On any given night in the U.S., more than 500,000 of our fellow citizens sleep in a tent or homeless shelter, an abandoned building, on the sidewalk or in the back seat of their car.
Millions more live with friends or family members, while many of those fortunate enough to have roofs over their heads often subsist one day at a time, choosing between paying rent and buying food or medicine. The situation is untenable and inhumane, but solutions have been hard to come by.
No state or city is immune from the affordable housing crisis, notes Angelina Buzzelli, a communications specialist and market research analyst at the University of Maine’s Advanced Structures and Composites Center (ASCC) in Orono. “On a good year, we’ll see maybe five to six hundred new housing units in Maine, far less than the 20,000 needed in our state alone. It’s a dire situation.”
The solution seems simple enough: build more houses, and, if need be, subsidize their construction and subsequent ownership. But setting aside bitter political battles that would ensue from such a proposal, the housing industry is one of many struggling with the skilled worker shortage, never mind rising costs for everything from wood and concrete to drywall, electrical wiring and plumbing supplies.
Nor are these traditional building materials earth-friendly. “One of our objectives is to increase the use of sustainable sourced materials in housing,” adds Buzzelli’s colleague, Senior Research Engineer and Program Manager Scott Tomlinson. “For example, we have an extreme amount of bio-based cellulosic material—sawmill shavings—here in Maine. We’re working hard to incorporate that waste material into building structures, and do so in a scalable manner.”
Tomlinson is the engineer of record and lead designer for BioHome3D, which according to the team’s Aubin Case Study submission, is the world’s first fully bio-based, fully recyclable, highly insulated 3D-printed house. A collaboration between the U.S. Department of Energy’s Oak Ridge National Laboratory (ORNL) in Tennessee and the ASCC at the University of Maine (UMaine), the project is also supported by:
The Maine Technology Institute, which provides loans, grants and investments to innovative companies throughout the state.
Bangor-based engineering and architecture firm WBRC Inc., whose team contributed to the interior design and layout of the 3D-printed BioHome.
The Maine State Housing Authority (MaineHousing), which works to prevent homelessness through financial and administrative programs.
This hub-and-spoke program connects ORNL’s broad manufacturing and research capabilities with regional centers of excellence at the University of Maine in forest-derived biocomposites to bring new, sustainable and functional materials to the market. This synergy between diverse centers of excellence is vital to enable mainstream adoption of new technologies to achieve carbon neutrality.
“Our partnership with MaineHousing was one of the driving forces behind this initiative, but each organization played an important role in its success,” notes Buzzelli.
BioHome3D is the world’s first fully bio-based, fully recyclable, highly insulated 3D-printed house.
Halil Tekinalp is an ORNL senior research and development scientist with extensive experience in the 3D printing of polymer composites, and has been there since the project’s beginning—in fact, he literally helped lay some of the groundwork. Together with other team members, Tekinalp began looking for bio-based polymer feedstocks long before ORNL’s involvement with BioHome.
“We learned early on that large-scale 3D-printed structures are both stronger and less prone to warping when built with fibrous materials,” Tekinalp says. “Carbon fiber is a great option, but is expensive, not sustainable and has a very large carbon footprint, so we mixed bamboo fibers with PLA (polylactic acid), a biobased polymer feedstock. It turned out to be very effective.”
That’s an understatement. The team used a Big Area Additive Manufacturing (BAAM) fused filament fabrication (FFF) printer developed by ORNL and Cincinnati Inc.—one of the many advanced machine tools found in the U.S. Department of Energy’s Manufacturing Demonstration Facility (MDF) at ORNL.
The facility is home to the MDF Consortium, a nationwide group of collaborators working with ORNL to advance the state of the art in U.S. manufacturing technology under the guidance of DOE’s Advanced Manufacturing and Materials Technology Office. The group collaborated with New York-based SHoP Architects and other partners to produce an outdoor jellyfish-inspired pavilion (named Flotsam and Jetsam) for display at the 2016 DesignMiami expo.
