In 1973, more than 580,000 manufactured (or HUD-code) housing units were shipped and placed throughout the country, representing nearly one-third of all new homes built that year. The mobile-home industry’s next spike occurred in 1998, when 373,000 shipments that year made up 23% of all housing starts. By contrast, the nearly 52,000 HUD-code homes shipped in 2011 accounted for a mere 8.3% of the new-home market.
Despite the segment’s historically low numbers in recent years and annual market shares no greater than 9% dating back to at least 2006, architect James Guthrie thinks there’s only one thing missing from an equation that would revive production-level prefab to sustainable prominence: design.
“Everything else is in place to make prefab housing a success,” he says, specifically the segment’s existing manufacturing and distribution infrastructure, a viable business model, and a housing industry hungry for (and perhaps eventually mandated to provide) affordable, well-built, and resource-efficient options to conventional methods. “The market has accepted it at a certain level since the 1960s. Now it’s time to get architects involved.”
It’s not just talk. Guthrie’s firm, The Miletus Group in Rochester, Ind., offers both architectural services and prefab manufacturing capability from a 1970s-era, 40,000-square-foot facility. Guthrie retooled the plant for design-centric production modules and what he calls “architectural prototyping” to test and prove his concept.
The company also touts itself as the country’s first carbon-neutral prefab design-build firm, a goal attained by significantly reducing energy consumption and purchasing carbon offsets. “It wasn’t as onerous as I heard it would be,” says Guthrie of his two-year journey to achieve a net-zero carbon footprint per the AIA 2030 Commitment protocol.
Guthrie’s first foray into architectural prefab attacked the construction trailer market. Notoriously inefficient and uncomfortable, jobsite trailers account for about 100 million square feet of space nationwide.
Two years on the market, Guthrie’s re-engineered modules have cut energy bills for the 600-square-foot units by as much as 73% thanks to a tighter, insulated, and weather-resistant skin that’s still lightweight and within interstate highway shipping tolerances. “We addressed all six exposures, including the undercarriage, with available materials that were architecturally applied,” he says. “They don’t look much different, but they act entirely different.”
In addition to a better-built module, Guthrie advocates that prefab is inherently more resource efficient than conventional methods—a mantra that’s been echoed if not widely executed to date. “Factory precision is by definition less wasteful of raw materials,” he says. “Even if your goal isn’t green, the level of control and automation creates a building that is necessarily more efficient. Housing is the only industry that hasn’t embraced that concept.”
For architectural prefab to make inroads into housing, Guthrie looks forward to a game-changing, likely multifamily project like Murray Grove, a five-story, 30-unit apartment building in London, which had a profound impact on the European market upon its completion in 2000, in the wake of the Kyoto Protocol.
For that project, the architect required the use of factory-built prefab modules as the primary building system to achieve a combination of affordability and resource efficiency--not to mention a 27-week cycle time with scant construction waste.
“Murray Grove is a piece of architecture first,” says Guthrie, that leveraged an existing module from a hotel room manufacturer, a well-heeled supply chain, and a proven stacked-box building method. “They just tweaked it a little to create beautiful, affordable, and efficient workforce housing.”
That award-winning project legitimized prefab’s potential for well-designed affordable housing and inspired several other projects throughout Europe to follow suit—most recently a 805-unit, 24-story apartment building in Wolverhampton, U.K., that used stacked prefab modules to shave a year off the construction schedule.
In the U.S., Guthrie hopes that Atlantic Yards, a planned 34-story affordable housing project in Brooklyn, N.Y., adjacent to the new Nets basketball arena, serves the same purpose as Murray Place did in Europe more than a decade ago.
The project’s use of nearly 900 stacked modules is expected to cut costs and cycle time in half; more significantly, it would prove the viability of architectural prefab in North America. “You don’t need to reinvent the manufacturing process,” says Guthrie. “The guts are already there. Manufacturers and architects just need to talk to each other.”