January 18, 2013
Stanford students build solar home in national competition
In a competition that could help transform the homebuilding industry, a team of Stanford students is redesigning the common house by putting utilities in a common core.
By Glen Martin
Computer-generated rendering of Stanford Solar Decathlon team's planned solar home. (Photo: Derek Ouyang / Stanford University)
A team of Stanford engineering students is constructing a solar house that could ultimately serve as a model for the sustainable home building industry. The dwelling, dubbed Start.Home, is based on a revolutionary design that integrates most of the infrastructure required for a home in a centralized utility unit. It will be unveiled at a solar home competition next fall in Southern California.
The Solar Decathlon pits top university teams against each other in the creation of game-changing solar houses – structures that could redefine the way solar energy is embedded into daily living. Derek Ouyang, Stanford's Solar Decathlon project manager, said he is happy with his group's progress, but acknowledges there have been some unexpected challenges.
"A lot of engineering majors at Stanford have never built anything," said Ouyang, who is pursuing a degree in civil engineering and architectural design. "We've discovered construction is really difficult – even if we're building from our own designs."
That was made abundantly clear to team members during a recent construction session supervised by engineering Professors Martin Fischer and Jonathan Edelman. The goal: Fabricate a prototype of the team's "Start.Core," a component that serves as a kind of solar home motherboard.
"We were working with [Fischer's] Managing Fabrication and Construction class," said Ouyang. "We split into groups that prefabricated different sub-assemblies of the core. It was a revelation – we found that just lining up conduit holes on the different sections can be a challenge. But in the end, we built two beautiful prototypes that will really help us move from the design to the construction phases of the home."
Stakes are high
A lot is at stake here, both for the Stanford students and – quite literally – the world. Sponsored by the U.S. Department of Energy and held biennially since 2002, the Solar Decathlon is considered a de facto "skunk works" for the development of practical solar technology.
So far, 112 teams and 17,000 students have participated in the Decathlon, and the event has been expanded to three global competitions, convened respectively in Europe, China and the United States. The 2013 competition will feature custom solar homes from 20 collegiate teams from four countries. It will be held October 3-13 at Orange County Great Park in Irvine, Calif.
As noted, the Start.Core is central to Stanford's design: a compact module that contains the home's primary mechanical, electrical, networking and plumbing systems.
"Basically, Start.Core is a 12-by-15-by-10-foot box. The bathroom is on one side, the kitchen appliances are on another, and you have easy access to the mechanical components – the hot water heater and electrical panels," said Emma Sagan, the team's business director and a student in the sustainable manufacturing, engineering and design program.
Most important, the design allows for the rapid scaling of solar home construction. "The cores will fit on any standard truck trailer so they can be hauled anywhere in the country and shipped anywhere in the world," she said.
At the same time, the Start.Core allows for the easy customization of individual homes. "One of the problems with sustainable residential developments is that the home designs are usually extremely limited," Sagan said. "The homes tend to look like they were punched out by a cookie cutter. But Start.Core allows you to approach a house more like a car. You have a standard central unit that services the house, but you customize around that – you define the living space the way you want."
A key concern of the team is the applicability of their designs to the real world. A solar house that can't be duplicated in a cost-effective fashion using existing industrial processes may be an interesting engineering exercise, Ouyang said, but it hardly meets the criteria of the Decathlon's judges.
You don't need an engineering degree to conclude that the extravagant use of photovoltaic panels might be the most expeditious route to an energy-efficient solar home, an approach that Ouyang says has been tried in past competitions.
Affordability is key
"One home had about $1 million in panels hanging from it," he said. "But that kind of obviates the whole point of the competition – designing energy efficient, aesthetically pleasing, affordable homes for today's market."
The current contest puts the target figure for raw materials and labor for each home at $250,000. Teams that spend more lose points.
Team Stanford's Start.Home will incorporate a 7-kilowatt photovoltaic system, which will be sufficient to provide an average of 30 kilowatt-hours of energy daily.
"That means you'd be fine even on cloudy days," Sagan said.
But the Stanford house isn't relying solely on photovoltaic panels for energy savings. It first uses passive systems – natural ventilation and natural daylight through high north-side windows that minimize high temperatures due to direct sunlight.
"Conserving energy – reducing the need for energy – is actually a bigger part of our strategy than producing energy," said Sagan.
Nor will Stanford's design incorporate any storage systems – that is, batteries. Instead, the home should be viewed as a microgrid component: It would feed excess energy into the established, centralized electrical grid. Such contributions would be credited to the household, and the home would draw power on those days – rare, it's hoped – when extra juice is needed.
The judges will monitor the performance of the house throughout the competition. That includes evaluating its livability. To demonstrate this quality, the team must perform common household functions in the home during the Decathlon.
In addition to a movie night, the team is required to host a dinner party in the house for rival teams. "We'll be having a cook-off to identify our best chef. Although I don't anticipate any difficulties, it will be a tense – but fun – meal," Sagan said.
Engineering and construction aren't the only challenging aspects of the competition. Building any home takes money, and designing and constructing a solar home for a national competition takes a lot of money – about $1 million. That doesn't involve just materials and construction costs, of course. Ancillary expenses such as travel, feeding and housing the Decathlon team while they're in Irvine, promotion and media contact, and alumni outreach also figure into the ledger. The Department of Energy provides $100,000 in seed funding, but after that the teams are on their own.
Sagan has been tasked with organizing the solar team's business squad, and much of her time is spent recruiting students to help draft and execute an effective fundraising plan.
"I'm finding that getting engineers excited about business is easier than getting business and humanities majors excited about engineering," she said, laughing. "Still, I enjoy working on the problem, and we're making headway. The university has committed $100,000, and we anticipate people will step up as our deadlines get closer."
Stanford students and faculty will get a chance to view the 1,000-square-foot home before it heads south to Orange County; it will grace the lawn next to Terman Fountain from March through September. Post-competition, the house will return to Stanford.
Back on campus, the home could be installed as a new ranger's residence at Stanford's Jasper Ridge Biological Preserve, or it could become a learning center for sustainable agriculture at a proposed School of Earth Sciences facility at the end of Santa Teresa Street.
Glen Martin is a freelance writer for the Stanford School of Engineering.