Ubiquitous green glass has doomed our city buildings to darkness

LISA ROCHON Saturday, March 15, 2008

A sickly green patina has washed over the glass towers of our cities.

It is the awful colour of hospital corridors and encroaching disease. Green-tinted glass has metastasized from Vancouver to Toronto to New York to Shanghai, dumbing down the exhilarating potential of the skyscraper, mortifying the skyline.

Once, not so long ago, the modern skyline was a robust, diverse composition with plenty of neo-gothic limestone towers and crisply edited modern high-rises. In Toronto (Toronto-Dominion Centre), Chicago (Lake Shore Drive Apartments) and New York (Seagram Building), the German architect Mies van der Rohe produced sheer cliffs of darkness. In Vancouver, the B.C. Electric Building (1957), now a condominium, was designed with a curtain wall of porcelain, steel and glass. At the height of glam-rock, there were flamboyant exercises in gold, from the Trump Tower (1983) in Manhattan to the Royal Bank Plaza (1976) in Toronto's downtown with each of its 14,000 windows coated with a layer of 24 karat gold.

The dynamic skyline belongs, apparently, to a bygone era. So does the ability of cities to present distinct versions of the metropolis to the world. What's sprouted in its place is the ubiquitous green (or icy blue) glass tower, a monolith and a formula that numbs our hopes for the 21st century skyline.

The reason? A glass tower provides better views of Vancouver's North Shore Mountains, as in the case of the Coal Harbour lands, now crowded with not-so-jolly green giants. Or, of neighbours who can now peek at each other way up high, as in the case of Toronto's Concord Adex development and those tinted towers lurking on the urban edges and closer to the waterfront. The see-through tower has turned ordinary citizens into consummate voyeurs.

To understand the impact of the green glass tower on human beings, I called James Carpenter, a New York-based glass designer who won a $500,000 MacArthur Foundation "genius" award in 2004 for his ability to sculpt light with glass. "Green glass has absolutely no response to the sky," he says.

"These towers are occupying the sky plane, but, because they have a very distinct colour of their own, they don't have much of a reflectivity to them. They're really quite dead."

The skyscraper creates an instant vertical community in the sky. But, increasingly, the glass tower has become a vertical community blinkered from the sky. This has not always been the way. When Mies van der Rohe designed the German pavilion in Barcelona (1929) for an international exhibition, he used glass that had been produced by rolling the material followed by the grinding and polishing of both sides. "It was absolutely dead flat with perfect reflections," says Carpenter. "It's so pure and so crisp in its reflectivity." In fact, when Mies sketched a glass skyscraper for the Friedrichstrasse competition in Berlin (1921), it was rendered as a perfectly glassy minimalist tower - part utopian, part romantic - not as a corpse of green.

There's nothing romantic about the average developer's budget, however.

Tinted glass is cheaper to buy than other clearer, crisper glass. That's because the glass that has swept the condominium market contains high levels of iron oxide, an impurity that exists in sand. The more iron you add to the glass the greener it becomes and the greater its ability to stop the transmission of infrared rays from the sun. The tint allows for the redirection of heat out of the building.

Tinted glass, which typically transmits only about 15 per cent of natural light, got kick-started in the 1970s as a response to the energy crisis. So, while it became less expensive to heat buildings, the green glass required far greater use of artificial lighting to compensate for the near elimination of natural daylight.

"What happened was the production of doomed-to-darkness buildings," says Carpenter. And, there is the common use these days of ultrathin glass, which is not thermally treated to resist extreme shifts in temperatures. It can break, he says, and "the cheaper glass gets very highly distorted and looks wrinkly. Light reflections become very uneven."
In Calgary, Vancouver and Toronto, in markets where even the most non-descript condominiums will find buyers, formulas of convention drive the way that towers are designed. "The client doesn't want the risk or can't take the time to incorporate new materials," says Toronto developer Julie Di Lorenzo. "Units have been sold so there is no pressure to experiment. It's the mentality of lemmings."

What colour is your city? For the sake of nostalgia, it's comforting to think that the colour of cities should derive strictly from a particular geography. Historically, architecture and the earth represented a seamless story, producing, for instance, the ochre hill towns of Dordogne, France, the golden colour of Rome and the red-brick Victorian neighbourhoods of Toronto. Even now, it is still possible to connect a white skyline to Pittsburgh, and Manhattan as a city divided between the presence and absence of light. "Uptown is white. Downtown is black. Darkness and light," says New York architect Fred Schwartz.

Meanwhile, despite the greening of Chicago, the windy city still hinges on a neutral palette of black, grey and white, says Blair Kamin, the Chicago Tribune's architecture critic. "It's an expression of Chicago's toughness, its seriousness, its Calvinistic work ethic. Tropical colours would look foolish in a no-nonsense, northern city like this."

The challenge these days is to express an architecture that is not only technologically advanced but enticing to the eye. A popular device these days, coloured spandrels inserted horizontally into a glass curtain wall is a nice touch, but it's hardly interactive. For works of transcendence in glass look to American architect Steven Holl, just appointed to design, with Canadian associates Bortolotto Design Architect, a district energy building to fuel the new West Donlands neighbourhood in Toronto.

Look, also, to New York's 7 World Trade Center (2006), a 52-storey glass tower of inspiring depth and mutability by James Carpenter Design Associates in collaboration with lead architect David Childs of Skidmore, Owings & Merrill. The tower's six-storey base presents an exterior skin of stainless steel fins and slightly angled prisms, the better to capture any ambient light that finds its way to street level while disguising a power station that sits behind its porous walls. The upper stories of the skyscraper feature sheets of ultra clear, low-iron glass that travel, remarkably, past the floor slabs of each storey, with recessed cavities of stainless steel operating like reflecting scuppers; in the end, the monolithic character of the tower is broken down, while tenants are allowed a seamless connection to the sky.

Take away the tint of the glass tower and we start to see the sky for what it is: a changing, subtle landscape. Heavy with weather, inspiration and difference.