By Heather Riley Chadwick, College of Architecture and Urban Studies
Last fall, a group of students and faculty members from the College of Architecture and Urban Studies and the College of Engineering traveled en masse from the Virginia Tech campus in Southwest Virginia to the National Mall in Washington, D.C., with a curious and sophisticated structure in tow. The Virginia Tech Solar Decathlon team was delivering two years’ worth of creative and physical work to be displayed and judged in a high-profile international competition sponsored by the U.S. Department of Energy.
Shortly after midnight on September 29, 2005, the team pulled onto the Mall with the walls of their innovative solar house glowing. “We wanted to intimidate the competition,” says Joe Wheeler, associate professor of architecture and one of the team advisers. The 18 teams, which hailed from as far away as Puerto Rico, Canada, and Spain, were competing to see who could design, build, and operate the most attractive, effective, and energy-efficient solar-powered house. Together, the solar houses created a forward-looking solar village.
The Virginia Tech team was off to an illustrious start. The transport of the solar house to the Mall had gone smoothly, thanks to the unique use of a lowboy chassis as the floor and foundation of the solar house. “This was a brand-new concept,” says Wheeler.
The floor/chassis receives a detachable gooseneck and rear axles. A truss on each side of the 48-foot span folds up around the 580-square-foot house to stiffen the structure and minimize deflection in the chassis while in transit. Then it unfolds and, with cedar planks laid within its structure, forms a wraparound deck. “We feel that in a manufactured housing context [this type of construction] could be economically viable,” Robert Schubert, associate dean in architecture and urban studies, told the Blue Ridge Business Journal.
Integrated with the architectural plan is an aquatic landscape design created by the Department of Landscape Architecture under the direction of Professor Ben Johnson. With seven inches of rain during the competition, the team was able to demonstrate the fully functional water filtering system that provides the house’s grey water from rainwater harvested from the roof. Although these features were not a part of the competition, the team overlooked no opportunity to be inventive or fine-tune an existing technology.
Research on the 2005 solar house began with lessons learned from the 2002 solar house. “The driving concept for the house centered on the integration of technology and aesthetics. Every technical decision was measured against its contribution to spatial effect. Each component was designed for optimum technical performance and rich expressive capacity,” says Robert Dunay, T.A. Carter Professor of Architecture and one of the faculty advisers for the project.
To promote interest and awareness across a wide range of students, an internal competition for proposals was held. Of the 50 teams comprised of architecture, industrial and interior design, and mechanical and electrical engineering students, seven teams were selected to advance their designs.
Eighty students in a special research class examined all aspects of the project and collaborated on such issues as material selection, energy collection systems, conservation strategies, and transportation. As part of this effort, students, in working with architects and engineers, surveyed manufacturers and suppliers to procure materials that were sustainable, energy-conscious, and a qualitative improvement for the residential environment.
Two of the house’s special features – transportation and those breathtaking walls – began with the 2002 house. One was a heavy-duty correction and one was an inspired evolution.
“At first, the students proposed moving the house in five pieces. But we had learned in 2002 that assembly on the Mall would not work,” says Wheeler. “All the systems have to connect. It took the full five days in 2002.” So a major research focus was how to get to the Mall in one piece.
A second critical design consideration that impacted transport was height. “We looked at a lowboy – a truck chassis that rides just six inches off the ground – because it would allow us to have a taller house,” says Wheeler. “We had a 12-foot ceiling and didn’t have to worry about bridges and overpasses. We only had to go around two between Blacksburg and Washington, D.C.”
The lowboy can be raised and lowered with airbags in back and hydraulics in front, as required. The truck was able to travel the interstate at the speed limit.
The chassis, which is the actual floor of the house, was the only part of the house built by professionals, who did the welding. Structural engineering students Joe McPherson and Ben Mohr worked on the structural calculations for the chassis and truss systems. After graduating in mechanical engineering, Mohr entered the graduate program in architecture.
