WASHINGTON — Maybe the Solar Decathlon scoring should have a multiplier that takes into account how much money was spent on a house.
U.S. Department of Energy Deputy Secretary Daniel Poneman announced the winners of the 2009 Department of Energy Solar Competition on the National Mall at the end of the contest in mid-October. Team Germany, the student team from Technische Universtät Darmstadt, won top honors by designing, building, and operating the most attractive and efficient solar-powered home. The University of Illinois at Urbana-Champaign took second place followed by Team California in third place.
The German's formula? A million bucks. Put photovoltaic panels on nearly every exterior surface. Heat pump. That's it.
Team Germany's winning “Cube House” design produced a surplus of power even during three days of rain. This is the team's second-straight Solar Decathlon victory, after winning the previous competition in 2007.
New to this year's competition, the Net Metering Contest was worth 150 points towards the final results and was the most heavily weighted contest. It challenged teams to generate surplus energy, above and beyond the power needed to run a house, which they fed into a power grid.
Team Germany earned 908.29 points out of a possible 1,000 to win the competition, followed by the University of Illinois at Urbana-Champaign with 897.30 points, and Team California with 863.08 points.
The PV-all-over strategy paid off for the Germans, beating some other homes that were technological wonders that didn't produce the same amount of energy.
The University of Illinois at Urbana-Champaign created a barn-like house designed to honor the school's setting on the prairie. It was dull-looking, but it worked. The house featured 40 PV panels, solar thermal panels and a custom HVAC system with an energy recovery ventilator. The house was also tight, with 0.6 air changes per hour.
In the Appliances Contest, the U of I team earned the most points based on keeping a refrigerator and freezer cold, washing and drying 10 loads of laundry during the contest week, and washing dishes in a dishwasher five times during the competition — all on electricity generated only from sunlight. The team scored 93.53 out of 100 possible points. The U of I team also earned the maximum 100 points in the Hot Water contest's “shower tests,” which aimed to deliver 15-gal. of hot water in 10 minutes or less.
Designed with a San Francisco Bay aesthetic, the Team California house was architecturally stunning. The house took first place in the Architecture contest and earned 98 points out of a possible 100.
The California house incorporated active and passive solar heating. The passive heating used the orientation of the windows along with automated window shades. A MultiAqua air-to-water heat pump provided heating and cooling through both a fan coil and radiant floors and ceilings, using Warmboard and Uponor tubing. The fan coil controlled humidity during radiant cooling cycles. Enthalpy controls activated an ERV. A North Road heat pump water heater fed into a Heat Transfer Products SuperStor tank. Grundfos pumps moved the water, and all of the brass and controls were by Uponor.
Perhaps the most complicated system was in the Ontario/British Columbia house. Horizontally mounted direct flow Viessmann evacuated tube collectors in two arrays fed into a 110-gal. Bradford White storage tank. Heat from that water was pumped into a second space-heating tank. The space-heating tank was augmented by a geothermal heat pump with an R-410a Copeland scroll compressor that can modulate down to 10% capacity. Because the teams couldn't drill wells in the National Mall, a shallow pond underneath the house took the place of a geothermal well. Domestic hot water was supplied by yet a third Bradford White tank heated by a desuperheater off the heat pump, with electric resistance backup. The Ontario/B.C. house also had a dedicated cooling-only variable capacity heat pump that distributed cool air via fan coils. PV panels on the house provide 11,000 kW/year.
The University of Minnesota won the Engineering contest, which was evaluated by a group of engineers, who determined which solar home best exemplified excellence in energy systems design, energy-efficiency savings, creative innovations in design, and reliability of energy systems.