

with angled

insulating glass

3

4


5

Partial elevation

6

Plan

17' (5.18 m)

249100 Eleventh Avenue

7

Section Laminated insulating

glass with low-E

coating

Extruded-aluminum

glazing adapter on

steel tube unit frame

Steel curtain wall

anchor and fire-safe

insulation at slab edge

Extruded-aluminum

horizontal mullion

Adjustable shades

Finished floor

on reinforced-

concrete slab

F

A

B

C

D

E

A

B

C

D

E

F

12'

(3.6

6 m

)

Case Study 250

Case Study 251

166 Perry Street New York, NY United States

Curtain Wall

Custom unit system featuring vertical

and sloped low-E coated insulating

glass supported in unit frames of

extruded aluminum

Program

Residential condominiums

Architect

Asymptote

Client

Perry Street Development Corporation

Facade Consultants

Design phase: Front; Construction phase:


Structural Engineer

Robert Silman Associates

MEP Engineer

Forum Engineering

Energy Model Consultant

Kinetix

Completion Date

2009


Sited next to Richard Meier’s iconic 173

and 176 Perry Street towers located near

the Hudson River waterfront in Manhattan’s

West Village, 166 Perry Street provides an

alternate take on the glass-clad residential

building. Here, the glass wall is not a con-

tinuously flat, vertical surface; the curtain

wall angles variably inward and outward

in vertically articulated bands. Due to the

specification of a slightly reflective low-E

coating on the glass and the angled posi-

tioning of the units, the curtain wall reflects

both sky and ground conditions, changing

color throughout the day and presenting

a collagelike assemblage of contextual

imagery. The primary focus of the building

envelope design is thus a celebration of

access to light, air, and views—precious

commodities in any Manhattan residence.

Illustrative of the ongoing globalization

of the facade industry, 166 Perry Street’s

curtain wall units were assembled and

tested in Shanghai, China, with finished

prefabricated units then shipped to the

construction site, where they were installed

on premounted anchors at the edge of

each floor slab. The slabs cantilever

beyond the structural frame, allowing for

uninterrupted vision glass from floor to

floor, without spandrel panels. The custom-

designed unit frames consist of extruded-

aluminum mullions, to which insulating

glass is structurally glazed with silicone

sealant. Out-swinging operable windows

are provided within most of the curtain

wall units for natural ventilation.

1

Mock-up of cur-

tain wall units

2

Installation of

curtain wall units

1

2

253166 Perry Street

3

Rendering of faceted

curtain wall units

4

Rendered exterior

view at midday

5

Rendered exterior

view at dusk

3

4 5


6

Partial elevation

7

Plan

5' (1.52 m) 8' (2.44 m)

255166 Perry Street

8

Section Laminated insulat-

ing glass with low-E

coating

Extruded-aluminum

unit frame

Out-swinging operable

window

Fire-safe insulation

Finished floor on

concrete deck

Adjustable shadeF

A

B

C

D

E

A

B

C

E

F

13'

(3.9

6 m

)

D

Acknowledgments

The research that resulted in this book was supported by grants from the Graham

Foundation for Advanced Studies in the Fine Arts and a Creative Research Award from

the College of Fine and Applied Arts at the University of Illinois at Urbana-Champaign.

I am grateful for the encouragement of colleagues in the School of Architecture at

the University of Illinois, including Director David Chasco, Botond Bognar, and Jeff Poss.

I am also thankful for the enthusiasm and insight of the numerous graduate students

that participated in my curtain wall seminar at the University of Illinois over the past several

years. And, while I’m at it, I will take this opportunity to thank a few teachers who were

particularly important figures in my own architectural education: Sheila Kennedy, Leslie

Gill, and Alejandro Lapunzina.

Much of my knowledge of curtain walls in contemporary architecture was gained

through years of professional practice and collaborative work with fellow architects and

engineers. My time with the firm of R.A. Heintges & Associates, in New York City, was

especially enlightening in this regard, due in large part to Robert Heintges, John Pachuta,

Katherine Miller, Piergiorgio Pesarin, and Aulikki Sonntag, among many other important

mentors and friends.

This book is dedicated to Sharon and Ken Murray, with gratitude for a lifetime of

encouragement and support.

Scott Murray

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Frontmatter

p. 2: photograph © Corinne Rose

Part I

p. 9, clockwise from top left: originally

published in Architectural Record, January-

March, 1895, 305; photograph © Artists Rights

Society (ARS), New York/ADAGP, Paris/FLC;

Library of Congress, Prints & Photographs

Division, HABS NY, 31-NEYO, 151-1;

photograph © Scott Murray.

