The Washington Gas Light Co., unable to supply gas to new customers here since 1972, has made commitments to 11 builders in Northern Virginia because of new availability of gas. The Builders, who have commitments for 1,909 hookups, plan to build 466 houses this year. Total Virginia commitments for gas connections in new dwellings total 3,300. paul D. Young, of Washington Gas Light Co., said that availability soon will be extended to 4,300 new houses in Maryland. Earlier this week the D.C. Public Service Commission approved a WGL request to serve 3,000 new customers in the District. Subdivisions of single-family houses to be gas-served in Virginia include Raceway Farms, Towlson Meadows, Pinewood Mills, Country Club Manor, Colvin Glen and Wood Edge. Town house users will be Circle Woods, Dale City, Huntington at Mount Vernon, Lafayette Park West III and Dunn Loring Village.

Barbara Bach and Marilyn Lacy, who have been active in real estate sales in Montgomery County for some years, have established Designing Women, a Potomac firm that will build houses. They are starting with a the rehabilitation of a concrete bolck house on a wooded half-acre with a view of Great Falls Park. Bach and Lacy are redesigning it into a contemporary dwelling that will have skylights, a glassed-in kitchen and a redwood "hot tub." Mortgage banker Leonard Gatti arranged the financing for the acquisition and renovation.

George W. DeFranceaux, the mortgage banker who heads the National Housing Partnership, is back at work after major surgery.

Statistics from the multiple listing service of the Northern Virginia Board of Realtors indicate that total residential sales in April in that area exceeded those in that month in 1977 by more than $52 million, hitting a total of more than $160 million. That's a dollar volume increase of nearly 50 per cent. In April, 2,295 units were sold, compared with 1,585 a year earlier.

Edward C. Heard Jr., the new manager of Town & Country's Woodlawn office, is still remembered by colleagues, friends and residents of one Northern Virginia subdivision as the "pumpkin man." That's because last October he bought and delivered 950 pumpkins to each house in an area from which he frequently got listings and made sales. He left a business card with each pumpkin and continues to get referrals and listings from his Halloween promotion. A retired Army colonel, Heard has been with T & C since 1975.