BA VI, VIETNAM (NYTIMES) - Just below a hilltop pagoda, steel frames the size of two-car garages were popping up on a bluff that overlooked a valley of electric-green rice paddies.
They were prefabricated homes designed by Vietnamese architect Vo Trong Nghia, and the construction team said it was impressed by the speed of its own handiwork: nearly one frame hoisted per hour, including smoke breaks, and largely without power tools.
"Looks like Legos, and it's easy to install," said Nguyen Duc Trung, a project supervisor.
"Much easier than building a normal house," one of the workers, Le Van Dung, said between drags of a cigarette. Far cheaper, too: a small fraction of the US$35,000 (S$48,330) that he said it would cost to build a home in his northern Vietnamese village.
Known as "S Houses", these prefab structures going up here in Ba Vi, about 30 miles (48 km) from Vietnam's capital, Hanoi, are iterations of a prototype that Nghia has been honing since about 2013. They will serve as the living quarters for a new Buddhist meditation centre.
But Nghia says that his plan is to mass-manufacture this portable, easy-to-assemble design for people in slums, remote areas or refugee camps around the world, beginning later this year, all for the starting price - US$1,500 - of about two iPhones.
"We architects always do designs for clients with lots of money, but there are a lot of needs" in poor communities as well, said Nghia, whose work often transposes Japanese-style minimalism to a Southeast Asian context. His staff says it is fielding preliminary inquiries from prospective buyers as far away as Peru, Nigeria, Vanuatu, Yemen, Iraq and Syria.
Nghia, 40, said that the S House was designed to last at least 30 years and to withstand severe tropical storms like the ones his "super poor" family once experienced in their central Vietnamese farming village. "That's really important," he said. Otherwise, villagers will "spend their lives building houses over and over and over."
Nghia is the latest high-profile architect to design an inexpensive, prefabricated home as an antidote to urban sprawl, mass displacement or natural disasters. Experts say the S House is one of several "humanitarian" or "social" architecture projects worldwide that highlight a rising social consciousness in the profession at a moment when the estimated number of displaced people worldwide - 65.6 million last year - is the highest since the aftermath of World War II.
Some of these projects are recognised as much for their form as their function. The Japanese architect Shigeru Ban designed shelters from recyclable paper tubes for victims of violence and natural disasters, for example, while the Chilean architect Alejandro Aravena has pioneered what he calls "incremental" social housing projects, in which residents buy half of a two-story home at a state-subsidised rate and complete it when and how they can.
Other designs are known for their high-profile sponsors. The Sweden-based Better Shelter project, for instance, partnered with the United Nations High Commissioner for Refugees and the furniture giant Ikea to mass-produce an emergency shelter with a solar panel, UV-protective roofing and siding, and parts that can be individually replaced.
These and other projects have generally been well received by design professionals. Ban and Aravena have both recently won the Pritzker Prize, architecture's top honor, and the Museum of Modern Art in New York last year selected a Better Shelter unit for its permanent collection and featured it in an exhibition.
Some critics say, however, that high-profile humanitarian architecture often ignores the complexities of housing policy and finance, as well as local variations in climate, building materials and aesthetic tastes.
Chang Jiat Hwee, an assistant professor of architecture at the National University of Singapore and the author of "A Genealogy of Tropical Architecture: Colonial Networks, Nature and Technoscience", said the notion of using prefabricated dwellings to solve housing problems in the global South was pioneered by Europeans in the 19th century and became especially prevalent in the 1950s. But the projects have tended to fail, then and now, he added, because they took a universalist approach that ignored local particulars.
Chang said he wondered if the S House project could avoid the same pitfalls. "Vo Trong Nghia is a very good architect and his firm has designed some really nice single-family houses," he said. "But I think designing a prototype for mass housing presents an entirely different set of challenges."
Pham Thuy Loan, the vice president of the Vietnam National Institute of Architecture, said it might not be practical to sell S Houses across much of northern Vietnam because people there would see a steel-frame design as too radical a departure from a traditional concrete one. They could perhaps imagine Nghia's creation as "someone else's house," she said, but not their own.
But people in rural areas of southern Vietnam might be amenable because some there are less committed to traditional aesthetics, Loan added. The S House could also potentially serve as temporary housing, she said, for rural migrants who work in industrial zones near Hanoi.
Nghia said the S House would fit many different environments, in part because its US$1,500 frame can be purchased alone and clad in whatever local materials are available. A full package would cost between US$2,000 and US$3,000 and include steel-lattice walls and a corrugated roof.
The S House is suitable for remote areas because no single component weighs more than 110 pounds (49.8 kg), he said, and its design could also be modified to suit local conditions - higher ceilings for hotter climates, for example, or bigger units for communities with larger families.
Nghia said that he planned to scale up production to meet whatever demand materialises, either from individuals or institutions, and that he would offer to sell S Houses to the United Nations, at cost, as refugee shelters. (The S stands for "strong, sustainable and steel".) Meanwhile, he said, he would be watching to see how the 38 new S Houses in Ba Vi hold up during their first test: an eight-week silent meditation course that he planned to attend.
Each house will have a thatch roof, four beds and no air-conditioning. "I'll know what the problems are" after so much time for reflection, he said with a laugh. "But I believe it will be really comfortable."
On a recent afternoon in Ba Vi, a group of Buddhists involved in the meditation centre project watched as construction workers in blue Vo Trong Nghia jackets hoisted S House frames into place under intense sunshine.
One member of the group, Nguyen Thao, a Buddhist nun from southern Vietnam who wore a long maroon robe, said she looked forward to staying in the S House and would not mind its lack of luxurious amenities.
"It's good enough for us," Thao said with a bright smile, "because we live a simple lifestyle."