Not surprisingly, the massive structures earned a Panerai Visionary Award and spent the next two years at the Miami Design District’s Jungle Plaza before being moved to the University of Nairobi in Kenya, where it remains to this day. “We used more than 10,000 pounds of bamboo-filled feedstock in those two builds,” says Tekinalp. “Seven years of sunlight and weather later, it is still standing strong.”
ORNL aimed to build on this success (pun intended) with its next project: a 3D-printed mold used to fabricate the rooftop for a large yacht. As before, one of the goals was to eliminate petroleum-based feedstocks in favor of green alternatives, which in this case brought them to another leader in this area, UMaine and its ASCC.
“Due to slowdowns in the paper mill industry over the past few decades, they were doing research into cellulose nanofiber (CNF) composites, and similar to our previous work, wanted to find ways to use them in place of carbon and glass fiber-filled polymers,” Tekinalp says.
Scott Tomlinson was one of those researchers. Due to his many years in structural engineering, infrastructure development and extensive experience with marine and energy applications, this was far from his first composite rodeo. “I spent a lot of time experimenting with composites and building prototypes of lightweight bridge girders, offshore floating wind turbines, and related projects,” he says. “But through it all, I wanted to figure out the best way to 3D print a house.”
Like his counterparts at ORNL, Tomlinson was well-equipped to do so. UMaine’s ASCC is home to the largest thermoplastic printer in the world, a custom-built Ingersoll MasterPrint 3X boasting X-Y-Z travels of 60 ft. x 22 ft. x 10 ft. (18.3 m x 6.7 m x 3 m), able to print up to 150 lbs. (68 kgs) per hour and equipped with a five-axis milling head for in-process machining. Between the massive machine and ASCC’s ongoing efforts in this area, UMaine earned three Guinness World Records in 2019: the world’s largest polymer 3D printer, largest solid 3D-printed object and largest 3D-printed boat. The latter is made of wood-based filament.
“Shortly before the award ceremony, we also printed an Army shelter, which we designed and built in just four days,” he says. “That small project helped illustrate the huge potential of 3D-printed homes, so when Oak Ridge reached out to us, we were more than ready.”
ASCC and ORNL signed a memorandum of understanding soon after, and the “hub-and-spoke” program was born. Tomlinson explains that “Oak Ridge has a ton of knowledge in additive manufacturing, and we have a ton of knowledge in cellulose reinforced thermoplastics.” The next step was how to leverage that combination.
And leverage it they did. Using cellulose-based biomaterials, they constructed a 600-sq-ft (55-sq-m), single-story dwelling made of four modules that join together via a patented 45° angle interface. After printing, each was insulated and pre-wired for electricity, then shipped to the building site for assembly. Two days later, the lights were on, the walls ready for artwork. The first 100% bio-based, 3D-printed home—one that meets all of Maine’s stringent building codes—had been built.
“Obviously, this was just the first step,” says Tekinalp. “We continue to optimize the design and manufacturing process, perform long-term environmental testing, and look for ways to incorporate additional functionality into the build—HVAC ducts, for example, and integrated plumbing lines—but the project has proven that we have a viable concept.”
Tomlinson agrees, noting that it’s a global concept. “Here in the Northeastern United States, we have plenty of wood fiber from the sawmills, but when we start a factory in Botswana, we could use waste from coffee plants, or coconut shavings in Ghana, sugarcane in India, and so on. The market is absolutely huge, as is the business case and, more importantly, the need for low-cost, earth-friendly housing that you can build quickly and easily.”
They’re well on their way to achieving that growth. As of this writing, ASCC was busy installing an even bigger 3D printer, a 500 lb/hour extrusion machine that provides twice the build length, nearly four times the width, and almost double the height of their MasterPrint. According to Tomlinson, this new printer—also from Ingersoll and dubbed the Factory of the Future 1.0—will turn the entire building into a print envelope.
“We don’t want to print a house every couple of months,” he says. “We want to print one every couple of days. That’s when the economies of scale start to make sense and we’ll be able to make a meaningful difference in the housing crisis. But to do that, we first need to drastically scale up our cellulose feedstock production, something our entire materials development group is working on. So yes, we’re just getting started, but I think I’m speaking for all of us when I say we’re very excited about the possibilities.”