Essay 11.1, originally published in Architectural

Record, January–March, 1895, 305; 1.2, Library

of Congress, Prints & Photographs Division,

HABS ILL, 16-CHIG, 23-1; 1.3–1.4, photograph

© Scott Murray; 1.5, Library of Congress,

Prints & Photographs Division, HABS ILL,

16-CHIG, 66-1; 1.6, photograph © Chicago

Architectural Photographing Company; 1.7,

drawings by Jason Wheeler; 1.8, photograph ©

Scott Murray; 1.9, Library of Congress, Prints &

Photographs Division, HABS ILL, 16-CHIG, 30-2;

1.10–1.12, drawings by Jason Wheeler; 1.13,

photograph © Scott Murray; 1.14, drawings

by Jason Wheeler; 1.15, Historic Architecture

and Landscape Image Collection, Ryerson and

Burnham Archives, The Art Institute of Chicago,

Reproduction © The Art Institute of Chicago;

1.16, RIBA Library Photographs Collection; 1.17,

RIBA Library Photographs Collection; 1.18,

photograph © Botond Bognar; 1.19, Kansas

Collection, Spencer Research Library, University

of Kansas Libraries; 1.20, Library of Congress,

Prints & Photographs Division, HABS CAL, 38-

SANFRA, 149-1; 1.21, drawing by Scott Murray;

1.22, photograph © Botond Bognar.

Essay 22.1, © Artists Rights Society (ARS), New York/

ADAGP, Paris/FLC; 2.2–2.3, © Artists Rights

Society (ARS), New York/VG Bild-Kunst, Bonn.

Digital Image © The Museum of Modern Art/

Licensed by Scala/Art Resource, NY.

Essay 33.1, Library of Congress, Prints & Photographs

Division, HABS NY, 31-NEYO, 151-1; 3.2,

drawing by Jason Wheeler; 3.3, originally

published in Architectural Forum, November

1950, reprinted courtesy of General Bronze;

3.4–3.5, drawings by Scott Murray; 3.6–3.7,

photographs © Nelson Kon; 3.8, Library of

Congress, Gottscho-Schleisner Collection; 3.9,

drawing by Jason Wheeler; 3.10–3.11, drawings

by Scott Murray; 3.12, photograph by Ezra

Stoller © Esto; 3.13, drawing by Jason Wheeler;

3.14, Library of Congress, Gottscho-Schleisner

Collection; 3.15–3.29, all drawings by Scott

Murray, all photographs © Scott Murray; 3.30,

RIBA Library Photographs Collection; 3.31,

drawings by Jason Wheeler; 3.32, Library of

Congress, Prints & Photographs Division, HABS

MASS, 9-CAMB, 69-3; 3.33, photograph ©

Scott Murray; 3.34–3.35, photographs courtesy

Perkins+Will; 3.36–3.37, drawings by Jason

Wheeler; 3.38, photograph by Ezra Stoller ©

Esto; 3.39–3.40, photographs © Scott Murray.

Essay 44.1–4.4, photographs © Scott Murray and

drawing by Scott Murray; 4.5–4.6, photographs

© Josh Wood; 4.7, photograph © Alastair

Hunter/RIBA Library Photographs Collection;

4.8, photograph © John Donat/RIBA Library

Photographs Collection; 4.9, photograph ©

Scott Murray; 4.10, drawings by Scott Murray;

4.11–4.12, photographs © Barbara Elliott

Martin; 4.13–4.14, drawings by Jason Wheeler;

4.15–4.18, photographs © Scott Murray; 4.19,

Library of Congress, Prints & Photographs

Division, HABS WIS, 51-RACI, 5-6; 4.20–4.26,

all photographs © Scott Murray and drawings

by Scott Murray; 4.27–4.28, photographs ©

Botond Bognar.

Illustration Credits

Part II

p. 65: both photographs © Scott Murray.

Essay 55.1–5.3, photographs © Scott Murray; 5.4,

drawing by Jason Wheeler; 5.5, photograph ©

Scott Murray; 5.6, drawing by Jason Wheeler;

5.7–5.15, all photographs © Scott Murray and

all drawings by Scott Murray.

Essay 66.1, diagram adapted by Scott Murray, from

James Marston Fitch, American Building:

The Environmental Forces That Shape It;

6.2–6.3, drawing and chart by Scott Murray;

6.4, image produced using THERM software

from Lawrence Berkeley National Laboratory;

6.5, photograph © Scott Murray.

