A new program geared to build more-energy-efficient houses and to slow the overall growth of utility costs in Northern Virginia has begun under the joint sponsorship of Virginia Power and the Northern Virginia Builders Association.

Sponsors of the Energy Saver Home Program, which sets strict guidelines for participating builders to follow in constructing houses, hope to certify about 4,500 new houses in Northern Virginia as energy efficient.

For buyers, the program will offer houses that are up to 35 percent more energy efficient than conventional models built to state codes, saving their owners about $300 in energy costs a year. These houses also will be more comfortable and will have higher resale value, according to John Oyhenart, Virginia Power's senior energy services representative.

Oyhenart said that lenders are recognizing that energy-efficient houses have lower utility costs, thereby giving their owners more disposable income. As a result, some lenders will give larger mortgage loans to buyers of energy-efficient houses, and will approve loans for buyers with borderline income levels and first-time buyers.

House buyers also are offered a one-year warranty that will provide them with up to $500 if a builder fails to meet the energy-efficiency requirements.

For builders, the program is designed to help them sell more houses, give them a better reputation and help with advertising costs, according to Harvey Sorum, chairman of NVBA's energy committee. Print and radio ads have been developed that builders can use, and the program will reimburse builders for some of their advertising costs.

Sorum acknowledged that while most consumers are interested in energy efficiency, some local builders might not participate in the new program because sales are going well and they might not see a reason to change their practices.

"Homeowners are demanding quality, and with that quality comes energy efficiency," Sorum said, as he discussed the new program with about 50 Northern Virginia builders at a meeting earlier this week.

He added that the program also can help stave off further building regulations. "We can prove to the world that our industry can do this on a voluntary basis, and that we're not going to have any state or federal regulators telling us how to run our business," he told the group.

Thomas O'Hara, an Alexandria builder and an NVBA energy committee member, told the builders group that energy-efficient houses built under the program would add about 1 to 3 percent to the cost of a home, but that customers will be willing to pay that amount.

"People can appreciate the extra expenses in buying an energy-efficient house because they usually make it the added expense up in two to three years," he said.

Both groups have had energy-rating systems in Northern Virginia for several years. Virginia Power, which has about 440,000 customers in Northern Virginia, has audited 7,000 homes since its program began in 1983, while NVBA has audited 10,000 to 15,000 homes since 1979. The joint sponsorship was arranged in part to alleviate confusion by house buyers over the existence of the two similar programs. Officials added that their new joint program also offers stiffer energy-conservation measures.

The program sets specific requirements for insulating ceilings, walls, floors, heating and cooling ducts and areas such as garages and basements. Windows must be double glazed or single glazed, if they are storm windows, and doors must be insulated. Weather-stripping is required in certain areas, and the home's heating and cooling equipment must meet specific energy requirements.

Virginia Power inspects each prospective energy-program home twice to ensure the builder has complied with its requirements.

The utility hopes the program will benefit all its customers by lowering peak energy consumption and delaying construction of a new power plant that could cost between $1.5 billion and $4.5 billion, according to a utility spokesman.

About 10 builders have signed up for the new program, and Oyhenart hopes to convince the 90 builders who were participating in the recently expired Virginia Power energy program to join the joint plan with the builders' group.