The Solar Decathlon Europe is not until 2014, but two European teams representing the Czech Republic and Austria are competing stateside this year.
Students at the Czech Technical University designed Air House, which doesn't target the typical young couples that constitute most first-time homebuyers, but rather a demographic familiar to the students: their parents, the 50+ empty nesters. The team cites data indicating that senior housing represents 20 percent of Czech households and that the number is growing. Conceptualized as a weekend country house, Air House can be transformed into a permanent residence when the owners retire.
Air House’s layout is straightforward: an independent L-shaped structure shrouded in a wood canopy and façade. The team calls it a “house within a house”, with the main living space located in the long leg of the L. Unlike many of the entries, the Czech team’s interior is a single loft-like space, with a sliding door that opens directly onto the outdoor living room. Built-ins on the south side are beautifully detailed in unfinished birch. The short leg houses the bathroom and equipment for the radiant chilled ceiling system, rooftop solar panels, and the graywater collection system (which serves the house’s constructed wetlands).
Team Austria designed the LISI house, a collaboration between students from Vienna University of Technology, St. Poelten University of Applied Sciences, Salzberg University of Applied Sciences, and the Austrian Institute of Technology. The house, not unlike SCI-Arc/Caltech’s DALE, surprisingly blurs the line between inside and outside. Large retractable sliding glass doors on the north and south sides disappear into the core areas, leaving the living area open to the elements--more like a covered courtyard than an interior. Lightweight curtains wrap the house for privacy and extra shade when low sun angles are at their most intense.
One student confessed that the glass doors, by the manufacturer Josko, were one of the most expensive parts of the construction. But considering how integral they are to the project, they seem worth it. They also point to two differences between the two European projects and some of the North American entries. First, the Czech and Austrian teams maximized single living areas and minimized auxiliary rooms, which streamlines passive heating and natural ventilation. (There’s a tiny, cave-like bedroom in LISI.) Second, heating, not cooling, is a larger pressing concern for energy use. Infographics produced by the Austria team indicate that heating demands for the house in Vienna are 9.7 kWh/m2 per year and cooling is 5.6 kWh/m2 per year. In Irvine, ostensibly a nicer climate year-round, the loads are actually higher due to cooling requirements: heating is 2.7 kWh/m2 per year and cooling is 10.6 kWh/m2 per year.
Or as Team Austria’s Philipp Klebert, a mechanical engineering student at Vienna UT, puts it: “In Austria, when we design passive houses for comfort, it is more about the heating. For most of us, this was our first time in Irvine and in the U.S. We had to get used to the weather.”