Students Push the Solar Envelope


While most of the students who were accepted to be part of the U.S. Department of Energy Solar Decathlon 2015 are putting finishing touches on energy-efficient homes, one team is using the competition as an unfortunate learning experience.

Florida/Singapore—a team that was comprised of the University of Florida, National University of Singapore and Santa Fe College—had to withdraw from the competition on Aug. 5.

The reason? Funding. And it’s not an uncommon concern among the 15 teams that remain.

“A couple of us have really been transformed into telemarketers the past few weeks,” said Kate McMillan, a senior architect student at Yale University, in an interview with the New Haven Register.

The “Y” House

This is Yale’s first year in the competition, which has been held biannually since the inaugural event in 2002. Yale’s house will run the team about $300,000 when they finish building the house to competition specifications.

As part of their project, they had the home constructed in three different areas of the country, according to the Register. All three will be shipped to Irvine, CA, where the decathlon will take place from Oct. 8-18.

The Yale house is just under 700 square feet, but it offers features many net-zero energy houses don’t have, according to the team’s website.

For one thing, it offers an open ventilation design with a central room that pressurizes and pushes air through. Vents in key areas allow hot air to escape, which in turn reduces the homes cooling load.

But the heart of the home—and the purpose of the decathlon—is the solar system the team chose, it said. For the “Y” house, team members went with a Photovoltaic Solar Thermal Hybrid System (PVT). The hybrid uses thermal collectors to transfer the heat from the solar panels and turn it into hot water.

Not only does transferring the heat make the panels themselves more efficient (hot panels have more resistance), it uses the heat for a source that conventionally would require electricity.

Keeping Competition, Local Needs in Mind

Yale isn’t the only team to take its first shot at this year’s decathlon. Of the more than 2,000 students to compete in this year’s competition, several are entering for the first time. A complete list of teams is available here on the Solar Decathlon’s website.

Each of the teams has the same basic requirements to compete. The teams must build houses that are:

  • Afforable, attractive, and easy to live in;
  • Comfortable and have healthy indoor environmental conditions;
  • Capable of supplying energy to household appliances for cooking, cleaning, and entertainment;
  • Able to provide adequate hot water; and
  • Capable of producing as much or more energy than it consumes.

Many of the teams have other objectives. Clemson University’s team is building a house that “embodies the history of South Carolina while looking to the future of sustainability.” Crowder/Drury built their house to be a core shelter in light of the 2011 tornados that devastated neighboring Joplin, MO.

And they aren’t the only ones who took natural disasters into consideration.

Weathering a Storm

The team at Stevens University thought beyond the energy efficiency requirement of their “Sure House.” According to the team’s website, its members wanted to build a house that will fit in a world with a changing climate.

“Hurricane Sandy devastated many houses on the Jersey Shore,” said Nariman Farvardin, the university’s president, in an emailed statement.

“This Stevens team said, ‘We will build a house that will satisfy all of the constraints the Department of Energy has given us, but there is one other thing that we want to do—we will also build a house that is hurricane proof.’”

With their third consecutive entry into the decathlon—previous teams took 13th place in 2011 and 4th place in 2013—the team collected waterproof details that would stand up not only against potential flood waters, but also against weight of debris.

U.S. Department of Energy / Solar Decathlon

Stevens University focused on climate and solar energy in its Sure House. The house can withstand a hurricane, with rigid insulation, storm shutters and composite sheeting, among other features.

On the energy side, Stevens’ Sure House uses a Daikin Skyair Heat Pump with Zoning Kit; a Zehnder Novus 300 ventilation system to recover heat that otherwise would be wasted; a PV (solar electric) hot water system; and LG Ultra Large Capacity Turbowash washing machine and hybrid dryer.

The team also chose super insulation with an R-value of 10, paid attention to details such as thermal bridging and used energy recovery ventilation (ERV) that has an efficiency rating of 92 percent.

For storm protection, the team turned to nontraditional envelope materials. The Sure House uses rigid insulation instead of fiberglass; places its electrical system above the BFE rather than below it; uses water-resistant cork flooring instead of wood or carpeting; has open web wood trusses rather than TGI or wood beams; and has composite sheathing instead of traditional wood sheathing.

Stevens also added storm shutters. When the sun is out, the shutters act as solar collectors and as a shading mechanism. But when it floods, they also keep the water and other debris from damaging the house and its envelope.

The house even features a resilient power system. In the case of a hurricane, it can offer its own energy to help power houses around them, according to the team’s website.

Picking up the Pieces

Meanwhile, other teams who had hoped to showcase their homes during the decathlon will have to wait until another time. As with Florida/Singapore, Team Tennessee—comprised of Vanderbilt University and Middle Tennessee State University—withdrew from the competition in February.

Ralph Bruce, a Vanderbilt engineering professor who served as the team’s lead, said the team will continue to work with Habitat for Humanity to finish the house it started. Its “Harmony House” was designed to be sustainable and efficient for lower-income families.

“We are grateful for the opportunity to get this far in Solar Decathlon and look forward to finishing the project independently,” said Bruce.


Tagged categories: Building Envelope; Energy codes; Energy efficiency; North America; Solar; Solar Decathlon; Solar energy

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