By Michael Schaffer - Managing editor
Imagine living in a less than 600-square-foot, $350,000 "green living" solar-powered house that only uses the electricity it generates?
That's what naturalists Jacob Ahee and Hannah Wiltamuth have been doing in the Iowa State University-designed Interlock House since August at Honey Creek Resort State Park in northern Appanoose County at Rathbun Lake. The house is designed for two people.
Well, they don't actually live in the house, but they treat it like they do.
"We take showers here after kayaking or after hiking," Ahee said of the solar-powered demonstration house Saturday afternoon, Sept. 10. "We do prepare food in here. We do loads of dishes and laundry. We're supposed to treat it like we would a house that we lived in. But nobody has to stay in here overnight."
Now called the Activities Building, it produces its own electricity from solar panels fastened to the southern-facing roof. The electricity from the panels are stored in batteries for future use.
When house occupants tap into an outlet for electricity or use an appliance, it draws first from the electricity stored in the batteries. If conditions are not favorable for the solar panels to produce electricity, like a cloudy day, users might draw from the electrical grid.
Ahee said the house is designed to function independent of outside electrical sources and return to the grid more electricity than it uses.
"It's suppose to have a net zero consumption of electricity," Ahee said. "It is tied into the electrical grid. But it should produce more than it consumes every year. It should produce more input back onto the grid."
The solar panels do double-duty, Ahee said. Non-potable water circulates through the panels into pipes under the floor to produce heat during colder days.
"That's what we're hoping to keep us warm this winter," Ahee said.
Additional sources of heat during colder days are the southern-facing windows and four glass doors that open up to a specially designed area with a rock and stone floor capable of being closed off with a portable glass nano wall. Close off the area with the wall and the sun heats up the floor creating an oven effect where warm air rises up and into the living space through vents near the ceiling while vents near the floor allow cooler air to be pushed back into the enclosed space.
"In the winter, we've got this door. It's called the nano wall," Ahee said. "Basically it creates a mini green house in here."
But the furnace-less house has yet to operate during an Iowa winter. Something Ahee said should be an important benchmark.
"So actually (in the winter) it's going to be a kind of a trial by fire," Ahee said. "We're going to see. Hopefully it will work."
Devices mounted throughout the house monitor temperature changes and that information is sent to Iowa State and a firm in Colorado, Ahee said. Plus, a weather station attached to the house monitors the outside temperature.
On Sept. 10, 2011, several devices were plugged in and were using electricity. The inside air temperature was 73 degrees. No lights were on but the interior of the house was very bright.
Living green means more than not using any outside electricity. Many of the materials used in the construction of the house are recycled or environmentally-friendly.
Ahee said shredded blue jeans were used as insulation in the walls, farm-raised bamboo was used for the floors, farm-raised cedar was used for the siding outside and crushed glass and concrete were molded to make the counter tops.
Ahee said they plan to build a small wind turbine to supply electricity for the basement. At some point the basement, which was not part of the house's design, is where many naturalist activities will be held plus house a classroom.
The house has a modern kitchen with an oven, microwave, dishwasher and refrigerator/freezer. It has an appliance that both washes and dries clothes. It has a sleek-looking bathroom, a Murphy Bed in a room that is both bedroom and office with a desk, cabinets, shelves, central air conditioning and water heater.
The Interlock House was built in 2009 and participated in the Solar Decathlon in Washington, D.C. It was purchased by Cargill and donated to Honey Creek Resort State Park, Ahee said. Tour the house Wednesdays and Saturdays from 3:30-4 p.m.