Most of the time, even resident Kim Charles does not notice the solar panels on her roof, the whisper of her SEER 17 heat pump water heater, the airtight, moisture-managed construction of structural insulated panels, the integrated design that allows most of the home's plumbing to reside within one wall, saving precious energy.

What Charles does notice is a power bill that amounts to less than a daily cup of coffee. Thanks to a 15 cent-per-kilowatt-hour credit paid by the Tennessee Valley Authority for electricity piped back to the power grid, her meter literally runs backwards on sunny days. In 2006, she paid an average of 41 cents per day for electricity.

Charles's home is among five in this Habitat for Humanity community located in Lenoir City, Tenn., and outfitted with the latest in energy-saving technologies as part of a research project designed and implemented by Oak Ridge National Laboratory (ORNL) and co-funded by the U.S. Department of Energy (DOE) and the Tennessee Valley Authority.

The project serves as a linchpin in a broad array of research programs at ORNL that strive to address America's most energy-inefficient sector: buildings.

Appetite Control
Americans work, live and play in boxes of brick, wood, glass, steel and concrete-artificial environments typically kept at constant temperature and lighting levels regardless of season or time of day and notwithstanding the presence or departure of the occupants. The results are obvious. In the United States, buildings command 40% of the nation's overall energy use, ranking above both industry, at 32%, and transportation, at 28%. Buildings demand 71% of domestic electric power in the U.S. and 55% of the nation's natural gas-and produce 43% of U.S. carbon emissions.

"Creating more energy-efficient buildings is not only part of the overall solution but is the number one most cost-effective opportunity to reduce the nation's energy consumption and affect climate change," says Jeff Christian, a buildings technology researcher at ORNL and coordinator of the Habitat for Humanity project. "Yes, we must replace oil with biofuels. Yes, we must pursue other supply-side solutions in an environmentally acceptable manner. But there is enormous potential to reduce energy demand in the buildings sector, and that is by far the cheapest solution if we really want to address this problem."

Because the nearly 5 million commercial buildings and 112 million households use a collective 38.8 quadrillion BTUs of energy each year, curtailing consumption is a tall order but has enormous potential. Space heating and cooling and ventilation demand most of that power, followed closely by lighting, then water heating. Refrigeration, electronics, computers and other items add up to their own significant and growing slice of the energy pie.

Buildings' appetite for energy has been on the rise as a result of natural population growth and related development of homes, apartment complexes, shopping malls, schools, office buildings and healthcare facilities. The amount of energy required for each person occupying those buildings is climbing as well.

Residential floor space per capita in the U.S. is growing, driven by construction of larger homes as well as a decline in the average number of occupants, and the number of power-hungry accoutrements to be found in today's households—from computers to video games to plasma televisions—is on the rise. As a result, residential energy consumption, unless aggressively addressed, is expected to grow 1% per year until 2025.

On the commercial side, energy use is projected to increase an average annual rate of 2% between now and 2025, driven primarily by use of computers and other office equipment. Such growth has placed stress on aging infrastructure, which, coupled with weather incidents that include the feisty tornado and hurricane seasons and record-breaking heat waves of recent years, result in periods of peak demand and power outages that hamper business and boost energy costs. Soaring prices for natural gas and petroleum also contribute to the problem, and experts believe this combination of factors has created a critical mass, driving the nation toward long overdue adoption of energy-efficient technologies and construction practices.

"If we continue to construct the same kind of inefficient buildings that put high demands on the power grid, we will have to build additional supply-side infrastructure to serve them," says Patrick Hughes, leader of ORNL's buildings technology research program. "What we need is to fundamentally change the way we approach the construction and operation of our buildings. If done right, we, as a nation, can have our cake and eat it too. We can spend less going forward on buildings and supply-side infrastructure and vastly reduce the energy consumption and climate changing emissions of the built environment."

ORNL researchers are supporting a DOE initiative to develop affordable, net-zero-energy housing by 2020 and zero-energy commercial buildings by 2025. To achieve this goal, scientists and engineers must break broad new ground in every aspect of building construction and operating practice, Hughes says.

