August 10, 2007 4:00 AM PDT
Energy geeks compete for coolest solar home
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To power the Solar 7, the MIT crew is installing a 9-kilowatt solar array--much bigger than what houses of this size would typically need. The electricity will be stored in 24 batteries capable of holding 70 kilowatt-hours, which can run the home in the absence of sun and be recharged in two days.
The excess power is essential to the competition, as Solar Decathlon contestants are judged on how far they can drive their DOE-provided electric car.
The building will also be wired with sensors to measure the fluctuations in temperature, which is a way for judges to gauge the builders' ability to maintain a comfortable indoor climate. That information can also serve prospective owners looking to track their energy consumption, noted Fucetola.
But for all its high-tech components, good architectural design is perhaps the most challenging aspect of the project. That's in addition to making it a livable space with room for a bedroom, full bathroom, dining area and living room.
For starters, the house needs to be modular and assembled by nonprofessional builders because contestants need to transport and reassemble their creations on the National Mall. The initial design, which originally came out of a sustainable architectural workshop, needed to be substantially altered to make dismantling and reassembly easier, said Keville, adding that the entire house will be held together by screws, not nails.
Design choice can also substantially reduce the amount of energy required to run a home. For example, the house's roof will maximize the amount of daylight that comes in, thereby cutting down on electricity requirements. At the same time, the roof is angled so light doesn't pour in during the hottest part of the day.
Similarly, MIT Solar 7 will have a front awning and windows on the opposite side of the house to maximize air flow through the home, which provides clean air and helps cool it.
"One of the guiding principles is that we would be using daylighting and natural ventilation as much as possible," Fucetola said.
Also planned is a water-reclamation feature that will collect runoff water and store it for landscaping, and a roof that the designers hope will prevent ice buildup.
As the student lead on the project, Fucetola, who spends four days a week at the site, has become something of an evangelist, recruiting volunteers by asking interested passersby to get involved. "I tell people in elevators about this," he said.
The team hopes to sell off its creation as a way to fund MIT's entry in the next Solar Decathlon competition in two years. (Realtors have expressed interest.)
So will MIT Solar 7 live up to its billing and be a "net zero energy" solar home? Keville says the home will generate more electricity than it consumes for most of the year.
"We know for nine months of the year that we'll be net energy positive," he said. "We may be break-even in January and February. We'll find out when we bring it back to Cambridge."
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