What is the best design for a livable home powered entirely by the sun that can be transported anywhere in the world and assembled in just a few days? This is the design challenge of the Solar Decathlon, the brainchild of the U.S. Department of Energy (DOE).

Nine collegiate teams from throughout the U.S. and two from Europe competed in the 11-day international event held this year in Northeast Denver in October. The teams designed, built and operated full-sized, solar-powered houses to demonstrate state of the art energy-saving technologies across 10 criteria including innovation, market potential, and energy and water efficiency. In the end, “winners” were selected, but in a broader sense, everyone is a winner. Since the first Solar Decathlon was held in 2002, ideas generated by the students have begun entering the marketplace and the students themselves have brought their energy and expertise to the homebuilding industry. This article concludes with examples of innovations from this year’s Decathlon.

Global interest in the Decathlon has been so great that the next Solar Decathlon in the U.S. has been pushed back to 2020 to give space and time for Solar Decathlons to take place in Europe, China and Africa. A professor from Hungary went along with one of the jury teams to observe the Denver event in order to help organize Solar Decathlon Europe.

To see the photos with the article go to: Solar Decathalon page 1 and Solar Decathalon page 2

The Scope of the Solar Decathlon

The Solar Decathlon event is impressive along many dimensions, from the time invested by the student and other volunteers to the range of innovations in the homes.

Time: selected teams spend nearly two years from inception to demonstration of their concepts at the
actual competition.

Commitment: Often these undergraduate and graduate students take reduced academic loads to bring their ideas to life. Teams ranged in size from 20 to 100. Each team brought a core group to Denver and stayed with their house throughout the competition.

Finances: fundraising for the house projects ranged up to $4 million and was undertaken by the students themselves.

Scope: the structures were first built and tested at the home institutions, then broken down, packed and transported to Denver where they were then re-assembled in less than a week.

Ideas: this was the real magic of the event, with each house in the temporary “solar village” demonstrating a cornucopia of innovations, some ready for the marketplace, others still in development or just so far out there that the rest of us will just have to mull it over before deciding whether to become an early adopter.

Adapting to Mother Nature

Weather was a theme in this year’s competition, both in the planning of the houses and in transporting them. Homes were designed to address specific needs based on climate in different regions of the country. Students on the Alabama team remembered the April 2011 “Super Outbreak” of tornadoes and incorporated a safe room able to withstand winds of 250 miles per hour in their southern vernacular house. The University of California Davis team designed their house to maximize water conservation in a state suffering through drought and used “drought wood” (from trees that died due to the drought) for the furniture and wood finishes. The University of Las Vegas team, coming from a desert region, likewise focused on water efficiency with their system for greywater reuse and collection of rainwater and condensation. The St. Louis team, with adequate rainfall in their region, designed a house with vertical hydroponic planters watered by rain that could grow food all year-round.

Team Daytona Beach lost 10 days of crucial construction time when Hurricane Irma hit Florida. And the Netherlands team had to scramble when Hurricane Harvey delayed the shipment of their structure through the Port of Houston.

During the competition itself, Hurricane Maria’s devastation of Puerto Rico and the raging wildfires in northern California seemed to emphasize the importance of withstanding the greater weather extremes associated with climate change. And that’s not to mention the wild swings Colorado weather visited upon the Solar Village in early October. In a post-event press release, DOE referred to the heat, cold, wind, sun, rain, fog, snow and mud as the 11th contest. The Missouri team’s “Crete” house earned extra points when the thermal mass of their concrete structure radiated enough heat through a cold night to allow interior comfort without use of a heating system, said juror Bill Rectanus, vice president of operations with Thrive Home Builders.

Solar Decathlon Contests

The “student athletes” competed in 10 categories: architecture, market potential, engineering, communications, innovation, water conservation, health and comfort, appliances, home life and energy. Each category was worth a maximum of 100 points, for a potential competition total of 1,000 points. The four top-scoring teams were the Swiss Team (872 points), the University of Maryland (822), the UC Berkeley/University of Denver team (807) and Missouri University of Science and Technology (758).

Teams could earn points three ways:

• Task Completion—Teams complete tasks that simulate modern living. They perform household chores such as cooking and doing laundry. They host dinner parties and game nights for fellow competitors. And, they are required to log miles driving an electric vehicle charged by the house’s solar electric system.
• Monitored Performance—Team houses and appliances perform to specified criteria, such as maintaining indoor temperature and humidity within a tight range, ensuring refrigerators maintain appropriate temperatures, and carefully controlling the flow of electricity between the house and the utility.
• Jury Evaluation—Jurors who are experts in fields such as architecture, engineering, homebuilding, water use and reuse, and communications, award points for features that cannot be measured, such as aesthetics, design inspiration and innovation.

Juror Bill Rectanus, whose company Thrive Home Builders was one of the sponsors, said, “I’d do it again in the blink of an eye. The students were very impressive, really inspirational.”

Team Netherlands, with the house they named “Selficient,” won the People’s Choice award. Middle school students who visited the solar village selected Northwestern’s “Enable” house for the Students’ Super Awesome House Award.

The competition returns to Denver in three years. If you can’t wait that long to further explore the students’ ideas, the DOE website, http://solardecathlon.gov/, contains descriptions of each team’s submittal. DOE also issued a report in October detailing the design innovations presented at the seven prior decathlon competitions. It can be accessed at www.nrel.gov/publications (“Insights on Technology Innovation – A Review of the U.S. Department of Energy Solar Decathlon Competition Entries 2002-2015”).

For a list of Solar Decathalon winners, click here: Solar Decathlon Competition Winners