Long & Foster, Inc., realtors, opened its 17th office recently at Van Ness Street and Wisconsin Avenue NW. The firm, which has other branches in Northern Virginia and Maryland, reported that it sold 660 houses with a total value of more than $41 million in April.

The National Corp. for Housing Partnerships announced that William A. Schainker has been promoted to president of Housing Capital Corp., a subsidiary, and Brooks R. Palmer to president of Capital Homes, Inc., also a subsidiary.

Energy utilization and conservation will be the topic Monday evening when Larry Logan, manager of the Virginia office of Kolb Electric, speaks at a dinner meeting of the Northern Virginia Apartment Association at the Ramada Inn in Arlington.

Gibson Realty & Management Co. announced that Xerox Corp. has leased 112,000 square feet in the Fleet Industrial Park in Franconia.

Del. Walter Fauntroy, who represents the District in Congress, will be the speaker Tuesday evening when the Lambda Alpha land economics fraternity holds its annual formal banquet on the roof terrace of the Hotel Washington in downtown D.C.

Greenhoot, Inc., announced that the industrial building at 1423 Leslie Ave., Alexandria, has been sold to Noble Instruments, Inc., for approximately $200,000.