PERSONNEL FILE . . . The Metropolitan Washington Mortgage Bankers Association has installed its 1983 offiers. They are: Charles R. Montgomery of Koones & Montgomery Inc., president; William A. Middleton of Weaver Bros. Inc., first vice president; John A. Sarget of the Randall Hagner Co., second vice president, and Richard K. Juergens Jr. of the Frank S. Phillips Mortgage Co., secretary/treasurer . . . The Metro Area Council of Red Carpet Real Estate has also chosen officers. Paul Brown of Al Smith Real Estate, Fairfax, is the new president; Joanne Darling of Darling Real Estate, Bladensburg, vice president, and Beverly Poss of Monocacy Valley Realty, Frederick, secretary-treasurer . . . Patricia Addington has joined Keyes Condon Florance Architects as marketing administrative assistant. In addition, the firm has named Thomas N. Eichbaum and Philip A. Esocoff associate partners.

IN THE BUSINESS . . . Total sales of new homes, town houses, condominiums and the like in the metropolitan Washington area hit 1,500 units in December, the highest total for that month in a decade, Housing Data Reports notes. Although December, which is usually a poor month for sales, trailed other months in 1982, it was up 43 percent from 1981. Total net sales for the year were 23,600 units, up 25 percent over '82 and 15 percent over '81, HDR says . . . Three local firms have won "Build-ability" awards, given by the Subcontractors Council of the Suburban Maryland Home Builders Association. The small-volume award went to Oxford Development Co.; the medium-volume award to William L. Berry & Co. Inc. and the large-volume honors to Porten-Sullivan Inc. The builders were rated on such criteria as supervision, quality control, ethics and quality of material used . . . Meetings, seminars and classes coming up: Two members of the area financial community will speak on Monday at a Northern Virginia Apartment Association dinner. C. Patrick Nolan of DRG Financial Corp. and David W. Hodges of General Electric Credit Corp. will discuss the present situation and future trends in financing multi-family properties. For information, call 671-6777 . . . The Northern Virginia Builders Association will sponsor two seminars beginning March 2. One will be on land development in residential construction, the other on residential construction supervision. Information: Larry Sexton at 893-6800 . . . Washington area Chapter 18 of the American Institute of Real Estate Appraisers will sponsor an income capitalization workshop Feb. 28 through March 2. Information: Barbara White, 628-4494.

ON THE MOVE . . . Coldwell Banker-Routh Robbins Realtors is opening its 20th office in the area, this one in Dale City. The new facility was formerly Homeyer & Bachman Realty Inc. . . . The Fred Ezra Co. has been appointed exclusive leasing agents by the law firm of Arent, Fox, Kintner, Plotkin & Kahn to sublet 34,000 square feet of office space in the Washington Square building at 1050 Connecticut Ave. NW. Arent, Fox leased 145,000 square feet in the building but currently occupy only 111,000 . . . Sunrise Technology Park II Associates has obtained a $450,000 second trust land acquisition loan through The Abacus Group for 5.3 acres in Reston. The parcel will be used for a 100,000-square-foot research and development building.