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Dwelling in Sunlight The 2007 Solar Decathlon PDF Print E-mail
By Andy Mannle | Saturday, 18 August 2007

This October, the 3rd Solar Decathlon will take place on the Washington Mall. Teams from twenty universities have been selected to compete in a competition to build a livable house that can run appliances and computers, wash clothes and dishes, provide hot showers, and even power an electric car – all with solar power. Like an Olympic Decathlon, the teams are judged in ten categories over the course of a week that sees a whole solar village built on the mall, and thousands of visitors catching a glimpse of the latest developments in solar design.

The Categories

1. Architecture – The architecture category is worth the most points, and houses are judged for Firmness - the sturdiness of their building materials; Commodity - easy access, space and the efficiency with which they incorporate technologies; and Delight –use of suprising materials, or surprising use of normal materials.

2. Engineering – The houses are judged on the electrical, mechanical, and plumbing systems; and how well they’re able to control the environment and atmosphere.

3. Market Viability – Because a key goal of the contest is to spread awareness and reduce the cost of building-integrated photovoltaic (BIPV) systems, this contest assesses how accommodating and livable the houses can be without being too costly.

4. Communications – The students run websites from their home offices and give tours to visitors. They are judged on how well they can communicate the technical aspects of their home, as well as the vision, and process of their project.

5. Comfort Zone – The teams are challenged to keep their homes between 72-76 degrees with a comfortable humidity level for the whole week.

6. Appliances - To earn points, student teams must maintain certain temperature ranges in their refrigerators and freezers, wash and dry 12 towels for 2 days; cook and serve meals for 4 days; clean dishes using a dishwasher for 4 days; and operate a TV/video player for up to 6 hours and a computer for up to 8 hours for 5 days.

7. Hot Water – Home is where the shower is, and this contest gives points for delivering 15 gallons of hot water in 10 minutes or less. Teams are required to run 9 showers over the course of the contest.

8. Lighting - A key aspect of sustainable design is how well it fits in with the natural environment. Points are earned in this contest for homes that successfully integrate daylight and electrical lighting for ambience as well as specific tasks and locations.

9. Energy Balance – This contest requires teams to use only the electricity generated by their solar systems for the contests. Points are awarded by adding as much power to the house batteries as is used up.

10. Getting Around - Points are awarded here based on how may miles each team can drive their street-legal, commercially available electric vehicles using the extra power generated by their house.

The 2005 Contest

In 2005, the University of Colorado won by getting the most points, carefully watching the weather and driving their car on cloudy days to gain the most miles. Being the 2002 winners, they had a good sense of the competition, and also placed first in the Communication and Marketing contests. Second place Cornell took first in Hot Water by being the only team to complete all 9 shower tests, and Comfort Zone.

"It's nice to be number two, but we were less interested in the gamesmanship or the Web site -- which allowed Colorado to win -- than we were in building the house we wanted to build,” said Cornell team member Larissa Kaplan.

The contest is sponsored by the Department of Energy’s Office of Energy Efficiency and Renewable Energy. Speaking with the American Institute of Architects, DOE spokesman Tom Welch said, “Solar energy technologies are clean, renewable, and reduce pollutant emissions. The Solar Decathlon serves to push research and development of energy efficiency and energy production technologies and raise its awareness among the public and students.”

In 2005, contestants built small but elegant homes full of light and soft natural materials. Combined with the latest designs in insulated windows, integrated photovoltaics, and energy-saving appliances, these homes offered truly innovative solutions to the age-old search for a clean, well-lighted place. The contest is held every two years, to give teams time to develop and build their homes. And as with any contest that pushes the bounds of technology, we are likely to see some new innovations at the 2007 Solar Decathlon.

New Technology

Building Integrated Photo-Voltaic – Known as BIPV, the idea is to incorporate the power-producing photo-voltaics into the building materials directly, to avoid having a clunky arrays on the roof. The new materials can be integrated with glass and used as canopies, or windows, or even made to look like standard roofing shingles.

Solar Skin – This is a PV material that is transparent, flexible, and highly efficient. And it is also an example of a technology in flux. In 2002 Solar Skin was expensive, and not as efficient as it had become by 2005. For this year, the materials are bound to be more powerful, more adaptible – and less expensive.

Energy Recovery Ventilator – This technology, showcased by the Cornell team, is a custom designed system that is very effective at saving energy in a ventilation system. While good ventilation is necessary for healthy air quality, it takes a lot of energy to heat cold air in the winter, and cool and dehumidify hot summer air. The way it works is by using tiny silica-gel packets, like the kind used to keep cereal and packaged food fresh. These are fitted to the air intake where the gel soaks up heat and humidity. It is then wheeled around to the exhaust, acting as a natural calibration to keep your home in the comfort zone with less energy.

Evacuated Tubes – A ‘magic box’ to tap the sun’s energy? That’s what the Cinncinati team dubbed this system they developed. Unlike Photovoltaics which turn the sun’s rays into electricity, the Evacuated Tubes gather heat. Simply put, it is a system of tubes within tubes. The inner tubes contain water which gets hot in the sun. Through a heat-exchange system, the water is used to vaporize lithium bromide gas. The gas is cooled in another chamber and put under pressure. When released from pressure creates it creates cooling air for the house.

The Winners

This year’s Solar Decathlon in October is bound to feature more cutting edge designs, and the latest developments in harnessing the sun’s power. Teams from as far away as Madrid, Montreal, and Germany have made the contest truly international, while seventeen teams from across the country will be putting their ingenuity, aesthetics, and technical expertise toward developing affordable, sustainable homes for us all. Whoever takes the tropy this year, the true winners are the communities of tomorrow. Let the games begin!


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