In 1973 and 1974, the Arab oil embargo led to some unanticipated architectural results. The politically precipitated energy crisis quickly sensitized people to the amount and cost of energy consumed by buildings, mostly for heating, cooling and lighting.

Architects, engineers, developers, consumers and government policy makers alike all agreed that conserving energy could save money and, in the aggregate, decrease susceptibility to volatile world petroleum markets. Thus, over the past decade, energy consciousness began affecting American building design. How ironic that it was catalyzed by Arab cultures whose indigenous architecture always had been energy conscious in a natural, passive way.

Among the most conspicuous, aggressively energy-conscious buildings in Washington is Intelsat's headquarters building on Connecticut Avenue between Van Ness and Tilden streets NW. Like a transposed fragment of some dense Middle Eastern medina rendered in high tech, this assembly of glass-roofed, octagonal atria enclosed by octagonal office pods adds an alien but intriguing image to Washington's traditional cityscape.

John Andrews International, an Australian architectural firm, won the invited competition for Intelsat's design in 1980. The project's first phase called for a 600,000-square-foot building with two major, seemingly contradictory objectives. First, it was to be as energy efficient as possible. Second, it was to provide 70 percent of all office space with natural daylight.

Obliged to design a large, potentially massive building, Andrews wanted to fragment the project in some rational, geometric way to diminish its perceivable bulk and to achieve the daylighting objective. The pod-and-atrium plan was his solution. It creates extensive perimeter wall surface, some on the outside and some facing the atrium spaces on the interior.

The nearly 12-acre, sloping site included stands of mature deciduous trees on the northwest and southeast corners. By linking pod-and-atrium clusters diagonally, the complex could march up the hill and across the site from the northeast corner at Connecticut and Van Ness, leaving the wooded portions of the site at the other corners undisturbed for visual and energy reasons. In summer, breezes blowing through these trees could help cool the building.

To complete his diagram, Andrews pulled the fire stairs out of the pods and placed them in cylindrical, glass block and concrete towers ceremoniously standing guard at the entrances and in the spaces between pods. Contrary to first impressions, the stairs inside are rectangular, as required by code, not circular. Mechanical equipment is housed in aluminum-clad cylinders atop four of the stair towers.

While offices stretch around the naturally lighted perimeters of each pod, conference rooms and coffee closets occupy their lightless centers. Bathrooms and mechanical risers are situated in the joints between pods. Two of the atrium spaces have stairs and an elevator rising in their center; these are connected to joints between pods by overhead ridges.

Intelsat's passive-energy-conservation strategy is geared more to summer than winter. A combination of clear and reflective glass is incorporated in atrium skylights, depending on solar orientation. Tinted, reflective glass panels and tubular stainless steel form sun screens that cover the clear glass window walls. These keep out much of the summer sun's most intense, infrared radiation, while still permitting views to the sky and the landscape from the interior.

The exterior sun screens are held several feet away from the curtain wall so that summertime heat trapped between the sun screen and the wall can rise and ventilate away. On the other hand, the sun screen blocks wind in winter and presumably traps heat escaping from the building to create a warmer layer of air adjacent to the building skin.

Some winter sun, low in elevation, can enter the building through nonreflective portions of the glass atrium roofs and the building's aluminum and glass curtain wall facades. However, most wintertime heating is produced within the building itself.

Perhaps the most ingenious passive cooling tactic involves ponds on the roofs of low-lying utility spaces adjacent to the buiding. When the outside temperature is moderate and the humidity not too high, air already cooled by the nearby trees blows across these ponds. There it is cooled further and then, by convection, drawn directly into the bottom of the atrium. Exhaust fans in the atrium roof expel warm air, inducing continuous inflow of cooler air from below.

Geoff Willing, the project architect, said that the atrium spaces themselves almost never need air conditioning. This, in turn, means that all the offices facing an atrium need little or no air conditioning, a substantial saving in energy consumption.

The active, mechanical energy systems at Intelsat, designed with the assistance of the Virginia office of the Benham Group, are based on "cogeneration," heat recovery and storage, and heat pumping. With 100,000 square feet of heat-producing computer space, Intelsat simultaneously heats and cools itself. Also, it has its own gas turbine and diesel electric power generators.

With its assortment of heat pumps, chillers, hot- and cold-water storage tanks, and electric power generators, plus computerized monitoring and control systems deciding what, when and where, Intelsat can cut its energy consumption by: Generating its own electricity at peak hours of usage, thereby reducing the rate it pays Potomac Electric Power Co. Recovering waste heat produced by computer equipment, electric lighting, generators and other sources, which then may be used directly or stored for later use. Using recovered or stored heat to drive chillers producing cool water needed to absorb or recover more heat. Cool water also can be stored for later use.

What's the bottom line on all this energy conservation? Published reports claim that Intelsat needs about 70,000 British thermal units, a measurement of heat, per square foot each year for heating, cooling, lighting, domestic hot water, computers and other equipment. By comparison, a Benham Group study of 40 government and 51 private office buildings showed an average consumption of 75,000 BTUs per square foot. Without passive and active conservation, this energy would have to be purchased.

But the projected energy saving at Intelsat comes to 40,500 BTUs per square foot, a dramatic 58 percent of the total needed for operation. Therefore, its theoretical utility bill would be for only about 30,000 BTUs per square foot per year. This represents an estimated annual energy cost reduction of $174,000.

There are, of course, additional capital costs associated with making an energy-efficient building. Intelsat's construction costs totaled $60 million, about one-third of which was for mechanical, electrical and building automation work. The atrium roofs accounted for nearly $5 million, while the sun screens and facade glazing totaled more than $3 million. Over time, Intelsat hopes that savings in utility costs will more than offset extra capital costs incurred for energy conservation.

Learning how and why Intelsat was designed may not change your opinion of the building's aesthetic merits. But it may help you understand it better, both as an energy-conserving artifact and, perhaps, as a visual analogy to the communications satellites it produces and commands.

NEXT: The dwelling environment