Spirit in the sky
Work has at last begun on Norman Foster's 'erotic gherkin'. Prepare to fall in love, says Jonathan Glancey
Monday April 16, 2001
The Guardian
A new wave of tall buildings is about to hit our cities. Do we need them? Will we come to love them as Americans rightly do the Empire State and Chrysler buildings? Maybe. But only if they turn out to be more subtle and special than the structures that bloomed so awkwardly in previous decades.
Sixties office towers, in particular, tended to be selfish things, exercises in corporate self-aggrandisement or symbols of developers' might. The new towers must connect with city life, rather than rise up from the pavements like massive closed books.
Enter the Swiss-Re building, rather stupidly nicknamed the "erotic gherkin". This is the 40-floor, 590ft office tower designed by Foster and Partners for the Swiss Reinsurance Company and dogged by controversy almost since the plans were completed. It is at last beginning to rise on the site of the former Baltic Exchange in the City of London.
The hole in the ground here comes courtesy of the IRA, which blew the old building to bits in 1992. The new structure promises to be one of the most distinctive towers yet built. What the company did not want was a bland, ecologically and socially irresponsible block; what it is getting is a very special building, where the latest in computer-aided design has been matched to an acute environmental awareness.
The shape of the Swiss-Re tower may look odd at first glance, but it grows on you as you begin to understand it. As it rises up over the City skyline, the tower tapers. The top is a cone. This reduces the visual bulk of what is, by any standards, a massive building. In addition, in wind-tunnel tests the shape proved to be aerodynamically efficient. This may not seem important - office blocks, after all, are not expected to fly - yet it is. Too many four-square office towers generate vicious downdrafts on windy days, making them unpleasant and even dangerous to walk past.
Moreover, the wind-load on slab-sided towers demands heavy-duty structural engineering. Because the wind will flow around Swiss-Re like air over and under a plane's wing, currents will be swept away from and well above pavement level; and because they will caress rather than buffet the building, the structure can be made lighter than conventional towers. This a lightweight, diagonally braced steel and aluminium frame connected internally to a central concrete core containing lifts.
There is a further advantage, and this one is great for the several thousand people who will work here. Air currents will be drawn into vents spun gently up and through the office floors. Since the windows will open (a real luxury for today's office workers), the Foster tower will therefore rely to a very limited degree on air-conditioning. Stale air will be exhausted into the tower's spiralling atria, or "sky gardens", where it will be re-oxygenated by trees and plants. The Swiss-Re will be as permeable as an emmenthal cheese.
Because the building will need little in the way of air-con equipment, its roof will be glazed and entirely free of the usual unsightly clutter. In fact, the top floors are to be a glamorous restaurant and bar. At this stage there can be no guarantee that these will be open to the public, but Swiss-Re is working on the idea. Let's hope it happens. Otherwise, public access will be via a two-floor shopping gallery at the base of the tower, which will rise from a new public plaza with trees, all-year open-air cafes and low walls designed to double up as benches. In summer, the walls of the tower above them will open up like some giant pinecone as windows lever outwards. From day to day, hour to hour, in fact, the skin of the building will change its appearance: the fall of light and shadow will never be quite the same.
Back inside, the tower promises encouraging working conditions for Swiss-Re staff. Aside from the fresh air, office floors are not stacked one on top of the other. Instead, they spiral up the inside of the tower following the "sky gardens", each of which is an atrium six floors high. What Swiss-Re wanted from the start was a building that connected staff rather than separated them. The idea here, is that most of the best ideas in the course of a working day stem from staff meeting casually on stairs, by water-dispensers, anywhere away from desks and computer screens.
The computer-aided design employed by Foster's team, alongside the engineers Ove Arup and Partners, is known as parametric modelling. It is intriguing to sit alongside the architects and to see how this tool, familiar to designers of the next generation of airliners, can offer structural and design options at supersonic speed while instantaneously reckoning the cost implications of extending a floor here or raising the height of an atrium there. In no way does this digital wizardry reduce the architects' role.
For all the logic behind the form and planning of Swiss-Re, it was still the architects' desire to shape a special building that looked like no other. Will we come to love it? Let's hope so. But what we must do is learn to demand that any new tall building in our city centres be as painstakingly and imaginatively designed as this.