Part III

pp. 84–85: all images courtesy the architects.

The New 42nd Street Studiosp. 86, photograph © Scott Murray; p. 87,

drawing courtesy Platt Byard Dovell White;

figures 1–2, courtesy the architects; 3–4,

photographs © Scott Murray; 5–7, drawings by

Scott Murray based on information provided by

the architects; 8, courtesy the architects; 9–10,

photographs © Scott Murray; 11, photograph

© Dennis Gilbert/View/Esto.

Melvin J. and Claire Levine Hallp. 94, photograph © Scott Murray; p. 95,

drawing courtesy KieranTimberlake Associates;

figures 1–2, photographs © Scott Murray; 3,

photograph © KieranTimberlake Associates;

4, photograph © Scott Murray; 5, drawings

courtesy the architects; 6–8, drawings by Scott

Murray based on information provided by the

architects.

the architects.

Trutec Buildingp. 168, photograph © Corinne Rose; p. 169

and figures 1–2, drawings courtesy Barkow

Leibinger Architekten; 3, photograph © Amy

Barkow/Barkow Photo; 4–6, drawings by Scott

Murray based on information provided by

the architects; 7, photograph © Corinne Rose;

8, photograph © Amy Barkow/Barkow Photo;

9, photograph © Corinne Rose; 10–11,

photographs © Amy Barkow/Barkow Photo.

Biomedical Science Research Buildingp. 176, photograph © Scott Murray; p. 177 and

figure 1, drawings courtesy Polshek Partnership

Architects; 2, photograph © Aislinn Weidele/

Polshek Partnership LLP; 3–4, photographs

© Scott Murray; 5–7, drawings by Scott Murray

based on information provided by the

architects; 8, drawing courtesy the architects;

9, photograph © Scott Murray.

ATLAS Buildingp. 184, photograph © Scott Murray; p. 185,

drawing courtesy Rafael Viñoly Architects; figure

1, photograph © Scott Murray; 2, photograph

© Luuk Kramer; 3–4, photographs © Scott

Murray; 5–7, drawings by Scott Murray based

on information provided by the architects.

Blue Towerp. 190, photograph © Scott Murray; p. 191 and

figure 1, drawings courtesy Bernard Tschumi

Architects; 2, photograph © Joseph O. Holmes;

3–4, photographs © Scott Murray; 5–7, drawings

by Scott Murray based on information provided

by the architects; 8, drawing courtesy the

architects; 9, photograph © Nat Ward.

Terrence Donnelly Centre for Cellular and Biomolecular Researchp. 132, photograph by Tom Arban; p. 132 and

figure 1, drawings courtesy architectsAlliance

and Behnisch Architekten; 2–5, photographs

by Tom Arban; 6–8, drawings by Scott Murray


architects; 9, photograph by Tom Arban.

Torre Agbarp. 140, photograph © Dennis Gilbert/View/

Esto; p. 141 and figure 1, drawings courtesy

Ateliers Jean Nouvel; 2, photograph © Scott

Murray; 3, diagram courtesy the architect; 4,

photograph © Philippe Ruault; 5, photograph

© Scott Murray; 6–8, drawings by Scott Murray


architects; 9, photograph © Philippe Ruault; 10,

photograph © Scott Murray; 11, photograph ©

Hector Milla; 12, photograph © Scott Murray.

Torre Cubep. 148, photograph © Scott Murray; p. 149 and

figures 1–2, drawings courtesy Estudio Carme

Pinós; 3–4, photographs © Scott Murray; 5,

photographs © Estudio Carme Pinós; 6–8,

drawings by Scott Murray based on information

provided by the architects.

Netherlands Institute for Sound and Visionp. 154, photograph © Scott Murray; p. 155 and

figure 1, drawings courtesy Neutelings Riedijk

Architecten; 2–4, photographs © Scott Murray;

5–7, drawings by Scott Murray based on

information provided by the architects; 8–10,

photographs © Scott Murray.

Skirkanich Hallp. 162, photograph © Scott Murray; p. 163

and figure 1, drawings courtesy Tod Williams

Billie Tsien Architects; 2, photograph © Scott

Murray; 3, photograph courtesy the architects;


© Michael Moran; 6–8, drawings by Scott

Murray based on information provided by

263Illustration Credits

One Omotesandop. 100, photograph © Botond Bognar; p. 101,

drawing courtesy Kengo Kuma and Associates;

figure 1, photograph © Kengo Kuma and

Associates; 2, photograph © Botond Bognar;

3, drawings courtesy the architects;

4, photograph © Kengo Kuma and Associates;


information provided by the architects.

