Shigeru Ban stares into the camera, stoic, revealing the occasional hint of a half-smile. “The lights are bright,” he says, as a photographer shoots multi­ple frames of him sitting against the wall of a conference room in Manhattan’s Kitano Hotel. It’s six o’clock on a Monday evening in August. Ban, a Japanese architect acclaimed for his poetic sensibility and use of nontraditional building materials like paper tubes—“an old-school Modernist with a poet’s touch and an engineer’s inventiveness,” is how Michael Kimmelman, The New York Times’ new chief architecture critic, once described him—has just flown in that morning from his Paris office.

He spent the day with his New York–based partner, Dean Maltz, discussing a new commission—his first foray into restoration work, he says. Tomorrow he’s flying to Colorado for a meeting about his design of the new 30,000-square-foot Aspen Art Museum. Right now, though, he’s braving the spotlights to discuss what he considers the more socially significant aspect of his legacy: his humanitarian projects.

Ban, Hon. FAIA, has developed a reputation as a post-disaster design specialist, a kind of global-age architect-cum-philanthropist who flies into disaster zones—sometimes invited, sometimes not—and spearheads projects that help small groups of refugees and victims not served by government agencies or NGOs. He’s among a select but growing cadre of architects who balance high-end design work for big-budget, high-profile clients (his current commissions include the Goa Hotel in India and the Beach Club in Lebanon) with humanitarian projects, such as his temporary shelters for earthquake victims in Haiti, Turkey, and India. “Underlying all of Ban’s work is an extraordinary architectural sensibility,” says Michael Maltzan, FAIA, whose Los Angeles firm has designed both low-income housing for Skid Row residents and performing arts centers for elite universities. “The work he does for emergency or disaster situations is just as inventive and strong and beautiful as [the rest of his portfolio].”

To be sure, Ban’s projects have suggested the potential for good design to benefit victims reeling amid post-disaster chaos. But his ultimate quest—to revolutionize the quality of post-disaster housing—raises the question of how effective high-end architects can be as de facto relief workers.

Photo shoot finished, Ban sits down in the Kitano’s wood-paneled café for a coffee. He’s dressed, as always, in all black: loafers, a button-down shirt with a Mandarin collar, and a calculator watch. A ballpoint pen is tucked below one of the buttons on his shirt lapel. He has the faint wisp of a mustache and goatee, a soft, round face, and wavy black hair that confers a professorial air. Is he tired? No, he says, dismissing the question with a wave of the hand. Working primarily from Paris, he flies back to his Tokyo office twice a month now because of his ongoing post-earthquake work in Japan. Time zones, apparently, have become more suggestion than rule.

Ban was born in 1957 in Tokyo. His father, now retired, worked for Toyota. His mother designs womens’ clothes and employs a team of seamstresses in her studio. As a boy, Ban wanted to be a carpenter, after watching workmen renovate his mother’s house. She turns 81 this year and still runs her business on the second floor of her building, renting out the rest of the space to Ban, who uses it for his Tokyo office. He smiles, says he’s often late paying the rent: “I’m not very interested in money. My partners take care of the business part.”

Ban came to the United States to study under the late John Hejduk at Cooper Union, after reading about his innovative experiments with brightly colored cubes and grids. One of Hejduk’s assignments: Write a poem. It proved a formative lesson for Ban, who can’t recall what he drafted in his limited English but vividly remembers the takeaway: writing a poem—achieving a deeper meaning by structuring a minimum of words—and designing a building are parallel pursuits.

Toshiko Mori, FAIA, founding principal of her epony­mous New York firm, was a professor at Cooper Union at the time. “He was a very motivated student, entrepreneurial and energetic,” she says. Hejduk’s concern for social justice, his ideas about architects’ engagement with a social contract, resonated with Ban, whose subsequent humanitarian work took those abstract principles and found a real-world expression for them, she says.

Ban’s epiphany—his career-altering or, perhaps, career-expanding moment—came after the Rwandan genocide in 1994, long before MoMA had curated exhibits about humanitarian-inspired architecture or glossy hardbacks featured such projects. He had started his own firm in 1985, at the precocious age of 28, but had quickly grown disillusioned. “Mainly we were working for privileged people,” he says. “Their power and money are invisible, so they want to have monumental architecture to show their power and money to the public.”

By then, Ban had started experimenting with paper as a building material, which is surprisingly strong when rolled into tubes—and, he realized, an economical and practical solution for designing temporary housing for refugees. Ban approached the United Nations High Commissioner for Refugees. Rwanda victims at the time were given makeshift aluminum-pole-and-plastic-sheet contraptions. But refugees often sold the aluminum and then cut down trees to build their shelters. Why not use paper tubes instead? Ban designed a prototype, got U.N. approval, and had more than 50 units manufactured.

A bevy of projects followed, including his design of paper log houses (the foundations made from plastic Kirin beer crates filled with sandbags) and a church following the 1995 earthquake in Kobe, Japan; a model house in post-Katrina New Orleans for the Make It Right Foundation; temporary schools in post-earthquake China in 2008; and a paper-tube concert hall, which opened in May, after the 2009 earthquake in L’Aquila, Italy.

Most of those projects relied on Ban’s loosely organized nonprofit, the Voluntary Architects Network, which brings together students and local architects after a crisis. (“Students used to say they wanted to be starchitects and work for developers,” he says; now they want to work on his humanitarian projects.) His modus operandi: parachute in, get a project started, and then have students complete it, which necessitates that the design be simple. Local architects, meanwhile, help him to incorporate regional building materials and to respect cultural mores.