One Million Square Feet Of Glass

Joseph Paxton's original, 1851 Crystal Palace had nearly one million square feet of glass.

Our long love affair with light, and windows: The 1851 Crystal Palace sparked a desire for glass that continues to evolve. It was a brilliant spectacle and light years ahead of its time. “To anyone arriving at Hyde Park, the first sight of the Crystal Palace, floating above the trees, sparkling in sunshine, would have been a moment of knee-weakening splendor,” writes Bill Bryson in At Home,  a history of the world told through accounts of private life.  “… the idea of strolling through cubic acres of airy light inside a building was dazzling — indeed, giddying,” he says of the massive structure built in 1851 in London, England.

The Crystal Palace, designed by Sir Joseph Paxton and assembled in just five months, boasted almost one million square feet of glass and covered 7.7 hectares. It was the world’s largest building, erected for the first world’s fair, and marked a major milestone in the evolution of architectural glass. But darkness eventually descended on the Palace as it fell into financial ruin and burned to the ground in 1936.

Still, the door had opened on our love affair with light. Crystal Palaces sprang up around the world, including Picton, Ont., where a glass-and-wood structure built at the fairgrounds in 1887 is the only North American survivor. With windows on all sides of its cruciform plan, it proved a tempting target for vandals and spent 40 years boarded up until plastic sheeting replaced glass during restoration in the 1990s.

Though less splendiferous than London’s Crystal Palace, copy-cat versions all aimed to let maximum sun shine in. Construction of these glass-walled wonders was helped by two developments in the mid-1800s: cutting-edge technology that boosted the cheap production of sheet glass, and Britain’s abolishment of crippling window and glass taxes. Before that, people often bricked up their windows rather than put in expensive glass.

The story of windows through the ages is an illuminating one. Imagine moving day in the 16th century, for example, when you packed them up to take with you. Or consider the dilemma of trial witnesses testifying pre-1890s when judges deemed window glass too wavy to allow an accurate view of events.

Architectural historian Shannon Kyles praises the "irregularities" in her 1830s sash windows. At one time, courts rejected testimony of witnesses describing events seen through a window because the glass was too wavy.

But one man’s distortion is another woman’s delight, as Shannon Kyles gazes through the “irregularities” of her 1830s sash windows at the trees beyond. “I just love windows!” declares the architectural historian. Her Regency-style cottage, in Prince Edward County, has at least 20 that she took pains to preserve when she moved and rebuilt the house four years ago. “Loads of glass is wonderful,” says Kyles. “You can stand in a room in the middle of winter and still be comfortable — and you can see in four directions.”

She’s so enamoured of “lovely old windows” that she’s building an entire room out of them. And she’s even willing to pick up other people’s discards if the glass has imperfections or is crown or leaded.

Early window panes were made from crown glass that was blown and spun, causing a circular pattern in the centre. “People are just tossing them,” Kyles complains about old windows. “I have seen some fabulous original Arts and Crafts windows head to the landfills. It’s unbelievable.”

She takes on the notion that new vinyl-framed double- or triple-glazing is more energy-efficient. Properly restored old windows fitted with a storm are actually more energy-efficient than new ones, maintains Kyles, who’s made a video offering proof. She and other heritage conservationists would like to see the government offer tax incentives to restore, rather than replace, historic windows.

As an architectural feature, they shed light on society’s collective psyche, according to Kyles, who teaches architecture at Hamilton’s Mohawk College and explains building styles on her website, ontarioarchitecture.com. Back in the 14th and 15th centuries, house windows were placed high up for security reasons, she says. But now, “there’s glass on every side and floor because people aren’t afraid of someone just barging in and killing them.”

Architect Philip Johnson's innovative Glass house, built in New Canaan, Conn., in 1949.

That message is crystal clear in late American architect Philip Johnson’s famous Glass House, built in 1949 in New Canaan, Conn. With its fishbowl-like façade and open plan, the rectangular residence hides nothing from the outside world. In recent decades, glass walls have taken an upward turn as condo towers continue to sprout across the GTA skyline. But what goes up on those vertical crystal palaces has occasionally come down, in the form of glass showers.

Several times in recent years, downtown pedestrians have dodged pieces of balcony panels or outer windows that spontaneously shattered. Last fall, three class action lawsuits by hundreds of condo residents who lost the use of their balconies were given the green light to proceed after a dozen glass panes from their highrises plummeted to the street. Other incidents involved residential floors above the Shangri-La Hotel on University Ave. and the Four Seasons Hotel in Yorkville.

While these cases made headlines because of their location, falling glass isn’t new, says an engineer who’s studied the phenomenon for 30 years. Spontaneous breakage can occur in the first few years of a building’s life and only in fully tempered glass affected by a combination of factors such as temperature cycles and the presence of tiny imperfections, says Mark Brook, a partner at BVDA Façade Engineering.

