<div xmlns="http://www.w3.org/1999/xhtml">Zhang Yue, a developer who is using a prefab system to build the world’s tallest tower, Sky City, in Changsha, China, has constructed a test slice (lower left) of stories 165 to 173.</div><div xmlns="http://www.w3.org/1999/xhtml"><br/></div>

Zhang Yue, a developer who is using a prefab system to build the world’s tallest tower, Sky City, in Changsha, China, has constructed a test slice (lower left) of stories 165 to 173.


Remember those perfectly trim and modern modular designs that were supposed to revolutionize the home-building industry, and that seemed to appear every other month on the cover of certain shelter magazines?

Well, the prefab residential dream is still out there, battered but surviving, and seeming to cede none of the rhetorical high ground. Not long ago I saw an item about Pharrell Williams, the hip-hop impresario, teaming up with Zaha Hadid, Hon. FAIA, on a new line of prefab houses. (“There’s a collaboration I’m working with Zaha Hadid,” Williams told an interviewer. “We’re touring around with the idea of a prefab for a house.”) And then I came across a magazine essay about how “the factory-built home is gaining traction,” and immediately was whisked back to those heady days of the early aughts, when every architecture buff I knew was shopping for a vacant lot to put up a sleek and affordable three-bedroom by Marmol Radziner or Michelle Kaufmann.

The truth, however, is that the aspiration at the core of all those stories about the modern prefab house—that it was a prototype for a new and cheaper way to get stylish architecture built at a mass scale—never really came close to being fulfilled. Like the Case Study Houses a half-century earlier, this 21st-century version of democratized High Architecture could never crack the byzantine, if profitable, code of the home-building industry, which continues to deliver tens of thousands of stick-built residences every year to subdivisions around the country.

It’s not so much that there is not a substantial market in the United States for neo-modern prefabs; it’s that the potential home buyers for those designs tend to live in major metropolitan areas where the available land is both very expensive and not flat. And it’s cheap, flat land that makes any new home-building enterprise succeed at scale.

But a funny thing happened on the way to prefab’s seeming demise: Modular construction began going vertical in a pretty significant and architecturally ambitious way. It turns out that while modular systems still don’t make a lot of economic sense for one-off projects aimed at design-savvy urbanites, there are some real efficiencies in applying them to taller urban buildings, particularly multifamily residential projects.

Two high-profile projects now being built—an apartment tower by SHoP Architects in Brooklyn, N.Y., and a residential mid-rise by Michael Maltzan, FAIA, for the Skid Row Housing Trust in Los Angeles—use a modular system, the basics of which are already commonplace in the construction of roadside hotels and other quick-rising commercial architecture across the country. In each case, the architects say, going modular has modestly brought down costs while dramatically accelerating the construction process.

In China, meanwhile, a supremely ambitious real-estate developer and entrepreneur named Zhang Yue, who made his fortune outfitting new buildings with air-conditioning units in Shanghai, Beijing, and other cities, is hoping to build the world’s tallest tower in just four months by relying on a proprietary prefab system. His Sky City project—meant to rise 202 stories, beating out the Burj Khalifa in Dubai for the title of tallest on Earth by 30 feet—has received a windfall of coverage in the Western press, much of it justifiably skeptical.

Zhang Yue, a developer who is using a prefab system to build the worlds tallest tower, Sky City, in Changsha, China, has constructed a test slice (lower left) of stories 165 to 173.

A rendering of Sky City in Changsha, China.

Credit: Broad Sustainable Building


The start of construction has been delayed several times, and engineering experts have cast doubt on Zhang’s claim that using a prefab system will slice building costs on the tower in half, compared with traditional methods, to an estimated $1.5 billion. Bureaucrats at the highest levels of the Chinese government in Beijing are said to be reviewing the building plans, or possibly holding them hostage. After scandals involving the shoddy construction of schools and other buildings, and a high-speed-rail crash in 2011 that killed 40 passengers, the Chinese have grown more cautious about record-breaking projects like Zhang’s.

Still, having covered the stop-and-start progress of the CCTV tower in Beijing, by Rem Koolhaas and Ole Scheeren of the Office for Metropolitan Architecture, I’m not ready to write off Sky City altogether. There were several moments when CCTV seemed definitively dead and buried, felled by some of the same concerns inside China about overreach and hubris that now shroud plans for Zhang’s tower. Uncertainty and even grave doubts about a major building’s prospects seem to be a fundamental part of the design process in contemporary China.

Sky City, designed by a group of in-house designers at Zhang’s new modular spinoff company, Broad Sustainable Building, will certainly have none of CCTV’s singular architectural power. It is indeed almost un-designed, a simple toy-like stack of prefab units that, if built, would contain 4,450 apartments for 30,000 residents.

Instead of the architecture, it is the height of the building paired with a hyper-ambitious construction schedule that has drawn attention to Zhang’s quixotic project, slated for a site on the outskirts of Changsha, a smog-choked city of 7 million inhabitants. He has said that the basic site work is complete, and that he’ll be able to build the 202 stories in about 120 days. The Burj Khalifa, the current record-holder, took six years to build, and the tower set to surpass both it and Sky City, the kilometer-tall Kingdom Tower in Jeddah, Saudi Arabia, by Adrian Smith + Gordon Gill Architecture, will likely take at least as long.

