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September 28, 2011 / availableworld

Solar Decathlon Students Race to Renew Home Energy

A Purdue team member shows the biowall of the Solar Decathlon home.

Purdue University

Photograph courtesy Purdue University

Here’s one sure way to make a home greener: Install a wall made entirely of plants. But the Purdue University team members were aiming to add more than color to their Solar Decathlon home with their “biowall.” The vertical plant fixture acts as a natural filtration system.

(Related: “Shining Light on the Cost of Solar”)

By placing the biowall at the entry point for the HVAC air filtration system, the Purdue students were able to draw the air through the plants-filtering harmful chemicals from the air naturally. The wall is watered by rainwater collected from the roof and directed into the home.

Purdue’s entry is named “INHome,” short for “Indiana Home” and is designed as a practical, comfortable Midwestern dwelling. Many of the Solar Decathlon homes will go on exhibition or tour after the contest, but the plan is for the INhome to be placed in a neighborhood in Lafayette, Indiana, as part of a broader revitalization effort.

Tennessee students assemble their Solar Decathlon home.

University of Tennessee

Photograph courtesy Lauren Rogers

Putting solar panels on the roof is only one of the ways students are capturing energy from the forces of nature at the 2011 Solar Decathlon.

The U.S. Department of Energy (DOE) contest, which this year brings together 20 teams of college students-including competitors from China, Belgium, New Zealand, and Canada-challenges young people to demonstrate that renewable energy can be affordable, attractive, and practical.

(Related: “Quiz: What You Don’t Know About Solar Energy“)

After months spent perfecting their designs, the students descended on West Potomac Park on the National Mall in Washington, D.C., over the past two weeks to build their model homes. They will be on display and open to the public over the 10 days of the competition, during which the teams will be judged on factors such as architecture, comfort, and power self-sufficiency (known as “energy balance”). The teams have to show their homes can handle the energy demand of laundry, hot showers, and home entertainment.

(For videos of all of the teams, see special coverage by National Geographic partner Planet Forward, or take Planet Forward’s quiz to learn which house is right for you.)

The quest to capture energy from the sun inspired many of the teams to integrate other natural features into their designs, as is apparent in the Living Light home (above), the entry from the University of Tennessee‘s flagship Knoxville campus. The students are shown installing the two-section landscape around their home. One section is meant to be a natural habitat, and the other is for growing local crops. The plants are to be rotated seasonally, and to be fed by rainwater collected from the roof.

Tennessee’s students designed a home meant to echo the cantilever barns of southern Appalachia, incorporating the passive designs used by both by the native Cherokee people and early European settlers in Eastern Tennessee. The circulation of air through the building is meant to make the home as comfortable in Tennessee’s warm summers as it is in the cold mountain winters.

This year marks the fifth Solar Decathlon; the contest was inaugurated in 2002, and has run every two years since 2005. Team Germany won the overall competition in 2009.

A student works on a thermal storage system at the Solar Decathlon.

Ohio State University

Photograph courtesy Mark E. Walter

An Ohio State University student installs panels into one of the signature features of the team’s Solar Decathlon home-a “phase-change” material thermal storage system.

The Ohio State team’s heat storage system takes advantage of the energy transfer that occurs in material phase changes-just as when ice changes to liquid, it can cool a drink or the surrounding air. But the material that the students are using changes states at 86°F (30°C)-so it gives the system the ability to release air warmed to that temperature and pipe it through the house.

As a result, the students can store the heat of a warm day and release it during a cool night to keep the home comfortable. The Purdue system tracks U.S. National Weather Service data, and pre-charges the heat as needed. It can store up to 30 hours’ worth of warm air.

Ohio State’s team name is “Team enCORE,” a name meant to reflect a strong core at the center of the house, where the mechanical systems are located.

Appalachian State University students in front of their Solar Decathlon home.

Appalachian State University

Photograph courtesy Stefano Paltera, U.S. Department of Energy

Chelsea Royal, shown with other members of the Appalachian State University team, gives a briefing on their Solar Homestead. The students are gathered beneath the homestead’s Great Porch: an outdoor living space protected by an 8.2-kilowatt trellis of bifacial solar cells.

The team from Boone, North Carolina, modeled its entry after the frontier homes that dotted the Appalachian Mountains when the first pioneers arrived. Its home is the only one in the competition that has rooms separated into different buildings. The team sought to capture both the independence and ingenuity of the settlers in its design; for example, the adaptable, conditioned Flex Space, with an outdoor shower and kitchen, can serve as a home office, guest suite, or cabin retreat.

Like the Ohio State entry, the Appalachian State home uses phase-change material, a paraffin, to store heat during the day and release it at night.

 A rendering of Team China’s Solar Decathlon home.