Annealed glass, used in house windows, and heat-strengthened glass, used for large panes in commercial buildings, aren’t affected, he says. The strongest type, fully tempered glass that breaks into tiny cubes, is used in places that are susceptible to impact. Brook forecasts more — though not widespread — glass showers as young buildings settle in. “It’s highly unlikely it will be raining down for the next 10 years,” says Brook, who investigated some of the publicized incidents.

Most of the new towers going up now use laminated glass, made of two bonded layers that hold together when broken, he adds.  A window of opportunity, perhaps, for the crystal palaces of tomorrow?

Glass Rules

Glass rules our cities, for better and worse: Architects love glass, sometimes with a passion. Its unique qualities - transparency, reflectivity, the ability both to divide and unify space - are alluring. Of course, both passion and glass benefit from tempering. Many recently built high-rise office and apartment buildings in New York, Chicago and other cities sport taut, glazed skins. Sometimes the pattern of vertical and horizontal lines, the ultra-thin joints between rectangular glass panels, is the only articulation of facades soaring skyward.

Architects' continuing love affair with glass is evident even in downtown D.C., where skyscraping is outlawed. A number of recently constructed projects - for example new office buildings at 1999 K Street NW, (pictured below) and 801 17th Street N.W. (pictured left) - are sheathed entirely with glass. Large buildings with systematically composed, all-glass curtain walls can look quite elegant, like giant, scaleless cubic sculptures. A taut glass skin with crisp, minimalist detailing can reveal not only a building's structure and purity of form, but also its illuminated interior. It's akin to enveloping a building's skeleton with plastic wrap.

State-of-the-art glass and curtain wall technology makes this feasible. Sealed panels of double and sometimes triple layers of glass, separated by argon-filled cavities, insulate very well thermally while reflecting or absorbing unwanted radiation. Patterns on glass surfaces can be etched or applied using baked-on, ultra-thin layers of ceramic - known as "frit" - to filter daylight and reduce solar heat gain while creating decorative imagery. A glass facade can even be "green" by allowing daylight to pour into the interior, reducing daytime electric lighting needs.

Today, enormous sheets of glass can be manufactured. Laminated with reinforcing films, glass can be used structurally as beams and floor panels. Mullions, the framing that supports glass curtain walls, can themselves be made of glass. Meanwhile aluminum and stainless steel mullions have become less visible. Modern glass skins can be supported with hardware and structural supports attached only to the interior of glass panels, which can directly abut other panels separated by only a thin strip of sealant.

Glass is stable and impermeable. By contrast, concrete and masonry are porous materials that crack, absorb moisture and dirt, and eventually deteriorate after many freeze-thaw cycles. Metal can warp, deform, rust and react chemically with other substances. Painted materials need regular repainting. Durable glass can last indefinitely and requires little more than periodic cleaning. Glass has been around for centuries. In medieval churches, stained-glass windows were ornamental and spiritual as well as utilitarian, providing ethereal illumination along with biblical narrative. Window glass in some of Europe's palaces, civic buildings and housing dates back to the middle ages.

With the 19th century Industrial Revolution, glass-making technology and its architectural potential advanced rapidly. That potential was demonstrated most dramatically when Joseph Paxton, a British engineer, designed an enormous exhibition pavilion in a London park for the 1851 World Exposition (pictured left). Dubbed the Crystal Palace, the pavilion consisted of a cast iron skeleton covered totally with glass. A public sensation and technical tour-de-force, it made indoors feel like outdoors and expressed the alluring magic of transparency.

Architects were increasingly fascinated by the notion of transparent, all-glass buildings. In 1919 and 1920, as Chicago architects were constructing America's first high-rise, curtain wall buildings, Germany's Ludwig Mies van der Rohe (pictured) envisioned and crafted models of hypothetical 20- and 30-story skyscrapers clad totally in glass. Amazingly prescient, his unrealized designs look like buildings currently being constructed. But pulling a scaleless glass skin from a building's parapet down to a city sidewalk is aesthetically and functionally questionable. The bottom floors of an urban building, those first few dozen feet - two to three stories - rising from street level, demand different treatment than the many stories farther up.

Building entrances and canopies, along with storefront windows and doors of retail shops, cafes and restaurants, should occupy and animate the base of downtown buildings. Signage and lighting also must be part of the design of a building's base. Sidewalk level is where the public most directly comes in contact with architecture. This is where pedestrians become most aware of the visual and tactile qualities of a building's materials and details.

Thus to fulfill its streetscape obligations, the taut skin of a glass-clad urban building needs to change near the street level. To a facade's visual transparency must be added transparency of movement provided by welcoming entries. Transformation of the facade and skin may be accomplished using only glass, but it also may entail use of additional materials. In either case, the compositional challenge is making the transformation seem natural and integral to the overall design rather than appearing tacked on or retrofitted.

The quality of a work of architecture ultimately is not assured by use of glass or any other material. Rather it depends on the compositional talent and imagination of the designer and the artistry with which materials, whatever they might be, are assembled to make architectural form.

Roger K. Lewis is a practicing architect and a professor emeritus of architecture at the University of Maryland.