By Hiroko Sato
BOSTON -- To most environmentally minded consumers, gleaming solar panels may seem like the hallmark of a "green" home.
In the case of the little solar-powered house slowly coming into shape in Boston's Marine Industrial Park, though, heavy lifters of the carbon footprints are barely visible on the outside.
Attached behind the photovoltaic panels, for example, are tubes that have water running through them, says Julianne Rhoads, a Ph.D. candidate at UMass Lowell's energy-engineering department. The water transfers heat from the electricity-making gadget to a hot-water tank while helping solar panels cool off and run more efficiently.
The trellises, on which the 28 solar panels sit, are angled to help block summer light but let winter sun come in at a lower angle to flood the house. The "super-insulated" exterior walls, which Rhoads and fellow engineering students helped design, help trap heat inside in winter and keep heat out in summer.
The walls that separate the dining and living rooms from the two bedrooms glide like sliding doors to allow the spaces to merge. In seconds, you will have doubled the space for a dinner party.
Welcome to 4D Home, an "ultra-efficient house" to be showcased in Washington in October as part of the U.S. Department of Energy Solar Decathlon 2011. Team Massachusetts, that designed the house, is comprised of about a dozen University of Massachusetts Lowell students, mostly studying solar-energy engineering, and another dozen students from Massachusetts College of Art and Design.
The biannual international collegial competition accepted 20 out of 45 entries made for the 2011 challenge, according to Walter Thomas, a Ph.D. candidate who is the UMass Lowell team leader for the 4D project. This gave Team Massachusetts a chance to not only compete against their talented counterparts from across the world, including the Belgian and Chinese teams, but also receive a $100,000 DOE grant toward the home construction. The team is now finishing up the modular home in Boston's Innovation District, which will then be moved to Washington National Mall's West Potomac Park for public display during the competition from Sept. 23 to Oct. 2.
Just like athletic decathlons, the challenge has 10 areas to compete in, ranging from architectural design to affordability to market appeal. The house with the highest score will take the grand prize. There are no cash prizes, but the honor that comes with it would have a lot of meaning for the students.
"I don't know any other projects that Ph.D. students can work on that gets such international attention," said Thomas, a 45-year-old retired Air Force pilot from Londonderry, N.H., who is looking to make a second career as an engineer in the green industry.
The name, 4D, reflects the house's flexible design that accommodates a family's space needs and seasonal temperature changes. The team believes that adds another dimension to the house. Space efficiency is important, given that the world population is projected to grow from 7 billion in 2010 to 9 billion in 2040, Rhoads said. In the U.S., a family of four now typically lives in a 2,200-square-foot home, compared to a 1,000-square-foot home in 1950.
"The average family lives in a home that is twice the size of the home their parents grew up in," Rhoads said during a 4D presentation she recently made for New York-based nonprofit Ted Conferences. "So we are dealing with expanding population with increasing standard of living."
Team Massachusetts' home measures 945 square feet and is designed for a family of three. Rhoads said many entries from the 2009 competition had 8,000 to 11,000 kilowatt solar systems for similarly sized homes, costing $1,000 per square foot to build. Because it's super airtight, the 4D House only required a 6,500 kilowatt solar array and smaller HVAC systems. The cost is $250 per square-foot to build the house.
The project shows how modular home pieces made in a controlled indoor environment can increase the air-tightness of a house compared to conventional onsite constructions, says Michael Higgins, a Cambridge engineer who volunteers for the 4D project. Prefabricated pieces also eliminate the needs of shipping insulation, drywall and nails separately to a construction site, he says.
The team hopes to find a buyer for the house in New England after the competition to help pay for the $500,000 project cost. Many of the funds raised came in the form of in-kind donations, including Epoch Homes in Pembroke, N.H., that is making the modular pieces.