HOME SALES IN Northern Virginia jumped 14 percent in September compared with the same month last year, although the average price remained virtually unchanged, the Northern Virginia Board of Realtors reports.

Of 1,435 units sold, 155, or 11 percent, were condominiums, and the average price for these was $73,050. The average price for houses was $108,700, and the overall average was $104,800. That overall average was down $200 (.001 percent) from September 1983, the board said.

"The market seems to be holding its own on a year-to-date basis, which makes 1984 every bit as good a sales year as 1983," it said.

SAVINGS AND LOANS reasserted themselves in the mortgage market in the second quarter of the year, data collected by the Department of Housing and Urban Development indicate. Loans closed by S&Ls on one- to four-family homes jumped 37 percent in the quarter, while originations by commercial banks dropped 16 percent and those by mortgage bankers declined 11 percent.

The results gave S&Ls 51 percent of the market -- which totaled $59.1 billion -- in the quarter, while mortgage companies took 25 percent and banks 16 percent.

HUD's report did not analyze the figures, but industry observers pointed to the increased popularity of adjustable-rate mortgages, which reduce the lender's risk from interest rate rises, as the principal factor in the S&L resurgence.

FHA and VA loans accounted for 7 and 6 percent of the market, respectively, the report said.

It also noted that total mortgage debt outstanding amounted to $1.749 trillion, of which $1.102 trillion was for one- to four-family homes.

REPS. RON WYDEN (D-Ore.) and Richard A. Gephardt (D-Mo.), who have been pushing legislation to ease investment by pension funds, last week joined House Majority Leader James C. Wright (D-Tex.) in urging the Labor Department to accomplish their bill's goals with regulatory changes.

The congressmen note that about $700 billion is controlled by private pension fund managers, and if they can be encouraged to invest some of it in mortgages, it "will mean benefits for home buyers and pension fund participants."

Such investment is discouraged by a number of existing regulations, which Wyden and Gephardt hoped to override with their bill. The legislation died with the adjournment of the 98th Congress. However, Wyden said last week that he feels the department is receptive to the idea of increased pension investment in mortgages and is hopeful that his and his colleagues' letter to Robert A. G. Monks of the Office of Pension and Welfare Benefit Programs will have an effect.

IN THE BUSINESS . . . Fairfax County has awarded Lane Construction Co. an $899,000 contract to build the Holmes Run dam that will produce a 16-acre lake at New Providence, a planned community now under construction between Routes 50 and 29/211 in Fairfax. Builders, including Edw. R. Carr, Pulte, Ryan and Halle, are planning about 600 homes there . . . An 18-acre estate owned by Stephen Turner in Frederick is to go on the auction block on Wednesday. The property includes a five-bedroom, six-bath, 8,300-square-foot house designed by Hugh Newell Jacobsen, and a swimming pool, bath house and tennis court. The Louis Traiman Co. of Philadelphia will handle the auction . . . CEI Construction Inc. of Bethesda is now the seventh-largest general contractor in the nation, according to the monthly Building Design & Construction . . . Leigh & Schwab Realtors of Washington and Frazee Associates Inc. of Rockville have become members of the Better Homes & Gardens Real Estate Service . . . Aiming for the "higher-end single-family move-up market," Martens/Edward Development Co. is offering 55 four-bedroom units on two-acre lots in Darnestown. Houses in the project, known as Haddonfield, are priced from $275,000 to $295,000, and range from 3,225 to 3,468 square feet . . . Manufacturers Life Insurance Co. (Manulife) has begun construction on a 12-story, 241,000-square-foot office building at 1850 M St. NW. Completion is set for next fall.

PERSONNEL FILE . . . Dewberry & Davis has promoted William H. Edwards to director of branch offices . . . James E. Matthews has joined the Baltimore-based firm of O'Conor, Piper & Flynn as head of Oak Investment Corp. Inc. . . . Metropolitan Partnership Ltd. has named Jeffrey K. Hayes vice president of finance. CAPTION: Picture 1, Twelve-story office building at 1850 M St. NW on which Manufacturers Life Insurance Co. has begun construction; Picture 2, One of 55 homes being sold at Haddonfield project in Darnestown. million, up 1.3 million from last year, according to a report issued yesterday by the U.S. Committee for Refugees.

People fleeing Afghanistan and Ethiopia -- both with pro-Soviet governments -- account for more than half of the increase from 7.8 million worldwide in 1983 to 9.1 million this year, the report by the private nonprofit group said.

An estimated 3.66 million have left Afghanistan, where Soviet troops and the government they support are fighting guerrillas. Last year, the figure was put at 3.3 million. In 1982, Afghanistan's total population was 15.1 million.

"Pakistan continues to welcome with widely praised generosity the 2.9 million Afghan refugees estimated to have fled to that country since the Soviet invasion of Afghanistan in 1979," the report says.

Three-quarters of the refugees are said to be women and children, living in 340 villages supported by the United Nations High Commissioner for Refugees.

In Africa, Ethiopian refugees are estimated to have risen to 1.21 million, from 883,000 in 1983.

About 700,000 are in neighboring Somalia, their numbers increased by drought and what the report calls "the reluctance of Ethiopian authorities to facilitate the distribution of relief supplies in Tigre and Eritrea" provinces. The Ethiopian military government, newly reorganized with a dominant Communist Party, has been fighting rebellions in these areas for decades.