Skyscrapers Are Proliferating But Not Always Reaching Great Heights

Cities are going up in the world, and not necessarily in a good way. At the AAAS Annual Meeting, a 15 February seminar on the future of cities posed the big question: should cities become more densely populated, or should people be more widely dispersed?

For Antony Wood, who heads the Council on Tall Buildings and Urban Habitat in Chicago, there isn't much doubt: America's great export, the skyscraper, is multiplying and growing taller at the same time. What he called the "rectilinear air-conditioned box" is springing up everywhere, simply because there are more people with more demands for somewhere to live. Fifty-three percent of the population is now urban, and this proportion is expected to grow along with the absolute numbers of people in need of new living space. The issue has become how to accommodate the millions now swelling the cities.

"Do they go into denser, more concentrated cities, or do they go into the traditional American model of a city, which is a dispersed city, with a dense downtown working core, with an ever expanding suburb?" Wood asked.

Tall buildings are getting taller -- the tallest is 828 meters (about 2,700 feet) tall -- and they have exploded in number around the world. In the 1960s globally one or two 200-meter buildings were built each year around the world. Now, 60 to 90 such buildings are being completed. Even as recently as 1990, 80 percent of the world's tallest buildings were in North America. The figure is now 20 percent and falling rapidly. Most of the growth has been in Asia and the Middle East. Within a few years 80 percent will be in Asia. In 2000, 85 percent of tall buildings were offices, but now this is only 43 percent, due to a huge shift to residential housing. Structural materials have changed as well, from steel to concrete and composite construction.

"However, is this a good thing? I actually believe that 95 percent of tall buildings around the world are terrible, terrible pieces of design, " Wood said. The same design has been adopted without reference to the varieties of climate, environment and tradition, and without attention to the needs of the people who might have to live in them. "We are homogenizing the planet," he said.

A strong case can be made against tall buildings, which take more energy to build, maintain and manage. They create local downdrafts and pools of shadow; they are essentially antisocial environments with no open accessible spaces for recreation; they are vulnerable to power failure, and access to the remainder of the world requires a journey to the ground floor, Wood explained.

"If we only concentrate on the single building, we will always be a long way from making sustainable cities. It is not about the single building," he said. "It is about concentration of people and infrastructure. It is also about transport."  Hong Kong is one of the world's most sustainable cities, at certain levels: walk out of the door and there is a variety of transport. In Houston, residents who want a loaf of bread must get into their car and drive several miles. So the challenge is to find acceptable living space for the nine billion people expected on the planet by 2050, the majority of whom will live in the cities. This requires new thinking and new experiments in vertical living.

In the last 10 years Wood and students have developed a set of principles for the design of new buildings. For instance, they should vary in height. New and multiple functions should be introduced. Most tall buildings are for residential, office or hotel purposes, but why not introduce vertical farming, to produce food at the point of need? What about recreational space for children and residents? Sky gardens at every level, which offer access to light and natural ventilation? There should be vegetation at every level; the world needs to "greenify" its cities, according to Wood. And above all, architects need to connect their new tall buildings with sky bridges. "It is absolutely ridiculous that we are growing ever more vertical without bringing in the horizontal," Wood said.