“The student labor became skilled as we went along,” says Dunay.
All the engineering, architecture, industrial design, and interior design students worked together. “We taught architecture to the engineers,” Wheeler says. When an electrical engineering student guided the judges through the structure and explained its features, one of the judges commented, “You are obviously an architecture student.”
Before traveling to D.C., the students set the house up in a local Lowe’s parking lot to test the systems and construct the wrap-around deck. “It also provided ready access to a hardware store,” says Wheeler.
Thanks to that preparation, it took the team less than 12 hours to set up on the National Mall.
It’s a window – it’s a wall
But the house’s most dramatic feature – the reason it is bound to look familiar to millions of people – is its dramatic walls.
Three of the solar house’s walls are made of two layers of polycarbonate panels filled with Nanogel, an aerogel, translucent insulation. These walls suppress sound and transmit beautifully diffused light while delivering an extremely high insulation value. Inside the house, there is no need for electric lights from sunrise to sunset. The panels are lightweight, easily assembled, and could be manufactured separately for many applications. Between the polycarbonate panels are three systems: a motorized shade that allows the user to control light and heat; linear, actuated vents at the top and bottom that provide ventilation for further thermal control; and dimmer-controlled LED lights that allow the user to make the wall any color, no paint required. Subdued settings of the LED lights are idea for reading or watching television at night, while a strobe feature can get a party started.
The 2002 house had translucent walls. The research class for the 2005 house formed a team to enhance that feature. The result was a breakthrough in the window and wall concept that caught the attention of the ABC Extreme Makeover crew and was incorporated into a project seen by millions of people when the makeover of Carol Crawford Smith’s home was unveiled on February 12. The Smith house, designed by Dunay and Wheeler, uses several features of the solar house in a detached meditation room. “University engagement and the spirit of Virginia Tech are revealed as the technology of the meditation room offers the promise of innovation,” says Dunay.
The massive north wall of the Solar Decathlon house is a thick linear core made of structural insulated panels that house the batteries, electrical apparatus, mechanical equipment, and service functions, such as the kitchen, laundry, storage, and closets. The 20 lead-acid batteries can power the house and a small electric car for close to four days.
While the house operated off the electric grid for the competition, it is also designed to operate on the grid and can even be a power provider, says Mike Ellis, associate professor of mechanical engineering and one of the team advisers. “It’s possible for the utility company to owe the homeowner money,” he says.
The furnishings, including a sofa, chairs, coffee table, end tables, dining table, and a bed with six storage units beneath its sleeping surface, were designed and made by industrial design students. The laminate floor is made of sustainable harvested Lyptus wood from Weyerhauser. The team chose efficient appliances, such as an Energy Star-rated dishwasher and combination washer/dryer, as well as low-flow faucets for the house. In the elegant, slate-lined bathroom, a laminar flow of water cascades from a mirror onto a futuristic sink design, and the toilet offers a choice of two water levels for each flush. There is hideaway storage throughout the house, with pantry, closet, and medicine cabinet spaces that pull out from integrated cabinetry.
It’s a wing – it’s a roof
Above it all is a V-shaped roof that inclines toward the sun and appears to float. A row of transom windows encircles the house just under the roof, allowing natural light to pour in and reflect off the high, stretched-fabric ceiling. On one side of the house, the ceiling extends to 13 feet and at the other side it reaches 11 feet.
The roof is made of a lightweight, folded-plate wooden structure filled with foam insulation, with 36 200-watt SunPower photovoltaic (PV) panels on top. The solar panels are integrated into the roof form and can be adjusted for optimum energy collection.
The entire south-facing roof was available for collecting PV power because, unlike many designs, the Virginia Tech house did not use solar thermal collectors for water heating. Instead, power from the PV panels was used to operate a water-to-water heat pump (WWHP) that provides domestic hot water and water for a radiant floor heating system. The heating and air conditioning systems were designed to be coupled to the earth through the use of heat transfer pipes buried underground. “Of course, they wouldn’t let us excavate the Mall to install the earth-coupled system,” says Ellis. “So that part of the system was simulated using a traditional heat pump during the competition. Since the fall weather is not extreme, it was not a problem.”
