University of Nebraska-Lincoln architecture students and University of Nebraska-Omaha engineering students are collaborating to build a net-zero energy infill house of their design. The 2,000-square-foot Zero Net Energy Test House—ZNETH—is currently under construction in a neighborhood of existing 1,200-square-foot to 1,800-square-foot homes adjacent to the University of Nebraska-Omaha's South Campus. In addition to net-zero energy performance, the project is aiming for LEED certification at the Gold or Platinum level.
A partnership between the university's Peter Kiewit Institute, the Green Omaha Coalition, and the Nebraska Flatwater Chapter of the U.S. Green Building Council, the ZNETH project will serve as a test model for net-zero energy homes in Nebraska. The four-bedroom, three-bathroom house was designed by 100 students in the university's architecture and engineering programs in a process that began in 2007. The project is integrated into the curriculum of both programs, led by Avery Schwer, associate professor of construction systems in the university's College of Engineering, and Timothy Hemsath, AIA, NCARB, LEED AP, assistant professor in the College of Architecture.
To help achieve net-zero energy performance, the house is constructed of insulated concrete forms (ICFs) from Airlite Plastics' Fox Blocks, which offer roughly R-30 insulation (the company's vice president is a graduate of the university's architectural engineering program). It will be clad in a combination exterior insulation and finish system (EIFS) and a spray-on housewrap system called StoTherm NexT from Sto Corp. that will minimize air infiltration and create a stuccolike finish to complement other houses in the neighborhood. Energy Star appliances, as well as 60-watt-equivalent LED lights, will be installed.
The house will be powered through a combination of photovoltaics, four geothermal wells, and a vertical-axis wind turbine, and will be tied into the utility grid for net metering. Photovoltaic laminates atop the standing seam metal roof will comprise 1 kW of electrical capacity, and photovoltaic panels will generate another 1 kW. The geothermal system will provide heat for the home's water and in-floor radiant heat system.
"With just the solar and geothermal, we could achieve net-zero energy," Schwer says, "but the wind turbine will help." Still, he adds, the team won't know how effective the wind system will be until it's installed. The project will provide valuable data on the cost-effectiveness of residential wind power in the third-windiest state in the country.
The project's other sustainable features include a graywater system to recapture wastewater from bathroom sinks and the clothes washer for use by the house's toilets. Stormwater will be harvested for landscape irrigation. Bamboo flooring will be installed throughout the house, and kitchen and bathroom countertops made from a variety of recycled materials also will be used.
ZNETH is designed in the style of a Sears Craftsman kit house to fit into the neighborhood, which Schwer says the neighbors appreciate. "It's a design that people can relate to," he explains. "That was one of our initial goals: having an engaging project, one that people would look at and think, 'I could build a house like that.' For people to adapt to what we're doing, it has to be an engaging project."
In addition to the design, students are driving most of the material and system selections for the house. At the urging of a few students who thought the interior of the framed house would be dark, the team added a window. The addition of the wind turbine to the house's renewable portfolio was the result of another student's recommendation.
Three graduate students will occupy the house when it is compoleted. It will be their responsibility to monitor the daily performance of its renewable energy systems, which will be managed through an as-yet-unnamed energy monitoring control panel. The local utility will install two meters to monitor the house's energy use and energy production.
To ensure that the house provides a healthy indoor environment, the university's medical center will conduct indoor air quality monitoring tests throughout the students' occupancy.
Schwer says the project is planned to be complete in time for the fall 2009 semester, but delays could push the move-in date for students to the spring 2010 semester.