Broad City has already proved the efficacy of its approach, at least for shorter towers, by building a 30-story apartment building in 15 days and a 15-story building in six days. Time-lapse videos of those towers zooming to completion have been watched by architects around the world, many of them with a combination of disdain at the generically forgettable design and envy at what it must be like to work in a country where the pace of construction seems to be accelerating by the month.

B2, SHoP&#39;s modular residential tower under construction in Atlantic Yards in Brooklyn.

B2, SHoP's modular residential tower under construction in Atlantic Yards in Brooklyn.

Credit: SHoP Architects


In Brooklyn, where SHoP took over developer Bruce Ratner’s controversial Atlantic Yards mega-project from Frank Gehry, FAIA’s office during the economic downturn, a modular approach’s appeal is also speed—and, just as important, a quieter and tidier kind of construction.

In collaboration with the firm Ellerbe Becket (now part of AECOM), SHoP designed the well-received Barclays Center for Forest City Ratner Companies and the Brooklyn Nets. Now comes the first residential phase of the project, consisting of three apartment towers ranging in height from 25 to 49 stories. The first one, now under construction, is known as B2 and will rise 32 stories; the subsequent ones are called B3 and B4. The towers will contain a total of 1,500 units, half of them earmarked for low- and middle-income residents. The other half will be market-rate rentals. They will be the tallest modular buildings ever completed.

Chris Sharples, AIA, one of SHoP’s founding principals, was careful to clarify in my interview with him some basic distinctions between modular and prefabricated building techniques. In modular towers like B2, entire sections—fully outfitted with appliances, cabinetry, lighting, and floor finishes—are built in a factory and then stacked on site. In prefab, it is panels or other parts that are delivered to a construction site, where they have to be assembled.

The difference can be crucial to the pace of construction and its efficiency. On the B2 tower, Sharples said, 60 percent of the work is being done in a factory, and 40 percent on site, trimming a 24-month construction timeline closer to 18 months. With that shorter timeline comes significant financial savings, since the carrying costs for construction loans are reduced.

With the second and third towers, SHoP hopes to push the ratio of factory-to-site time closer to 70-30 or even 80-20. And that brings benefits that have nothing to do with financing. Getting more of the construction work on a high-rise done in a factory, where the climate is predictable and everybody is working at ground level, means a safer job for trade workers, no small issue when you consider the dangerous history of high-rise building in New York and cities around the world. “The plumbers, the electricians, the drywallers are all working together on the mods, on the factory floor, instead of separating the trades out,” Sharples said.

A modular process also takes a lot of the mess and noise produced by construction out of the city—and out of people’s neighborhoods—and behind the walls of a factory. For a project like Atlantic Yards, which has been highly controversial in Brooklyn throughout its various phases, the importance of that shift would be tough to overstate.

Sharples also said, despite the news coming out of Changsha, the most efficient kind of modular tower might be in the low- to mid-rise category. “If you do super-tall, above 50 stories, say, you’ll need a brace frame,” he said. “If you’re shorter—if you’re around 20 stories—you can integrate that lateral frame into the mods. And there’s huge savings there.”

Michael Maltzans Star Apartments in Los Angeles, designed with 104 units for the Skid Row Housing Trust.

Michael Maltzan’s Star Apartments in Los Angeles, designed with 104 units for the Skid Row Housing Trust.

Credit: Michael Maltzan Architecture Inc.


Maltzan’s modular project, the Star Apartments, is, at six stories, even shorter. But by the standards of the Skid Row section of downtown L.A., home to one of the largest homeless populations in the U.S., this is vertical architecture. The project is a hybrid, combining the adaptive reuse of a small existing retail building with a podium above for community programs. Stacked in a zig-zag pattern above that is a collection of apartment modules—wood-framed units built in an Idaho factory—containing 104 studio apartments.

The method has cut construction time and therefore reduced carrying costs on the project. But as is the case in Brooklyn, the major appeal for Maltzan was the chance to move most of the construction and associated mess inside a factory. Since the Skid Row Housing Trust wanted—for a range of reasons—to keep the existing building on site and build around and above it, there was little room for a staging area for construction. Bringing the modules in by crane and dropping them atop the podium was a sort of necessary choreography, one that may become more common in L.A. as the city grows denser and less suburban.

Maltzan said the project required him to adjust the way he thinks about the design process. “You have to change your approach,” he said. “There’s no away around that. They do a mock-up of the unit early on, to test it. And at that moment you can see it fully in three dimensions and make corrections. But after that it’s done—it’s off to the races.”

Still, he added, that system, as nerve-wracking as it can be for architects used to tweaking their designs as they’re constructed, is the basis of modular’s financial appeal: “There’s no mystery to it. If you look at how manufacturing works in general, it is at its most cost-effective when it’s producing multiples.”

In the end, the biggest achievement in Maltzan’s project may be the way it demonstrates that modular buildings can have real, and even unorthodox, formal appeal. The Sky City tower has a kind of dumb simplicity, and SHoP’s Brooklyn towers, while a huge architectural step up from Changsha, will have a straightforward, unapologetically modular profile on the skyline.

Maltzan’s Skid Row effort, surprisingly enough, uses a modular approach to make the final product appear more designed—more architectural—rather than less. The uneven stacking of the apartment units, and how they seem to hover in the air like tilting cabs on a Ferris wheel, seems likely to guarantee that the building, when finished, will carry with it none of the stale air of the factory.