William J. Clinton Presidential Centerp. 106, photograph © Scott Murray; p. 107,

drawing courtesy Polshek Partnership

Architects; figures 1–2, courtesy the architects;

3–5, photographs © Scott Murray; 6–8,



Green-Wood Mausoleump. 112, photograph © Scott Murray; p. 113,

drawing courtesy Platt Byard Dovell White;

figures 1–3, photographs © Scott Murray;

4, drawing courtesy the architects; 5–7,



LVMH Osakap. 118, photograph © Botond Bognar; p. 119

and figures 1–2, drawings courtesy Kengo Kuma

and Associates; 3–4, photographs © Kengo

Kuma and Associates; 5–7, drawings by Scott


architect; 8, photograph © Kengo Kuma and

Associates; 9–10, photographs © Botond Bognar.

Seattle Public Libraryp. 126, photograph © Scott Murray; p. 127

and figures 1–2, drawing courtesy Office for

Metropolitan Architects and LMN Architects;

3, photograph © Lara Swimmer/Esto; 4–6,

photographs © Scott Murray; 7–9, drawings

by Scott Murray based on information


The Nelson-Atkins Museum of Artp. 198, photograph © Michael Robinson/Esto;

p. 199, drawing courtesy Steven Holl

Architects; figure 1, photograph © Scott Murray;

2–3, photographs © Steven Holl Architects,

courtesy Chris McVoy; 4–6, drawings by Scott


architects; 7, drawing courtesy the architects;

8–10, photographs © Scott Murray.

The New York Times Buildingp. 206, photograph © Scott Murray; p. 207

and figure 1, courtesy Renzo Piano Building

Workshop and FXFOWLE Architects;

2, photograph © David Sundberg/Esto;


© Nic Lehoux; 5–7, drawings by Scott Murray


architects; 8, photograph © David Sundberg/

Esto; 9, photograph © Scott Murray.

Spertus Institute of Jewish Studiesp. 214, photograph by William Zbaren ©

Krueck + Sexton Architects; p. 215 and figure

1, drawings by Krueck + Sexton Architects;

2, photograph by William Zbaren © Krueck +

Sexton Architects; 3–5, photographs © Scott

Murray; 6–8, drawings by Scott Murray based

on information provided by the architects;

9, William Zbaren © Krueck + Sexton

Architects; 10–12, courtesy the architects.

United States Federal Buildingp. 222, photograph © Scott Murray;

p. 223, drawing courtesy Morphosis; figure 1,

photograph © Tim Griffith/Esto; 2–3,

photographs © Scott Murray; 4–6, drawings

by Scott Murray based on information

provided by the architects; 7–9, photographs

© Scott Murray; 10, photograph by

Steve Proehl © Morphosis.

Yale Sculpture Buildingp. 230, photograph © Scott Murray; p. 231,

drawing courtesy KieranTimberlake Associates;

figures 1–2, photograph © Enzo Figueres; 3–4,

photograph © Scott Murray; 5–7, drawings by

Scott Murray based on information provided by

the architects.

Cathedral of Christ the Lightp. 236, photograph © Scott Murray; p. 237,

drawing courtesy Skidmore, Owings and

Merrill; figure 1–4, photograph © Scott Murray;


information provided by the architects;

8, drawing courtesy the architects; 9–11,

photograph © Scott Murray; 12, rendering

courtesy the architects.

100 Eleventh Avenuep. 244, image © dbox/Ateliers Jean Nouvel;

p. 245, drawing courtesy Ateliers Jean Nouvel;

figure 1, image © dbox/Ateliers Jean Nouvel;

2, photograph © Scott Murray; 3–4, image

© Ateliers Jean Nouvel; 5–7, drawings by

Scott Murray based on information provided

by the architects.

166 Perry Streetp. 250, image © ArchPartners/courtesy

Asymptote; p. 254, drawing © Asymptote;

figure 1, photograph © Asymptote; 2,

photograph © Scott Murray; 3–5, image

© ArchPartners/courtesy Asymptote;


information provided by the architects.

264Illustration Credits

Contemporary Curtain Wall Architecture

Documents

Transcript of Contemporary Curtain Wall Architecture