by Kathleen Weflen
BioHaus translates as living house or home. One of the most energy-efficient buildings in the nation, the 5,000-square-foot BioHaus incorporates cutting-edge technology with common materials. Completed in 2006, the two-story center provides study and living space for 32 students and teachers at Concordia College Language Villages in a northern forest near Bemidji. BioHaus reflects the trend in current German and Scandinavian architecture to build passive houses that use natural resources efficiently.
Natural light and solar heat pour through a wall of south-facing windows. With passive solar design, super insulation, and a geothermal system, the house maintains a comfortable temperature of 70 degrees year-round. BioHaus uses 85 percent less energy than a house of the same size built to meet Minnesota standard energy code, thus drastically cutting carbon emissions. (It also surpasses the LEED certification standard of 60 percent less energy consumption than code.) BioHaus received the 2007 Minnesota Environmental Initiative Award for air quality and climate protection.
The structure uses German technology and received funding from the German Foundation for the Environment. The architectural design by Minneapolis-based Intep called for a frame of Minnesota timber. Local Bemidji contractors built BioHaus, securing about 85 percent of building materials locally.
Solar rays of heat enter through the windows as short ultraviolet waves, which strike objects, become longer, and move back into the air. (Long heat waves tend to remain indoors because they don't travel through glass as well as short waves do.) Luckily, outside air temperature has little influence on solar radiation, so bright sunlight generates heat even on frigid days in the north.
Inert gas sandwiched between triple panes of glass insulates the windows. Thick frames of wood and cork have a double seal. To prevent airflow, a locking mechanism engages the solid seal evenly around the frame.
Like shutters, outside blinds help protect windows from cold air, excessive heat, and stormy weather. Electronic controls inside allow the occupants to direct sunlight by opening and closing separate upper and lower shades.
Like a polar explorer bundled in layers of clothing topped with Gore-Tex, BioHaus has insulating layers entirely wrapped in an exterior jacket, zipped up tight. BioHaus achieves high R-values (resistance to heat flow) with double layers of insulation: spray foam and vacuum insulation panels made from aluminum bags vacuum-packed with silica dust. Minnesota code calls for insulation rated R-19. BioHaus has R-70 in walls above ground. Ceilings have 48 inches of insulation to achieve R-100.
A closed-loop geothermal system circulates a water-glycol mix through three 200-foot-deep wells. The fluid is warmed to 40 degrees by the relatively constant temperature below the earth's surface. A heat pump, which operates like an air conditioner in reverse, concentrates this heat from the ground. The concentrated heat is transferred to a holding tank of hot water, which supplies radiant floor heating as well as booster heat for the ventilation and solar hot-water systems.
The super airtight building requires a continuous supply of 100 percent fresh air (not recirculated). The ventilation system interacts with a 100-meter-long earth-tube system, nine feet below ground, which works as a ground-to-air heat exchanger bringing in fresh pretempered air.
Solar roof panels heat water for showers, sinks, and washing machines. Water tanks with plenty of insulation conserve energy collected by the solar and geothermal systems.
BioHaus hosts annual public tours. Young people from across the nation come to BioHaus to spend weeks at a time immersed in science and language learning. Students can see real-time energy information tracked on sensors indoors and out. Visit BioHaus online at www. concordialanguagevillages.org/newsite/languages/german/biohaus.php.