A small row of unmanned houses in Tennessee is operating at optimal efficiency. Are these our energy-efficient future?
It has become a familiar sight: a tidy row of newly built—and empty—houses in an economically crippled American city. Consider it a sign of the times, the inevitable result of shortsightedness, poor planning, and bad politics. In the Wolf Creek neighborhood of Oak Ridge, Tennessee, the same scene is unfolding. There are four houses, immaculate and empty, sitting side by side. But instead of representing the worst of our excesses, these structures are beacons of saving and frugality.
Conceived of by a team of scientists at nearby Oak Ridge National Laboratory, the three-bedroom houses aren’t standing idle. Inside, at programmed times throughout the day, showers run, toilets flush, dishwashers wash, and lights turn on and off. Like the driverless Google cars zooming along California roadways, the Wolf Creek houses function autonomously; they are unpopulated labs in an intriguing experiment about energy efficiency that will be simulating the national average of energy consumption, day-in and day-out, for over two years.
The rationale behind the research is simple: 40 percent of the nation’s carbon footprint comes from its buildings. In order to reach President Obama’s ambitious goal of reducing emissions by more than 80 percent by 2050, finding cost-effective ways of tamping down home energy use is a must. For their part, the ORNL researchers are monitoring 250 channels of data being spewed out of each of these houses to figure out where consumers, homebuilders, materials manufacturers, and even appliance-makers can most affordably lower their impact.
“We have dozens of experiments in these houses,” explains Patrick Hughes, the director of ORNL’s building technologies research and integration center. “And we’re going at it with analytical horsepower in terms of using the data to physically validate very detailed models of the home, so that between the data and the models we can sort out where the bang for the buck is coming from.”
According to early data, the most extensive cost-cutting could come from relatively simple technological solutions like better building methods, more efficient washing machines, or next-generation heating pumps.\n
The Zero Energy Building Research Alliance (ZEBRAlliance), as the project is known, is a collaboration of ORNL, the local utility company, the Department of Energy, BarberMcMurry architects, and the Schaad Companies construction firm. In addition, a number of industry leaders—such as Whirlpool and the country’s largest water-source heat-pump manufacturer, ClimateMaster—are offering prototype products so that ORNL can assess their performance. According to Hughes, the houses the Alliance constructed are 55 to 60 percent more efficient than normal, code-built houses.
According to early data, the most extensive cost-cutting could come from relatively simple technological solutions like better building methods, more efficient washing machines, or next-generation heating pumps.
One of the more exciting technologies on trial is an advanced cellulose technology that incorporates a so-called microencapsulated phase-change material, which allows the insulation to physically change its properties in response to heat. When the sun beats down on the house’s exterior surface, talc-like capsules absorb the energy and, in turn, keep the temperature inside the house relatively constant. Normally, the temperature difference between the hot outdoors and the cool indoors would drive heat into the house, and electricity (for air-conditioning, say) would be required to keep the temperature down. In laboratory tests, the cellulose material appeared to reduce heat gain and loss through the walls while also delivering a 25- to 40-percent drop in costs. Over time, the ZEBRAlliance houses will show definitively if such performance can be sustained. Other notable technologies on trial include a new type of heat pump that handles a suite of functions: heating, cooling, water-heating, and dehumidifying. Another one of the houses will experiment with all-LED lighting.
Hughes says that companies are clamoring to test their products in these houses, because the simulations are scientifically rigorous. The private sector is looking for technologies that will work for the average homeowner while being economically viable to produce.
Schaad Companies, for instance, is riding out the down housing market by trying to improve its competitive advantage in a marketplace with little differentiation between builders. It is already reaping the benefits of its involvement. Before it even built a single one of the houses for the ZEBRAlliance project, the know-how it gleaned from the ORNL research team allowed it to build houses that were more than 30 percent more energy efficient than what they were building before.
A simple fix the ORNL scientists suggested: Move the heating-and-cooling unit, as well as its associated ductwork, out of the attic, which can get boiling hot during summer months. Schaad’s CEO, Jennifer Banner, recalls one of the ORNL team members telling her that keeping those units in the attic was “the same as taking your refrigerator, putting it in a 400-degree oven, opening the door of the refrigerator, and asking it to make your food cold.”
“We wanted to address energy-efficiency, which, for us, is what ‘green’ meant,” explains Banner. “I didn’t just want to use bamboo and call it ‘green.’” Schaad has also created a new business unit capable of retrofitting any of the 9 million existing homes served by the TVA power company.
An example of foresight and innovation at a time in desperate need of it, Schaad is hard at work to ready itself—and its research—so that it can greet a resurgent housing market, whenever that may happen, with the kind of smart, efficient building the country has long needed.
And until that time, the houses will hum along, producing data streams that may point the way forward.
Photos from the Department of Energy, Oak Ridge National Laboratory