Approaching Zero

Approaching Zero

Nov 19 - Electric Perspectives

Imagine living in a home where the electricity meter sometimes runs backward, making you a net producer of electricity. That scenario is a reality in some of the Department of Energy's (DOE'S) nearzero-energy homes, a project run out of Oak Ridge National Laboratory's Buildings Technology Center. While low or no electric bills are an obvious benefit, highly energyefficient homes and businesses also reduce the amount of electricity that needs to be generated, thus reducing emissions, says Jeff Christian, the technology center's director. Tennes see, where several of the homes are built, ranked third behind California and Texas for smog, according to a September 2003 Environmental Protection Agency report.

In one of these houses, the daily electric cost was 82 cents, compared to $4-5 a day for a conventional home in the same area. The houses were built for approximately $100,000. Some of the technologies featured include airtight envelope construction, advanced structural insulated panel systems, insulated precast concrete walls, a heat-pump water heater, geothermal systems, grid- connected solar photovoltaic, and solar integrated raised metal seam roofs. The houses also provide high indoor air quality as well as mold, mildew, and moisture control. In fact, the advanced construction techniques make these houses six times as airtight as similar houses with 2-by-4 wood frame construction.

Jeff Christian, director of Oak Ridge National Laboratory's Buildings Technology Center, tries to achieve some balance.

"The effort must be all-inclusive, so we're not limiting our approach to space heating, cooling, water heating, lighting, and major appliances," says Christian. "We are integrating sensors so the homeowners can monitor their energy usage and savings."

DOE'S long-term goal is to develop technologies that enable net- zero-energy homes at low incremental costs, but that goal hasn't been reached yet. Today, the focus is on encouraging new homeowners and builders to consider houses that boast high efficiency and, in some cases, use solar panels to generate some of their own electricity.