Every two years, university teams from around the country and around the world converge on Washington, D.C., and transform the National Mall into a solar village of homes that showcase innovation in energy generation and efficiency, inspire the next generation of green architects and engineers, and spread the sustainability mission to an eager public.

The 2009 Solar Decathlon, which is open to the public Oct. 8–13 and Oct. 15–18, is the fourth iteration of the U.S. Department of Energy's (DOE) biennial competition in which students design, build, operate, and market a solar-powered house. Forty teams submitted proposals to the DOE, and the 20 chosen have spent the last two years putting their architecture and engineering training to real-world use, creating an inspiring array of prefab dwellings with a diversity of styles, floor plans, products, and technologies. The homes, each up to 800 square feet in size, are transported to Washington and rebuilt on the Mall in the week preceding the competition's opening. Each structure is self-sustaining, combining active solar collection through rooftop-mounted or building-integrated photovoltaics and solar thermal with passive solar design techniques, energy-efficient building envelopes and products, and high-performance construction. Water conservation, resource-efficient materials, and locally obtained materials are incorporated, and attention is paid to indoor air quality, occupant comfort and lifestyles, and feasibility.

Many of the homes draw inspiration from the region from which the students hail, both to ensure the houses are optimized for the climate (most of the dwellings will find a permanent spot on or near campus) and to showcase to the local community the attainability and practicality of such practices in their area. Most of this year's competitors also used proven technologies and materials to demonstrate that a super-efficient green house doesn't have to be built with whiz-bang products.

Over the course of the competition, each project is judged in five subjective categories—architecture, market viability, engineering, lighting design, and communications—and in five categories scored objectively through performance testing—comfort zone, hot water, appliances, home entertainment, and net metering.

In an effort to ensure—and showcase—the livability and comfort of the homes, the "home entertainment" portion of the competition requires the teams to host two dinner parties and a movie night, illuminate work areas and keep lights on during specified times, operate electronics, and undergo a cooking performance test.

For the first time, the solar village is connected to the local utility, Pepco, to monitor net metering. Teams will earn 100 points for achieving net-zero over the course of the event, plus additional points if surplus power is sold back to the utility.

For the students, the competition is an opportunity to put years of learning into practice, and the joint effort of architecture and engineering promotes collaboration across multiple academic disciplines that must learn to adapt to each other's different ways of thinking. "These are our energy leaders of tomorrow," says Richard King, director of the Solar Decathlon for the DOE. Indeed, the teams leave armed with an experience perfectly timed for the burgeoning green jobs movement.

But the education component goes far beyond the students themselves. The event's prominent public location, along with its emphasis on effective promotion and communication by each team, is key to demonstrating the potential for zero-energy homes to the public, which is exposed, often for the first time, to the possibilities of renewable energy, energy efficiency, and green building. What's more, King says the competition is a springboard for innovations and interpretations that professional builders and designers can incorporate into their own structures.

The DOE's Solar Decathlon was open for public tours Oct. 8–13 and Oct. 15–18. For more information on the competition and the teams, visit www.solardecathlon.org. The DOE also posted video previews on YouTube.

The Solar Decathlon frequently serves as a proving ground for cutting-edge technology, much of which is developed by the students themselves. Read about how student teams are taking some of their technological innovations to the mass market.

We've also rounded up the eight best new technologies being employed by Decathlon teams this year. Check out the video.

COMPETITION UPDATE:2009 solar decathlon winners announced!.

Navigate through the team list below for our coverage of each team's Solar Decathlon house.

Cornell University
Iowa State University
Penn State University
Rice University
Team Alberta
Team Boston
Team California
Team Germany
Team Missouri
Team Ontario/BC
Team Spain
The Ohio State University
The University of Arizona
Universidad de Puerto Rico
University of Illinois Urbana-Champaign
University of Kentucky
University of Louisiana at Lafayette
University of Minnesota
University of Wisconsin-Milwaukee
Virginia Tech