Tongji University, Shanghai, China

Photograph courtesy Spencer J. Fisher, ACP/U.S. Department of Energy

The shipping container has become a symbol of today’s trade ties between East and West, but students from Tongji University in Shanghai have repurposed a half dozen of the huge crates to carry ideas instead of goods.

Team China has combined six recycled shipping containers into a Y-shaped solar house that is easy to transport, assemble, and expand. The “Y-Container” design creates separation between different areas of the house, as well as a large central communal area.

Another innovative feature is the house’s deck, which features a series of triangle-shaped containers that collect rainwater for reuse.

It is the second run at a Solar Decathlon for Tongji University. The school sent a team to Europe’s first Solar Decathlon, which was inspired by the American competition and took place in 2010 in Madrid. Tongji’s Madrid entry was a house made of native bamboo.

Solar Decathlon contestants cut cabinets for their house.


Photograph courtesy Stefano Paltera, U.S. Department of Energy

Cutting some cabinetry on the last day of home assembly, students from the combined Southern California Institute of Architecture and California Institute of Technology team prepare the finishing touches for an entry that looks like a spaceship on the outside. But the “CHIP” house (short for “Compact Hyper-Insulated Prototype”) is designed to be a comfortable, liveable prototype home on the inside.

The team sought to combine practical solutions with innovative design, producing the only home in the competition with insulation on the outside of the building’s frame. The exterior insulation is covered with a flexible vinyl wrap, which seals the home and gives it the distinctive futuristic look.

The home has two large openings that promote circulation: A low entrance that allows cool air to enter, and a high window that allows the warmer air to exit.

A rendering of Team New York’s Solar Decathlon 2011 home.

City College of New York

Photograph courtesy U.S. Department of Energy

The City College of New York team designed a home that sought to capitalize on one of the most untapped resources in Manhattan: empty rooftops.

Its Solar Roofpod is intended for the top of an existing mid-rise building, as a structure that would allow eco-conscious city dwellers to produce their own solar power, cultivate a rooftop garden, and retain and recycle storm water. It is also designed to distribute power to the rest of the building, and to provide a new urban green space for its residents.

The City College team, like other competitors, added a paraffin-based phase-change thermal storage system to their design. They also included solar thermal collectors that distribute the sun’s heat through a radiant floor system.

The “penthouse with a purpose,” as the team calls it, may return to the school’s campus in West Harlem for use as a visitor center and classroom. It also may be included in plans for a new school environmental science center on Pier 26 in Tribeca along the Hudson River.

The drying cupboard in Team New Zealand’s Solar Decathlon home.

Victoria University of Wellington, New Zealand

Photograph courtesy LEAP Australasia

Clothes dryers typically are one of the most energy-intensive appliances in a home; students from New Zealand’s Victoria University of Wellington sought to cut down on laundry power drain with a hidden drying cupboard. Solar-heated water is pumped through a heat exchanger, which in turns dries clothes or towels placed in the cupboard.

All teams in the Solar Decathlon have to demonstrate their ability to handle loads of laundry, and they are scored in the “Appliances” segment of the competition.

New Zealand’s team is named “First Light” because the island nation in the southwest Pacific Ocean is often heralded as the first place morning light shines at the start of a new day. As the first team from their country to participate in the Solar Decathlon, the Victoria University students based their home on the look of the traditional New Zealand holiday home, called the “Kiwi bach.” The home makes use of native resources, employing recycled sheep’s wool as insulation. All of the home’s furniture was designed by fellow students at Victoria University.

The view from the shower stall of Maryland’s Solar Decathlon home.

University of Maryland

Photograph courtesy Jeff Gipson, University of Maryland

The University of Maryland’s Solar Decathlon team sought to provide a living space so integrated with the surrounding world that a resident can take an outdoor shower, while still enjoying the privacy of a home.

The big shower window looks out on the landscape from a protected area within the structure, providing both the warmth of the sun and a view.

All of the Solar Decathlon teams are required to show that they can supply all the hot water needed for daily washing and bathing, and they earn points by successfully completing several daily 15-gallon (57-liter) “hot water draws,” meant to show they can provide the energy to deliver water at 110°F (43.3°C) in ten minutes or less.

The Maryland home, called “WaterShed”is inspired by the school’s native Chesapeake Bay ecosystem, and aims to show how water and energy challenges are connected. The students integrated systems to manage storm water, filter pollutants from greywater, and minimize water use. Also, the team sought to combat the brutal humidity that descends on the Mid-Atlantic region in the summer by incorporating an air-drying liquid desiccant wall.

(Related: “Pictures: In Search of Green Air Conditioning” and “Quiz: What You Don’t Know About Air Conditioning”)

The Maryland team was in the lead in early scoring in the competition, but the race was close, with updated results continually being posted throughout the 10-day contest. The Solar Decathlon continues through October 2.



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