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A deep dive into Maine's response, one county at a time.

Why 3D printing could advance two of Maine's big goals: climate action and affordable housing

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Advanced Structures and Composites Center
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University of Maine
The University of Maine's Advanced Structures and Composites Center has the world's largest polymer 3D printer, which is being used to make test modules for a 3D-printed home.

It's loud inside the University of Maine's Advanced Structures and Composites Center, where students and engineers hover over noisy lab equipment and large ceiling fans whirl overhead. And that's without the world's largest 3D printer running.

Habib Dagher, the center's executive director, says the printer is down at the moment. But once it's back up and running, it will print test modules for the center's latest endeavor — a 3D printed house.

This story is part of our series "Climate Driven: A deep dive into Maine's response, one county at a time."

In Maine, there's a shortage of nearly 20,000 affordable homes for low-income households, according the National Low Income Housing Coalition. And nationwide, that number is closer to 7 million.

Dagher says this project could eventually alleviate those challenges. At least, that's the goal.

He motions to a module sitting on a platform near the printer and points out the beginning of what he says will eventually be a curved roof.

It's difficult to imagine that this structure, which almost resembles extra thick, heavy duty cardboard, could one day be the floor, walls and roof of someone's house.

"Once this module is done then we can go inside and finish it," Dagher says. "If it's the kitchen, you can actually put the kitchen cabinets in, you can start running the wiring in it, and so on and so forth. And then once all the modules have what they have in them, so when they arrive to the site, it's just a matter of putting the modules together and plugging things in."

It sounds simple, but Dagher says if his team can pull it off, it'll be after years of trial and error. So far the initial tests are promising, and the university believes it's well on its way to building the world's first-ever bio-based, 3D printed house.

There have been efforts all across world and in the United States to 3D print new homes. But Dagher says the vast majority of those homes are printed with concrete, and a 3D printer is typically used only to lay the home's foundation and maybe the walls.

"We're printing the whole house," he says. "We're not printing it with concrete; we're printing it with wood, which is a renewable resource that has a much better carbon footprint than concrete does. And if it's renewable resource we can help capture carbon, it also becomes a carbon storage capability."

Traditional building construction accounts for about 40% of the world's carbon emissions.

But the University of Maine has spent years experimenting with a more sustainable material that can be fed through the printer. The material used for this 3D printed home is made from wood flour — essentially the waste left over from a sawmill — and mixed together with a binder made from corn, Dagher says.

The material could be a win-win, both in achieving net-zero or even net-negative carbon emissions for building construction, and in providing another business opportunity for Maine's forest products industry.

"We're printing at a very large scale," says Susan MacKay, a senior research and development manager at the composites center. "So there's an opportunity to divert forest residues and forest products into a high-volume application. That's very important because Maine historically has served the paper industry. And you can't replace the paper industry, but you can complement it with other value-added, large scale types of industries."

The material is also recyclable. Large 3D printed objects can be ground down and the material can be reused to print something else. Dagher says his team is testing how often it can be reused, potentially as many as five times.

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Advanced Structures and Composites Center
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University of Maine
The university's 3D printer can print 150,000 pounds per hour. Habib Dagher, executive director of the Advanced Structures and Composites Center, said his team is working to expand the printer's capacity to 500,000 pounds an hour by the fall.

Beyond the environmental benefits, the university's 3D printed homes could also help Maine reach its affordable housing goals.

MaineHousing wants to build 1,000 new affordable housing units each year. At that rate, it would take 20 years to bridge the state's present affordable housing gap of 20,000 units.

Mark Wiesendanger, development director for MaineHousing, says home construction has become increasingly difficult to pull off, even though the state has more money for it than even before.

"That's great, but the problem is construction costs have gone up so much that those dollars didn't go as far as we initially thought they would," he says. "And there are so many projects under construction right now that nothing is happening quickly."

But with this kind of 3D printing technology, Dagher says the entire home is printed and filled inside a factory, meaning developers don't have to worry about construction delays in the winter.

"Imagine a day where you need a 600-foot low-income home and here's the design, and you can email the drawings here to the factory," he says. "The factory, within a week, can print what you need here, or less, and deliver it to the site."

MaineHousing worked with the university and a private architecture firm to design a prototype for a single-family home that meets the agency's construction, accessibility and energy standards. So far, Wiesendanger says initial tests show the model is resistant to insects and tolerant of heat swings.

Dagher is cautiously optimistic. The university plans to print four other modules and put them together.

"We're going to set [the home] right behind our lab and make sure that we get it out there before the end of the year, so it goes through a very nice Maine winter, with sensors on it," Dagher says. "[We're going to] make sure it works and it does what it's supposed to do. We're going to learn a lot from that experience."

Even if the weather testing is successful, it'll take time before small neighborhoods of 3D printed, affordable homes are popping up around Maine, Wiesendanger says.

"I see the biggest barrier right now is that this industry ... it doesn't exist," he says. "We're really building the ship as we're flying it."

The 3D printers themselves are expensive, and many other organizations will have to enter the market to make the homes affordable for those who need them, Wiesendanger says. The University of Maine relies on federal grant money and partnerships with the U.S. Energy Department's Oak Ridge National Laboratory to get these projects off the ground.

"But this is really something that could change the way we build housing throughout the world," he adds. "And I think it's a great opportunity for Maine to start a new industry and be leaders in it."

Dagher stresses there are constant setbacks in this research. But he remains hopeful that his team can prove 3D printing works, and that someday it could be part of the solution to both the climate and affordable housing crises.