Earthscraper

When Ray Sterling emerges from his seventh-floor office at the University of Minnesota here, he steps into a splash of sunlight and glances out a window to peruse the world outside.

Such a view might not seem unusual, except Dr. Sterling's office happens to be seven floors below ground.

He is one of the occupants of the university's new Civil and Mineral Engineering Building - a subterranean ''skyscraper'' that is pushing ahead the art of earth-sheltered architecture.

While not novel for its depth - a few buildings burrow farther than the 110 feet, or 10 stories, this one does - the structure incorporates several innovative lighting and design ideas.

These are aimed at dispelling any notions that living and working below ground need appeal only to moles. More than that, the ''earthscraper'' is a bold statement that architecture today should dovetail with, rather than dominate, the natural surroundings.

The roots of earth-sheltered construction run deep. Man has lived in underground hideaways for centuries in China, Turkey, and Spain. They have also become popular alternatives in Canada, Scandanavia, and parts of Europe and Asia (80 percent of the land in South Korea, for instance, is hilly, making it suitable for easy-to-build abodes).

The United States has long flirted with the concept, too. As many as 5,000 homes across the country now burrow into berms or hills. In Kansas City, several industrial enterprises inhabit a series of huge limestone caverns. Another 200 or so earth-covered commercial buildings have been built.

But in recent years the move to basement buildings has slowed down in the US. Stable oil prices have dampened one of the chief reasons for going underground: to shave energy costs. The other big motive, to save on space and avoid blocking the view of other buildings, remains though.

The $16.7 million building here accomplishes both - and then some. Ninety-five percent of the office, classroom, and laboratory complex lies underground. The brick and salmon-colored portion that doesn't pokes up unobstrusively between campus buildings. Because the ground temperature in Minneapolis is 55 degrees (F.) year round - even in obstinate January - architects figure the building's energy tab is 30 to 40 percent less a year than it would be for a comparable above-ground structure.

What makes the building particularly unusual, however, is the way it pipes natural light and street scenes down to the deepest levels. Consider, first, the lighting. One system captures sunlight in two mirrors that track the sun from a diamond-shaped cupola on the roof. These ''heliostats'' relay the light through a series of lenses and mirrors down a narrow shaft to the lowest (seventh) level. There it emerges through an opening in the ceiling, illuming an office area. The experimental system only works when the sun is out. But eventually architects want to bounce artifical light down the shaft for use on overcast days. The rationale: light from one source is more efficient than putting up dozens of individual bulbs.

The idea of tapping reflected light isn't new. The ancient Egyptians bounced sunlight into underground spaces while preparing tombs. But architects believe the modern incarnation being tested here could revolutionize lighting in buildings, buried or not.

''This is a whole new technology - one built on the delivery of light instead of the delivery of electricity that is transformed into light,'' says David Bennett, the architect and a partner in the firm of BRW Architects here. ''This system is like the first airplane.''

A second solar system goes farther in splashing daylight around the entombed edifice. This one is ''passive:'' It collects sunlight in a ribbon of stationary mirrors on the roof and bounces it through a skylight on the first floor. Mirrors then direct it to the cavernous materials structural laboratory, a five-story room running down the middle of the building. On sunny days the system throws enough light to cast sharp shadows. Even when there are clouds outside, little artificial light is needed inside.

Perhaps the most unusual feature of the building, though, is a 132-foot ''periscope'' that brings a street's-eye view to the lowest level. Believed to be the world's biggest, the periscope transmits a three-dimensional image of the outside world to a 2-by-3-foot window on the seventh level. Result: a room with a view 110-feet below ground.

Geology played a big part in shaping the building. The top two floors were carved out of loose glacial till. Beneath that lies a 30-foot shelf of limestone , which serves as a vibration-free foundation for the structure's laboratory and a roof for the two basement floors. These rooms were mined out of soft sandstone and are reached by stairs and elevators that plunge down a tubelike core. Other unusual features:

* A special drainage system designed to alleviate a stubborn problem in underground buildings: water seepage. One tool: a metal ''rain roof'' bolted to the limestone that acts as a giant eave.

* A ''Trombe wall'' solar-heating system that helps warm the big structure's lab. It consists of a series of water-filled cylinders that, during certain times of the year, collect heat in the day and release it into the building at night.

* A system for cooling computers that draws its refrigerant from the surrounding water table.

The chief contribution of all this, besides being a working campus building, may lie in its symbolic value of the potential of underground architecture.

''The building serves as a prototype for mined space development - something that people can see,'' says Dr. Sterling, director of the Underground Space Center, a university research group. The silver-thatched Bennett goes further. He sees it as a first step in a ''post-industrial architecture'' stressing cooperation instead of confrontation with the environment. His argument: Cheap resources and modern know-how have allowed man to impose his own style, often through brute force, on nature. This is why the same building design is seen in Minneapolis as in Denver.

Yet he sees new technology and a heightened environmental sensitivity spawning a movement where specific buildings will respond to specific locations. Earth-sheltered structures are one reflection of this. So are high-rises yet to be designed that sport different ''skins:'' for instance, one side made of sunlight-absorbing glass and the other thick masonry to fend off arctic winds.

The industrial age, he says, ''invented a whole new architecture the style of which represented the opportunity technology provided.'' The forces shaping tomorrow's buildings will be ecology and comfort. Pausing for a moment, Bennett glances around his creation here. ''This,'' he says flatly, ''is a different vision of the world.''

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