Architecture - Diller Scofidio and Renfro Have Inflatable Plans at Hirshhorn - NYTimes.com I've never stepped onto the National Mall without feeling a mix of emotions - reverence, a flash of national solidarity, a feeling of loss - but pure delight has never been one of them. Diller Scofidio & Renfro A plan for the Hirshhorn calls for an inflatable structure that pokes through the building's top and side, on the National Mall. Images from Diller Scofidio & Renfro The planned Hirshhorn addition would have a lounge protruding into the Mall and an auditorium in the building's central court. That may soon change. For the last several months the newly appointed director of the Hirshhorn Museum and Sculpture Garden, Richard Koshalek, has been quietly at work on a plan to erect a 145-foot-tall inflatable meeting hall that would swell out of the top of the internal courtyard of the museum, which sits on the Mall midway between the White House and the Capitol. Designed by the New York firm Diller Scofidio & Renfro, the translucent fabric structure, which would be installed twice a year, for May and October, and be packed away in storage the rest of the time, would transform one of the most somber buildings on the mall into a luminous pop landmark. It could be the most uplifting work of civic architecture built in the capital since I. M. Pei completed his East Building of the National Gallery of Art more than 30 years ago. But it is what the project is intended to house, and to represent, that has the potential to shake up Washington. For decades government power brokers have dismissed much of contemporary culture as a playground for elites. Mr. Koshalek's vision would challenge that mentality by using performing arts, film series and conferences to foster a wide-ranging public debate on cultural values. Mr. Koshalek, who is known for his bubbly enthusiasm, has been a champion of architectural causes since his days as the director of the Museum of Contemporary Art, Los Angeles, in the late 1990s, when he helped lead the drive to build the Walt Disney Concert Hall. Later he worked behind the scenes with the city's government agencies and cultural institutions to hire respected architects for their new buildings rather than the kind of politically connected firms that were then the norm. He arrived at the Hirshhorn last April with a dual agenda: to raise the museum's national profile and to put Washington in closer touch with creative life around it. Within weeks he was promoting his vision to legislators, museum directors and foreign cultural attachés. Yet the museum he took over offered its own set of challenges. Completed in 1974, the building was one of the last major projects designed by Gordon Bunshaft, a pillar of American postwar Modernism. Its gray, drum-shaped exterior, propped up on four massive concrete legs, has a bunker-like appearance that seems to keep the city at a distance. The cylindrical courtyard, which is slightly off center in an obvious attempt to offset its formal purity, has the eerie stillness of a set from an Antonioni film. And since the Hirshhorn is part of the Smithsonian Institution and stands on such sacred ground, any permanent addition would require the approval of the notoriously conservative Fine Arts Commission and the National Capital Planning Commission, a process that could take years. The beauty of a temporary structure, Mr. Koshalek realized, is that he would only need to consult with the members of his own board. The budget would be around $5 million, a relatively paltry sum by the standards of recent museum expansions, even in today's rough economic climate. And the design's extreme flexibility - it can be blown up at a moment's notice, and the interior can be easily reconfigured - could allow the museum to respond nimbly to cultural issues of the moment. Worst case, if it turned out that people hated it, it could be packed away forever. The architects imagine the installation process as a performance piece in itself, something like watching event organizers blow up the balloons for the Macy's Thanksgiving Day Parade. Two refrigerator-size air pumps would be used to inflate the baby-blue structure, which would fill the entire four-story courtyard and bulge out of the top. A smaller, globulelike form would swell out of the bottom of the building to create a public lounge overlooking the mall. The aura of lightness - of a building that seems ready to float off into the sky - is counteracted by the structural systems that hold the addition in place. A gigantic tube of water, like an inner tube, encircles the interior of the structure to weigh it down. A series of big steel cables, tethered to the inner tube at one end and to a roof-level truss at the other, would wrap several times around the translucent form as it rises through the core of the building, making it resemble an uneven stack of donuts or an act of ritual bondage. Most visitors would enter the structure through a short, tube-shaped corridor located at the seam between the lounge and the main courtyard space. In the current version of the design, which is still being refined, the lounge's translucent blue skin becomes progressively more transparent at the base, so that visitors will be able to see out into the mall. The inner tube that would anchor this room's outer edge serves as an informal bench. The main hall, by contrast, would be slightly more formal. A temporary stage would be built over the courtyard's off-center fountain, with up to 1,000 seats arranged in a semicircle around it. Further up, a few transparent areas in the fabric would allow visitors occasional views of people up in the galleries. Given the height of the interior, the architects might consider adding one or two levels of balcony space, which would add richness to the design and take advantage of what is now a four-story-tall void. Will Mr. Koshalek's vision succeed? It's too soon to say. The project could become something Washington has never had: a real democratic forum for the debate of cultural issues as varied as, say, Hollywood morals and the impact of fundamentalism on the arts. It could also, of course, become a political punching bag. The structure itself, if it is ever built, will be part of a long tradition of architects seeking to tap into the energy and accessibility of popular culture. It includes projects like Archigram's 1969 Instant City, which was partly inspired by the cheap, ethereal structures of postwar Los Angeles, and Peter Cook's 1968 Ideas Circus, an informal think tank enclosed underneath a big dome that could be packed up in trucks and moved from city to city. Like those earlier models, the Hirshhorn project is informal, egalitarian and free of conventional hierarchies. It aims to provide an elastic framework for a more inclusive culture, one that is in a continual process of reinvention. At a time when Washington is focused on practical issues of survival, from health care to the war in Afghanistan, it would also provide a sanctuary for speculating on the nature of the civilization we are building.