When Frank Crawford finished poking his head into the attic, shining his flashlight into nooks and crannies of the basement and inspecting more than 100 other spots, he knew that although John and Edna Stark's home was "pretty energy efficient," they could reduce their heating bill further.

And the Chevy Chase couple listened carefully, as Crawford explained ways -- from insulating the home's water heater to adding caulking around windows -- they could trim their natural gas and electric bills. "The bills have gone up as everyone knows, and that raises the preminum on preventing heat loss," Stark noted.

Crawford is an energy auditor for Potomac Electric Power Co., and his energy-saving recommendations -- good for summer as well as winter energy bills -- were made as part of a Pepco program that analyzes in depth Washington-area homes' cooling and heating efficiency.

The service, mandated by federal law and costing $ 15, is popular among Pepco's customers as winter and high heating bills draw near. Crawford and Pepco's three other Energy Department-certified auditors are booked for six weeks, with each inspecting two homes a day. The visits average 2 1/2 hours. The utility is currently training two more auditors.

Similar inspection programs are operated by other utilities in this region, including Washington Gas Light Co., Potomac Edison Co., Baltimore Gas and Electric Co., and Southern Maryland Electric Cooperative Inc.

Virginia Electric Power Co. plans to offer the service in Northern Virginia after it finishes a pilot program in the Fredricksburg area, spokesman Jim Buck said. A free, less-thorough inspection has been available to Vepco's customers for three years, he said.

Pepco, Baltimore Gas and Electric and Potomac Edison also offer to analyze homes' energy use and to suggest improvements based on information provided by customers in a questionnaire. Pepco's service is free, while Potomac Edison charges $ 5, and Baltimore Gas and Electric charge $ 3. A similar service is available free from the Virginia Polytechnic and State University Extension Service.

Pepco offers its audit to customers in detached houses, town houses and apartments -- except for garden apartments and those in buildings of more than four units -- in Maryland, the District and Northern Virginia. The other utilities' service is available only in Maryland, although Washington Gas and Potomac Edison spokeswomen said their audits will be expanded later to other customers.

Except for Baltimore Gas and Electric, the companies are limiting the audits to selected neighborhoods, with more areas added each month. Customers, eligible if they use gas, electricity, oil or another fuel for heating, are notified when the service is available.

About two weeks after Crawford has inspected a home from basement to attic, the customer receives a detailed report, showing the recommended improvements: do-it-yourself and contractor costs, annual savings on energy bills and how long those saving will take to pay for the conservation steps.

Included in the report for Pepco's Maryland customers are state-compiled lists of contractors licensed to do the improvements and of banks and savings and loan associations willing to accept loan applications for conservation. In Virginia and the District, Pepco supplies lists of insulation contractors and lenders. Customers also are told of federal tax credits for conservation and of government aid for low-income families.

"In the audit, we don't tell you what to do," said Eric M. Oganesoff, manager of Pepco's residential energy services department. "All we're trying to do is to tell you what is the most cost-effective thing to do. You may have no insulation in your ceiling, but you go out and buy storm windows. That's not cost effective, and we try to point that out."

Pepco began offering a less thorough audit in January 1978 to help conservation-minded customers save more energy and, as a result, slow the growing demand for electricity and help avoid the need for new, expensive power plants, he said.

In July, Pepco expanded the scope of its audit and lowered its fee (from $ 25 to $ 15) to meet the federal law. Baltimore Gas and Electric started its detailed audit in November 1980 after five years of a less complete service. The Washington area's other utilities were prompted by the law to begin their audits this summer.

In the three years Pepco has offered audits, it has inspected about 4,000 homes and analyzed about 6,000 more through use of the questionnarie, Oganesoff said. Twelve thousand more customers asked for the questionnaire this summer, although only 10 percent to 12 percent are expected to return the form, he said. Washington Gas workers have audited about 500 homes since the firm began the service in September and have 500 more scheduled, spokeswoman Susan J. Butz said.

Oganesoff guessed that more of Pepco's 300,000 residential customers have not requested audits because "this is a pretty intelligent community, and I think a lot of people are aware of conservation measures and have done some of them already. I think a lot of people believe their homes already are energy efficient."

To see how many customers heeded the auditors' advice, Pepco surveyed 300 in May 1979 and found slightly more than half had made some improvements, he said. The study showed that customers did the work themselves in nearly all of the questionnaire-analyzed homes and in about half of the auditor-inspected houses. The rest hired contractors.

At the Starks' 2,304-square-foot, one-story rambler, Crawford methodically checked such things as caulking, vents, weatherstripping, drapes, and if the living room fireplace had a glass enclosure. It didn't, and he suggested one. "A fireplace sucks out more heat than it gives off,' he said. "If you have an enclosure, you still get the radiant heat."

In the mostly finished basement, Crawford focused his flashlight on a window "See those gaps [around the window]; they need to be caulked," he said. "Caulking and weatherstripping are cheap, and I feel that they pay for themselves during the first heating season you use them."

Outside the house, built in 1955, he found storm windows on all but two windows -- "that's good" -- and a door in need of weatherstripping. "A lot of minor problems like this will add up to a major one," he said as he walked on to check another door.

He pulled a solar gauge out of a bag and squinted through it to measure the sunlight the house receives -- 70 percent for the southern wall, but its windows are too small to benefit from the solar heat. The roof is warmed by 90 percent of the sun, and Crawford noted the Starks could install a solar water heater, but the payback would be lengthy.

Back inside the home, Crawford, a 17-year Pepco veteran, removed the plate of a wall electrical outlet to probe the wall's insulation. He found 3 1/2 inches of insulation and deemed that sufficent.

In the basement, he tested the 26-year-old furnace's efficency, and it rated at 71 percent. "That's pretty good for the age of this thing," he later told the Starks. "You could get a new one, but it probably wouldn't be worth the cost. That's pretty good for a gas furnace."

"What about the attic?" Stark asked.

Crawford suggested adding insulation to the four inches of loose rock wool already in the attic. While Pepco favors recommends that attic insulation have an R-value of 30 -- the Starks' attic rated at R-12.6 -- that level is "not real critical because you reach a point of diminishing returns," he said.

With the extra insulation, the audit estimated, the Starks could save $ 18 to $ 26 during the first year at an installation cost of $ 380 to $ 641 by a contractor or $ 260 to $ 320 if they did the work themselves. Their investment could pay for inself in 10 to more than 20 years, depending on the installation cost, according to the audit.

Improvements that might pay for themselves in one to two years, if the Starks installed them, are a clock thermostat and water heater insulation -- a "jacket" available in hardware stories. The thermostat could save $ 33 to $ 50 a year, and the water heater jacket $ 13 to $ 20 annually, the audit showed.

Twelve other possible improvements also were broken down in the audit report by their savings on the Stark's annual energy bill: $ 420 for heating and $ 175 for air conditioning payback and installation costs.

For the Starks, they were reassured by Crawford's favorable assessment of their home's energy efficiency. Stark said he had been concerned with the effects of the attic, furnace and fireplace on the couple's energy use and had requested the audit to help him decide how to improve the home. He said he expected to implement those recommendations he could afford.

For more information, call Pepco at 872-4626; Washington Gas, 750-5671; Potomac Edison, 997-2002; Southern Maryland Electric Co-op, 274-3114, ext. 67; Baltimore Gas and Electric, 298-1800; and Virginia Tech Extension Service, 558-2475. Vepco customers should call their local office. CAPTION: Picture, Pepco energy auditor Frank Crawford measures the glass area on a house. Analysis costs homeowners $ 15, By Gerald Martineau -- The Washington Post