During the last 20 years, the revival of the covered, interior atrium has been catalyzed primarily by social, economic and technological circumstances in the world of building design and real estate development.

In the 1950s, developers discovered that people liked shopping in large retail shopping centers organized around enclosed atria or pedestrian malls. Reasonable facsimiles of older downtown shopping districts, malls are like streets lined by shops and stores, except that they have roofs, often glazed to admit natural daylight while keeping out the elements.

And shopping center owners, managers, designers and tenants also realized that people came to do more than shop. Malls were the new town squares of suburbia, places in which to hang out, to stroll, to meet friends and to socialize. By the 1960s, the enclosed shopping mall with its interior streetscape was firmly established as an undeniable social, commercial and architectural prototype destined for worldwide popularity.

Meanwhile, architect John Portman was concocting the Hyatt Regency Hotel in Atlanta's Peachtree Center, begun in 1961. He must have concluded that something was missing in most functionalist, commercial architecture, with its conscious rejection of embellishment and exuberance. This was especially problematic for hotels, a building type historically characterized by lobby, dining and ballroom spaces richly decorated to impart feelings of comfort, luxury and grandeur.

Portman saw the atrium as the modernist answer, not only because it could be big and breathtaking, but also because it was potentially cost-effective and more profitable.

He reasoned that wrapping hundreds of hotel rooms around a dramatic space would transform the hotel experience totally, both for guests and everyone else. The atrium's novelty and architectural bravado, its transparency and scale, would be irresistible enticements. People would spend considerable money to sleep in such a hotel, knowing that, come morning, they could walk out into the atrium, ride down a glass elevator and have breakfast at its base while watching others do likewise.

Obviously, this was not the cheapest way to build a hotel. Just ask the people at Holiday Inn or Ramada. But the additional capital costs involved in building the atrium -- primarily attributable to the roof and wall systems, ventilation system, and fire- and smoke-control systems -- appeared reasonable and justified in comparison with total development costs for comparable space. Moreover, much atrium-related construction makes use of (or replaces) components of the building that would have to be built even without an atrium.

Most important, Portman and his associates knew that the financial bottom line was not dependent on initial capital cost alone, but rather on the potential income that the capital investment could generate. If a Hyatt Regency, with its spectacular atrium, could achieve a higher room-occupancy percentage and command a higher room rate, then the first costs associated with the atrium would more than pay for themselves during the hotel's operating years. In the eyes of the investors, not to build the atrium would have been no savings at all.

About the same time in New York City, a building was going up which, in its own aesthetic way, would add to the atrium momentum engendered by shopping malls and hotels. The Ford Foundation building, designed by Roche/Dinkeloo in the mid-1960s, was a 12-story structure, half of whose volume consisted of an atrium garden. This influential building, although not developed for commercial or profit-making purposes, was a portent, and not just in Manhattan.

The west and north sides of the Ford Foundation building's square plan are occupied by offices forming an "L," and the atrium fills the rest of the square abutting the sidewalk and street. Therefore, most of the street facade consists of the south-facing glass-and-steel atrium wall. Office windows lining the west and north walls of the atrium space consequently have views of the garden below, filled with lush vegetation, and of the street beyond.

As in Portman's hotels, the Ford Foundation atrium provides a dramatic and picturesque spatial focus, although it serves only as a passive space for entry, a space to look at and through, rather than one to be occupied and used.

But it made a small building very special, very noticeable and very newsworthy in a city dominated by towering high-risers and wind-swept plazas.

Yet, Hyatt hotels, Ford Foundation buildings and other atrium edifices could not be constructed were it not for innovations in fire-safety design. Until the 1960s, common design practice, and most building codes, precluded uninterrupted atrium spaces in multi-storied, high-occupancy buildings.

The theory was that, if a fire started in or adjacent to an enclosed atrium, natural drafts induced by the fire's heated and expanding gases would rapidly permeate the entire building with suffocating smoke. Moreover, an atrium could facilitate the spread of the fire itself from one floor level to another.

Consider what occurred here in Washington on May 13, 1977, at the International Monetary Fund headquarters building at 19th and G streets NW, designed by Vincent Kling five years earlier.

The IMF building was one of Washington's first and largest atrium office buildings. It rises 13 stories and encompasses a 100-by-140-foot, 11-story skylighted atrium surrounded on all sides by windowed offices.

After working hours, a small fire started in a 10th-floor, 10-by-15-foot office. The fire's heat soon caused the office's atrium window glass to break. Within minutes, tens of thousands of cubic feet of smoke began filling the upper part of the atrium.

Automatic smoke detectors signaled six roof vents to open. Only two worked. Smoke continued filling the atrium faster than it could be evacuated, eventually pushing all the way down to the atrium's bottom levels.

Unfortunately, the atrium's mechanical ventilation and smoke-exhaust system had been turned off at the end of the day. The building engineer had left, and firefighters were unable to operate the system equipment.

Eventually, the four unopened roof vents were opened manually, and portable fans were brought in to blow out the smoke, but not before several hundred thousand dollars in damage occurred. Thus, a fire in one 150-square-foot office generated enough smoke to fill an atrium with a volume of more than 1.5 million cubic feet, even though the fire never spread.

Despite such risks, the impetus to create atria has led fire-safety experts to develop and continually refine standards by which atria can be incorporated safely in tall buildings. Specific design issues involve combustibility of materials, smoke and fire detection, control and evacuation of smoke, suppression of fire, and means of egress for building occupants.

The National Fire Protection Association now requires that automatic, mechanically operated smoke-exhaust systems be in operation at all times in atrium buildings. They must be completely covered by sprinklers, and smoke and fire detectors throughout such buildings must automatically activate alarm and fire-department-alert systems and in-building fire and smoke-control systems. No more than three adjacent floor levels can be open to the atrium; otherwise, a one-hour fire separation is required between surrounding spaces and the atrium.

Adequate escape routes and fire stairs must provide alternative, fire-protected means of egress from all points of occupancy in atrium buildings, just as in other buildings. The mandatory use of incombustible materials (steel, aluminum, concrete, masonry, glass) must be complemented by minimizing use of flammable furnishings -- trim, decorative fabrics, furniture.

Perhaps atrium buildings are now safer than conventional buildings, for an atrium serves as a giant plenum and reservoir from which great volumes of smoke can be evacuated quickly. Of course, as with airplanes, this theory is only as good as the machines and men who maintain them. We trust that they do.

NEXT: Atria as theater.