Skyscrapers and Environment

　　In the late 1960's, many people in North America turned their attention

　　to environmental problems, and new steel-and-glass skyscrapers were widely

　　criticized. Ecologists pointed out that a cluster of tall buildings in a

　　city often overburdens public transportation and parking lot capacities.

　　Skyscrapers are also lavish consumers, and wasters, of electric power. In

　　one recent year, the addition of 17 million square feet of skyscraper

　　office space in New York City raised the peak daily demand for electricity

　　by 120, 000 kilowatts -- enough to supply the entire city of Albany, New

　　York, for a day.

　　Glass-walled skyscrapers can be especially wasteful. The heat loss (or

　　gain) through a wall of half-inch plate glass is more than ten times

　　that through a typical masonry wall filled with insulation board. To

　　lessen the strain on heating and air-conditioning equipment, builders of

　　skyscrapers have begun to use double-glazed panels of glass, and reflective

　　glasses coated with silver or gold mirror films that reduce glare

　　as well as heat gain. However, mirror-walled skyscrapers raise the

　　temperature of the surrounding air and affect neighboring buildings.

　　Skyscrapers put a severe strain on a city's sanitation facilities, too. If

　　fully occupied, the two World Trade Center towers in New York City would

　　alone generate 2.25 million gallons of raw sewage each year -- as much as a

　　city the size of Stanford, Connecticut, which has a population of more than

　　109, 000.