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University of Hawai‘i Students Create Cool Roofs Using Native Moss

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University of Hawaiʻi at Mānoa
University of Hawaiʻi at Mānoa students designed a sustainable roof using native moss. Their project is seen here at the Magoon Research Station in Mānoa Valley.

Two University of Hawaiʻi at Mānoa students have developed a sustainable roof design using native moss and recycled fishing net.

Shelby Cerwonka and Jasmine Reighard wanted their project to tackle climate change on a household level.

The pair used recycled fishing nets collected by Sustainable Coastlines Hawai‘i, and they collected the native pincushion moss found along the Koʻolau mountains in Windward Oʻahu.

The team built four structures and measured their temperatures over a three-month period. They found the structures with moss roofs were cooler by about 5 degrees Fahrenheit.

“We wanted to create something that was lightweight, that was affordable and that could still serve in a plethora of environmental solutions," Cerwonka said. "And moss was a perfect candidate of biological matter since it doesn't require roots and I'm trying to think of another way to solve another issue was coming up with using the recycled fishnet as that alternative soil medium because it's so readily available.”

Cerwonka and Reighard graduated in the spring. They hope to publish their findings in a scientific journal in the next few months.

They eventually want to commercialize the innovation.

During the trial phase, the most costly expense was a waterproof tarp used between the structure and the moss. The moss was propagated and the recycled fishing net was donated. Another cost would be installation and watering.

"But the great thing about moss is that it doesn't require a lot of water, which a lot of green roofs do," Reighard said. "With moss, they can go a long time without water. I think we've gone maybe three weeks without watering them and they go into a dormant state, which basically they turn white. But once you water them again they go back to green and keep doing what they're doing."

But they believe the biggest hurdle will be automating the process of transforming the recycled fishing nets into mats for the moss. By hand, it took them three months to make two mats on their test structures.

The project received more than $9,000 from the UH Mānoa Undergraduate Research Opportunities Program.

Jason Ubay is a news editor at Hawaiʻi Public Radio. Send your story ideas to him at
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