When students from Washington University in St. Louis embarked on creating an energy-efficient home for this year’s Solar Decathlon, they chose an unlikely building material: concrete. Aesthetic preferences didn’t drive their decision. Instead, they picked concrete—over materials like wood and metal—because of its ability to withstand tornados, hurricanes, and floods. “We chose it because of its resiliency, which is pertinent now more than ever,” said Adam Goldberg, a graduate architecture student at WashU.

Their dwelling, called CRETE House, is one of 11 prototypes created by collegiate teams for the 2017 Solar Decathlon, the biennial competition and expo organized by the U.S. Department of Energy that aims to prepare students for careers in renewable energy. Multidisciplinary teams from universities in America and abroad are invited to design and build solar-powered homes that range between 600 and 1,000 square feet.

The program was launched in 2002 by physicist Richard King, who wanted to cultivate awareness about solar energy in residential design. Over time, the design brief has expanded to include a range of sustainability issues.

In addition to the competition, the program aspires to help educate the public by showcasing the student-designed dwellings. Past expos have been held at the National Mall in Washington, D.C., and in a park in Irvine, California. This year, organizers moved the event to Denver, a fast-growing city that has demonstrated a commitment to transit-oriented development. The free expo, which opened Thursday and runs through October 15, is being held in an emerging suburb, on a vacant parcel adjacent to a new light-rail station. “This is a great place,” said Linda Silverman, director of this year’s Decathlon. “There’s a built-in interest in the Denver community for what we’re doing.”

The prototypes vary widely in terms of form, layouts, materials, and building systems. In addition to basic requirements related to energy production and efficiency, teams often take on additional design challenges. This year, several groups addressed the issue of aging in place, and many incorporated living walls and gardening systems. Students from Switzerland went beyond the traditional notion of a house and sought to engender a sense of community. Their dwelling—made of laminated veneer plywood—contains a sleeping nook, an open cooking and dining area, a bathroom, and a flexible space that can be used for co-working and socializing. “It’s meant to be a house for the whole neighborhood,” said Margaux Peltier, an architecture student at the Swiss Federal Institute of Technology in Lausanne.

For other teams, environmental threats were a guiding concern. In their Surviv(AL) House, Alabama students incorporated a steel-framed “safe room,” meant to serve as an alternative to an underground bunker. The concept was influenced by the rash of tornadoes that ravaged the state in 2011. “I know two classmates who lost their house in the outbreak,” said Scott Jones, a mechanical engineering student at the University of Alabama at Birmingham. For students at the University of California, Davis, the state’s extreme droughts inspired a dwelling focused on water conservation. Easy-to-read monitors keep track of water usage, and “drought wood”—lumber from trees killed by drought—was used for exterior cladding and interior accents.

The WashU team said its home, made of precast concrete, underwent a wind test, which involved shooting a two-by-four wooden board at the structure at 200 miles per hour. The board “was turned into splinters,” said Goldberg. He added that working on the Solar Decathlon project has been incredibly rewarding. “This is the best learning experience that any architecture, engineering, construction management, and even business student can have,” he said.

UPDATE:

Competition results were announced on October 14, and for the first time in the Decathlon’s history, cash prizes are being given to winners. Moreover, every team that completed a house will receive $100,000. The Swiss team won the $300,000 grand prize for its NeighborHub design, which the jury felt best demonstrated clean power production, energy and water efficiency, design excellence, and market potential. The University of Maryland took second place and will receive $225,000. Third place went to the joint team of University of California, Berkeley and University of Denver; they will share a $150,000 prize. In addition to overall winners, awards were given in 10 different categories (hence the name Decathlon). To see the full competition results, visit the Solar Decathlon website.

PROJECTS + TEAMS

CRETE House
Washington University in St. Louis

House by Northwestern, Enable
Northwestern University

NeighborHub
École Polytechnique Fédérale de Lausanne; School of Engineering and Architecture Fribourg; Geneva University of Art and Design; University of Fribourg

Our H2Ouse
University of California, Davis

reACT
University of Maryland

RISE
University of California, Berkeley; University of Denver

Selficient
HU University of Applied Science Utrecht, Netherlands

SILO
Missouri University of Science and Technology

Sinatra Living
University of Nevada, Las Vegas

Surviv(AL) House
University of Alabama at Birmingham; Calhoun Community College

The BEACH House
Embry-Riddle Aeronautical University; Daytona State College