February 24, 2012

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By Kathryn Kopchik

LEWISBURG, Pa. — Studying jackrabbit ears and how people sweat has helped two teams of Bucknell University engineering students reach the final round of an international biomimicry student design challenge.

The eight students — five biomedical engineering majors and three chemical engineering majors — competed against teams from all over the world, according to Donna Ebenstein, assistant professor of biomedical engineering.

"The student competitors — 50 teams from 10 countries — ranged from undergraduates to doctoral students. Two student teams from my Biomimetic Materials course were among the 12 semifinalists from seven countries," said Ebenstein. This is the first time the Biomimicry Institute has offered an unrestricted student challenge that was open to any school anywhere in the world. [Editor's note: The winning teams, announced Feb. 27, represented Iran, Latvia, Sweden and Norway.]

Biomimicry is the process of learning things from nature to enable humans to design better materials, to learn from nature and apply it to engineering design.

The first project, "The BioFaçade: Keeping Buildings Cool," is intended to reduce the amount of energy needed to keep buildings cool in part by harnessing solar energy. Its structure and function are inspired by evaporative cooling mechanisms found in plants and animals (transpiration and perspiration) as well as boundary layer effects observed in desert plants and solar tracking mechanisms used by sunflowers.

The façade reuses wastewater from the building and rain to facilitate the evaporative cooling mechanisms. It is constructed from two types of panels — solar panels and 'waterfall' panels — which can be positioned to create an effective boundary layer between the building and the outside environment.

The biofaçade team included senior biomedical engineering majors Neil Dold and Abraham Khan as well as senior chemical engineering majors Julie Kohn and Chrissy Kaufmann.

"We designed our project after learning more about natural mechanisms of cooling," Kohn explained. "For example, termites use the architecture of their mounds to circulate air, allowing for minimal temperature variation throughout the day. We were hoping to do the same."

Dold said, "The Biomimicry Institute wanted students to explore new ways to increase energy efficiency, optimize energy storage and/or decrease energy consumption. After learning that HVAC systems account for about 50 percent of residential energy consumption in the United States, my team chose to investigate thermoregulatory mechanisms employed by natural organisms to keep cool. We drew inspiration primarily from plant leaves and sweaty people."

The second project, "Thermoregulation in Forced Air Heating Systems," identifies an energy-related weakness on Bucknell's campus, specifically the misuse of heating systems in residence halls. In some buildings, heat runs even if windows are open, which causes heat loss to the environment and is a problem in the winter. Additionally, heat loss through pipe walls is a secondary problem with heating systems.

"As a Resident Assistant, I conduct room checks during breaks and the number one thing we are told to check for is to make sure windows are closed and locked," said biomedical engineering senior Anna MacAlister. "The energy wasted when windows are left open in individual rooms while the heat is on is substantial, and it doesn't just happen over breaks. We asked around campus and quickly determined that heat, and therefore energy, loss in residence halls is a big problem and it was time for a new solution."

MacAlister's team members included fellow biomedical engineering seniors Kelly Desharnais and Nicholas Barnett and junior chemical engineering major Brian Goldsmith.

Desharnais said, "The thermoregulation portion of our design was initially inspired by vasoconstriction mechanisms exhibited in jackrabbit ears and toucan beaks. To reduce heat loss to the environment, these animals minimize blood flow in their respective body regions when the surrounding temperatures are much colder than their body temperature. The sensor in the system was inspired by touch-sensing plants such as the venus fly trap and the pipe insulation was inspired by feathers and fur exhibited in several animals such as polar bears and penguins."

The system, which has the potential to reduce greenhouse gas emissions, would trigger pipe constriction and restrict heat flow to rooms when windows are left open, and insulate pipes to prevent heat loss to the building. It could also be used to retro-fit old buildings, meaning implementation will not be as costly as building an entirely new structure.

MacAlister said, "We knew we were going to be up against some substantial competition so we tried to focus on thoroughly addressing the specific challenge by creating an affordable, practical solution to an energy challenge on Bucknell's campus."

The Biomimicry Institute was founded in 2005 by science writer and consultant Janine Benyus, in response to overwhelming interest in the subject following the publication of her book, Biomimicry: Innovation Inspired by Nature. The Institute is a not-for-profit organization that promotes the study and imitation of nature's remarkably efficient designs, bringing together scientists, engineers, architects and innovators who can use those models to create sustainable technologies.

Contact: Division of Communications