Whenever affordable, these high-performance buildings must be outfitted with renewable sources of energy, minimizing the demand for fossil fuels such as natural gas reserves or coal-fired power plants that supply electricity to the grid. Whether heat pump systems that tap geothermal energy in the ground around the building, solar panels for residential developments such as the Lenoir City Habitat community, combined heat and power systems for commercial buildings or a range of other up-and-coming technologies, the ultimate goal is to construct buildings that can support their own energy needs in a way that is affordable, sustainable and energy efficient.

At ORNL, researchers have been plugging away at the problem since the energy crisis of the 1970s, when U.S. DOE predecessors began funding research into energy efficiency initiatives. Through the work of pioneering researchers, whose message regarding the U.S. environmental impact of energy consumption was not always popular, ORNL demonstrated the potential for energy efficiency long before the term became a buzzword.

Today ORNL participates in a number of programs that intersect with builders and suppliers in an effort to bring new energy-efficient technologies and construction supplies to market. Laboratory researchers have worked with industry to develop and demonstrate energy savings benefits of infrared-blocking pigments used to make dark-colored metal, concrete tile and asphalt shingle roofing that is highly solar reflective, reducing the need for air conditioning. ORNL has worked with industry partners to develop low-cost, more energy-efficient second- and third-generation foam insulation materials.

The Laboratory has developed software tools to assess the potential for moisture-related damage in construction materials; provide energy efficiency ratings for entire buildings; audit homes for weatherization as part of DOE's low-income Weatherization Assistance Program and perform analysis to support the design of more efficient heat pumps and other equipment. In addition, ORNL has helped guide development of standards related to insulation, materials that make up a building's envelope—that is, walls, floor, ceiling, roof, windows and doors-and moisture design.

While government researchers have been focused on energy efficiency for a number of years, the construction industry and homeowners have been slower to embrace change. Pat Love remembers when the Laboratory began promoting the expertise of DOE laboratories to homeowners in 1980. ORNL serves as the lead national laboratory in communications for the Building America program, a public-private partnership that conducts research and sets standards for energy-efficient homes. In this capacity, Love attends a number of trade shows and seminars each year, armed with educational pamphlets on how energy efficiency can be incorporated into building design and construction.

"People did not stop by our booth," she says. "They were suspicious of the government. They did not care about energy efficiency. They cared about cost." In the early 1990s, the program began targeting homebuilders rather than homeowners, offering guidance and training on energy-efficient building practices. That effort produced greater results, but, still, many in the industry have been slow to change their ways.

The past three to four years, however, have marked a detectable shift, driven by the very consumers who largely ignored the Laboratory's early efforts. A new demographic, the baby boomers—armed with disposable incomes, looming retirement and a sense of social responsibility remnant from their former hippie days—is creating demand for "green" construction incorporating energy-efficient and renewable energy technologies and building practices. Love says she receives a steady stream of queries from people looking to renovate or build a home and asking questions about energy efficiency.

Larissa Brass, senior science communicator at Oak Ridge National Laboratory, writes and edits articles for the ORNL Review and other internal and external publications. 

This article was adapted from the original that first appeared in the ORNL Review, and was republished with permission from Oak Ridge National Laboratory.

Part Two: A Glimpse of the Energy Future

Just 50 miles west of Oak Ridge National Laboratory (ORNL) off Interstate 40 near Crossville, Tenn., 6,000 acres of woodland are about to be transformed into the kind of community that Jeff Christian once only dreamed of. Developers based in Overland Park, Kansas, have reached an agreement with ORNL for collaboration on Walden Reserve, a "green" residential development that would feature technologies tested and developed by ORNL's Buildings Technology Center.

"I have noticed that when I tell people that these new houses have energy costs of approximately 50 cents a day, they tend to think about their own homes. People respond to the idea. They just need education and awareness."

-- Jeff Christian, ORNL, buildings technology researcher