By Katherine Salant
Saturday, December 31, 2005

For some decades now, the government has been exhorting us to build houses that consume less energy. The rationale has changed over time from reducing dependence on foreign oil imports to lowering utility bills to reducing summer peak-load electricity demands that cause brownouts.

We now have another reason to build houses that use less energy -- reducing global warming and greenhouse gases.

Many homeowners assume that the emissions causing the problem come from cars, trucks and industrial smokestacks. But in the United States, the largest source of carbon dioxide emissions, which account for 85 percent of all greenhouse gases, is buildings. And half of these are houses.

An easy way to grasp the scale of this problem is to think in terms of cars.

Every year, the amount of emissions attributable to each house in America is equivalent to that of two cars driven 10,000 miles each, so with about 80 million houses out there, this is 160 million cars' worth of pollution, said Ren Anderson of the National Renewable Energy Laboratory in Golden, Colo.

We depend on fossil fuels to live in our houses. These fuels produce carbon dioxide, as well as small amounts of other greenhouse gases such as methane. For heating, our furnaces run on natural gas or oil and vent the smoke up the chimney. For cooling and everything else in our houses that requires energy, we depend on electricity. About half of our electricity is generated at coal-burning power plants.

To address the residential emissions issue, the Department of Energy's Building America program has set the goal of reducing energy needs in new houses by 50 percent within the next 10 years. This would reduce their carbon emissions by 50 percent.

Anderson, who manages research for the Building America program, said this ambitious goal can be achieved with some modification to conventional building practices and the adoption of some newer building products that are widely available. But he also acknowledged that success requires that his program do more than encourage home builders to participate. It must also engage the buyers of new houses because the house itself accounts for only 42 percent of the energy used. The rest goes to operate all the appliances, computers, entertainment equipment and gadgets that are part of households.

For buyers who want to save energy, the first purchase for a new house should be Energy Star appliances, which many builders now offer in their base-priced houses. On average, major appliances consume about 16 percent of a household's energy consumption; Energy Star appliances reduce this. Buyers can make additional energy cuts by purchasing Energy Star models of other items, such as televisions and computers. Since its inception in the early 1990s, the Energy Star program has grown to more than 40 product categories.

Lighting is another energy drain that buyers must tackle. It consumes about 12 percent of the average household's total energy use. This can be cut by two-thirds simply by switching out incandescent bulbs for Energy Star compact fluorescent lamps that screw into standard incandescent bulb sockets. Though more expensive upfront, these bulbs last up to 10 times longer than standard incandescent bulbs. The latest generation has been color-corrected to produce the same quality of light.

To increase the energy efficiency of the house itself, Anderson's group has worked with builders, manufacturers and building scientists around the country to develop strategies for different climates. New products and building practices are tested in pilot projects and deemed cost-effective before they are recommended to home builders.

Some changes require minimal modification to conventional building practices; in other cases, the learning curve is steeper, though "definitely not insurmountable," Anderson said.

Anderson's suggested changes to the house are not free, though. On average, he said, they add about $10,000 to the cost of a 2,500-square-foot, two-story, four-bedroom house.

Many of Anderson's recommendations simply increase the efficiency of standard house parts. The windows should not only be dual-paned but also should have a low-e, or low-emission, coating, which keeps heat inside in winter and out in summer. Many, but not all, builders now offer this as standard. The walls should be framed with 2-by-6 studs so that more insulation can be added. To prevent heated or cooled air from escaping, air leaks should be conscientiously plugged. A gas furnace should be a 90 percent or higher fuel-efficiency model because it converts gas to heat more efficiently and thus uses less. (This also means a lower gas bill.) All home builders are now required to provide a 13 SEER (seasonal energy efficiency ratio) air conditioning compressor; Anderson recommends an even more efficient 15 SEER model.

All ducts should be sealed with mastic, a gray, gloppy substance, instead of tape, which eventually disintegrates and allows as much as 25 percent of heating and cooling energy to be lost. Anderson also recommends putting all ducts in the living area instead of in the attic, a standard practice in many parts of the country. Although attic ducts can be insulated, significant heating and cooling losses will still occur because the insulation only lowers the loss of energy; it doesn't eliminate it. When the ducts are included in the "conditioned space" (for example, inconspicuously run along the ceiling), their energy losses will pass into your living area, not outdoors. Additional energy can be saved by placing a furnace in the center of the house to shorten duct runs.

Anderson's other target that is built into the house is hot water. This necessity of modern life consumes 12 percent of total household energy because it is stored in a large tank that is continuously heated. Anderson would halve this with a dual strategy: a solar water heater that supplies about 30 to 40 percent of a household's needs and a tankless hot water heater that heats water as needed for the balance.

Pulling back for the big-picture perspective, Anderson said Building America's goals are a moving target. As new products and building practices are tested and found to enhance energy efficiency, the program will push for more energy savings.

In a separate interview, David K. Garmon, an undersecretary at the Department of Energy, emphasized that reducing greenhouse-gas emissions is not the only benefit of the program: New-home buyers would also enjoy significantly lower utility bills and greatly increased comfort.

How soon will a Building America house be available in your market? Many builders, both large and small, have participated in Building America's programs since the Energy Department started it 10 years ago. To date, about 30,000 houses have been built. More builders will participate when they sense that buyers are serious about energy efficiency.

When buyers pass up granite countertops that will impress their friends and relatives today for energy efficiencies that will make a better planet for their children and grandchildren tomorrow, home builders will join the Building America program in droves.

Katherine Salant can be contacted at http://www.katherinesalant.com.

2005 Katherine Salant Distributed by Inman News Features