Integrating the space heating and water heating systems so that they use a single WWHP reduced the cost and complexity. In addition, the water heating system was integrated with the air conditioning, so that thermal energy rejected from the air conditioning system can be used to heat water. “This recovered heat is predicted to supply 30 percent of the hot water requirement during the air conditioning season, freeing PV power for other applications,” according to the team’s report.
However, a persistent lack of sunshine during the competition eventually caused problems for the Virginia Tech team. The entire week had the equivalent of only 5.5 sun-hours. Instead of using batteries pre-charged before the competition to power their house, as other teams chose to do, the Virginia Tech team anticipated at least one sunny day, which would have provided the house ample solar power to run for the entire competition. Schubert said, “We’re proud of the team’s decision to operate the Virginia Tech house on solar energy. We were true to the spirit of the competition.”
The teams that ran their houses off pre-charged batteries had fewer complications in demonstrating their houses’ functions as the competition wore on. “It was a battery competition,” says Wheeler. “And we had fewer batteries.”
In spite of the dull weather, the Virginia Tech team began the competition in the lead, winning Best Architecture, Best Dwelling, and Best Daylighting, and tying for Best Electric Lighting. To win the Best Architecture prize, the team had to produce a delightful, functional home that incorporates the newest energy technologies. To win the Best Dwelling prize, they had to produce a buildable, livable home. The spaces had to be designed for regular household tasks, such as doing laundry and working from home, and be both easy for other builders to reproduce and attractive to homebuyers. To win Best Electric Lighting, the team had to supply ample interior lighting with as little energy as possible. For Best Daylighting, the team needed to effectively use natural daylight to illuminate the home’s interiors and reduce energy consumption. As with other contests, the team had to reproduce many elements of real world living. For example, they needed to create sufficient levels of light in the kitchen and home office work areas, and exterior lighting that would illuminate the house numbers and doors all night for safety.
On October 14, the competition concluded with the Virginia Tech team placing fourth overall. In its wrapup of the Solar Decathlon, the Washington Post reported, “The most dramatic entry was Virginia Tech’s.” By the time the teams left the Mall on October 19, their houses had been visited by tens of thousands of people, including Secretary of Energy Sam Bodman and a congressional contingent. Bodman visited the site on three occasions – at the opening and closing ceremonies, and once by himself to do his own surveillance.
In November, Schubert, Wheeler, and Dunay testified before the energy subcommittee of the U.S. House Committee on Science about “Winning Teams and Innovative Technologies from the 2005 Solar Decathlon.” According to Schubert’s testimony:
“We approach a watershed. Our lifetime has experienced an increased dependence on technology. Almost every amenity we enjoy is dependent upon centralized systems whose working and control are far removed from localized areas. A short curtailment of services sends neighborhoods and regions into temporary states of chaos. In the recent case of hurricane damage, available supplies of gasoline could not be accessed due to lack of electrical service. Whether from natural disaster or terrorist threat, large-scale technologies have exposed growing risks. We must reduce the risk of widespread technological failure by providing alternative distributed power solutions and backing up centralized systems with grassroots capability of generating power. With continued support and research of solar energy, this vision is achievable for the next generation.”
To meet the team members and the more than 100 sponsors, see more photographs, and learn more about Virginia Tech’s entry, visit http://vtsolar.arch.vt.edu/.
The primary sponsor for the Solar Decathlon was the Department of Energy’s National Renewable Energy Laboratory within the Office of Energy Efficiency and Renewable Energy. The Department of Energy’s private-sector sponsors included the American Institute of Architects, the National Association of Home Builders, BP Solar, the DIY (Do-It-Yourself) Network, and Sprint Nextel.