Solar Decathlon Gives a Lesson on
the Value of Spray Foam

By: Claire Trageser
 

Photos courtesy of Homeway Homes and Team California

Two teams of American students shone at this year’s Solar Decathlon, a competition sponsored by the United States Department of Energy.
The contest, sponsored in part by the Spray Polyurethane Foam Alliance (SPFA), challenged students to spend two years designing, building, and running the most “attractive, effective, and energy-efficient solar-powered house,” according to the Department of Energy. Deputy Energy Secretary Daniel Poneman announced the awards on October 16 in a ceremony at the National Mall in Washington, D.C.

Students from the University of Illinois at Urbana-Champaign (UIUC) won second place with a score of 897.3 out of 1,000 possible points, while Santa Clara University and California College of the Arts students, or “Team California,” won third place with 863.089 points. Team Germany, the student team from Darmstadt, Germany, won first place for the second time in a row by scoring 11 points more than the UIUC team.

Both of the top American teams put spray polyurethane foam (SPF) to work in the structures of their energy-efficient homes.

NCFI Polyurethanes donated Insulstar spray foam for UIUC’s 800-square-foot “Gable House.” The UIUC team partnered with Illinois-based model home-manufacturer Homeway Homes to spray the two-component, closed-cell foam, which contains 20 percent renewable agricultural products. Homeway combined the Insulstar spray foam with Honeywell Enovate blowing agent to create the rebranded “Energy Strength Spray Foam Insulation System,” according to Ryan Abendroth, a senior architecture major at UIUC.

The team sprayed 8 inches (20.3 cm) of foam in the home’s walls, 9.25 inches (23.5 cm) in the open web joist floor, and 10 to 12 inches (25.4 to 30.5 cm) in the roof, Abendroth said. They sprayed from the outside in against an interior layer of oriented strand board (OSB). 

These innovations helped the team earn high marks in the contests where insulation mattered most.

UIUC’s team placed seventh in the Engineering Contest, which considered the home’s energy efficiency. They came in second, only 0.356 points behind the winning German team, in the Comfort Zone Contest, which required their home to maintain a temperature between 72° F (22.2°C) and 76°F (24.4°C) and a relative humidity between 40 percent and 55 percent. The team also placed second in the Net Metering Contest by producing four times the amount of energy than their house consumed.

Spray foam also helped Team California to win big in the insulation department. The team earned 100.239 out of 150 possible points in the Net Metering Contest and 63.088 out of 100 possible points in the Comfort Zone Contest. The team placed second in the Engineering Contest with 95 out of 100 possible points—only one point behind the winning team from Minnesota.

To achieve a superior level of insulation, Team California used Demilec (USA)’s SEALECTION Agribalance spray foam, which has more than 20 percent refined vegetable oils in the resin, on their 800-square-foot “Refract House.” California-based Spray Foam Energy Solutions sprayed the two-component, open-celled, semi-rigid polyurethane foam on the home’s walls, ceilings, and under the floor.

“It looks and feels like angel food cake and has great insulating properties,” said Mikell Warms, a junior civil engineering major at Santa Clara University who led the project’s windows and doors team and was part of the thermal team and the construction team.

Although students were not involved in the actual spraying, the organizational process of working with a spray foam contractor still provided an important lesson, Warms said.
“School safety protocol did not allow students anywhere close to the insulators, and we basically had to stop construction for two days while it was going on,” he said. “Given the time constraint we were on, this was a huge test in patience!”

On the first day of spraying, Team California also had a run-in with a building inspector.
“The city of Santa Clara building and electrical inspector happened to come again the day that the insulators showed up and hadn’t known about the spray foam we were using,” Warms said. “I had to run to the computer lab and print off every piece of technical information or documentation I could find concerning the product—thank goodness Demilec was well-organized in their website—and after they looked at the documentation, they decided it was OK to allow the insulators to begin.  They were worried about the electrical wires running through the walls and whether or not the insulation would harm them.”

Warms said the two-year project, which he started as a freshman, also taught him the importance of a home’s thermal envelope. He calculated the U- and R-values of the windows and insulation to determine whether the team could heat or cool the structure with the solar energy it was producing.

“At that point I thought the process I was forced to go through was fairly tedious, and I did not begin to understand until the competition just how important what I was doing was to the success of our project,” he said. “One of the large reasons why we didn't do even better than third place was because our windows and sliding doors allowed far too much air infiltration. When it started to rain and get cold, we didn’t have enough energy to power our thermal systems and still stay under net zero energy. No matter how effective our insulation was, it was as if we had no barriers to the external temperatures because of our doors and windows.”

Lessons like those are a big part of the reason for the competition, according to Solar Decathlon organizers and U.S. Energy Secretary Steven Chu.

“As part of the building competition, the next generation of green engineers, architects, designers, and professionals gain valuable experience that will help them to lead America toward a clean energy future,” Chu said. 

With the benefits of spray foam instilled in the students, SPF can now be a part of that future. And as the green building industry continues to grow through events like the Solar Decathlon, hopefully that future will be a little bit sunnier.

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