University of Hawaii Students Create Cool Roofs Using Native Moss

Two students from the University of Hawaii at Mānoa 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 at the household level.

The pair used recycled fishing nets collected by Sustainable Coastlines Hawai’i, and they collected the native pincushion moss found along the Ko’olau Mountains in Windward O’ahu.

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

“We wanted to create something that was lightweight, affordable and could still serve a plethora of environmental solutions,” Cerwonka said. “And moss was a perfect candidate for biological material because it doesn’t need roots and I’m trying to come up with another way to solve another problem was to use the recycled fishing net as that alternative soil medium, because it is so easily available.

Cerwonka and Reighard graduated in the spring. In the coming months, they hope to publish their findings in a scientific journal.

They ultimately want to commercialize the innovation.

During the pilot phase, the most expensive expense was a waterproof tarp used between the structure and the moss. The moss was multiplied and the recycled fishing net was donated. Other costs include installation and watering.

“But the great thing about moss is that it doesn’t need a lot of water, which many green roofs do,” Reighard said. “With moss, they can go without water for a long time. I think we’ve kept them without water for maybe three weeks and they go into a dormant state, which basically turns white. But when you water them again, they turn green again and keep doing what they do.”

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 create two mats on their test structures.

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

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