Sen. Dale Bumpers (D-Ark.) will be the keynote speaker at the fourth annual Energy Technology Confeence & Exposition which opens Monday at the Sheraton Park Hotel. Bumpers, a member of the Energy and Natural Resources Committee, will speak on energy and today's economy. The exposition, free to the public, will include exhibits of energy-saving devices for homes as well as industry. These include working models of solar homes, hand-held devices that detect and measure heat loss and a variety of controls for saving fuel and reducing pollution.

An office building with retail shops on the first floor and a restaurant on the second will be constructed on the northwest corner of 17th and R streets NW. A group headed by Jeffrey N. Cohen has purchased the site. Dunn & Preston are the architects. Brannock Associates will handle leasing.

Sandy Andrews has joined the staff of A & A Realtors of Springfield as assistant sales manager.

B'Nal B'rith plans to build a new wing on its eight-story center at 1640 Rhode Island Ave. NW. The expanded building will feature a conference hall, an enlarged museum, a research library and a public chapel. Carl M. Freeman, a Montgomery County developer and builder, has been named chairman of the fund-raising campaign which seeks to ralse $500,000.

"The Marketing of Metropolitan Washington: The Case for Economic Growth in the Suburbs" will be the topic for discussion Thursday at a meeting of the National Capital Area chapter of the American Institute of Planners. Winfield Kelly, Prince George's County Executive, will be the speaker at the noon session at the Center for Adult Education at the University of Maryland. The program is open to the public. Call 223,6800, ext. 402 for luncheon reservations.

Free programs on how to finance, maintain and research older homes will be held March 19 and 26 at the Laurel branch library and the Hyattsville branch library, respectively from 9 a.m. to 4 p.m. To register, contact Prince George's County Memorial Library System, Adult Services Office, 699-3500, ext. 266.

Walker & Dunlop, Washington-based mortgage bankers and realtors, has arranged a $775,000 land sale/leaseback through Connecticut Mutual Life Insurance Co. for the new Westpark apartments at 2130 P St. NW.

Twenty-eight new condominiums will be added to the original 52 units at Canal Woods on Tony Tank Lake in Salisbury, Md. Completion of the luxury units is scheduled for the spring of 1978. The Ahtes & Hanna Group, Reatlros, in Salisbury, is handling sales.

Robert V. McGrath, president of Carriage House Associates, Inc., has become a member of United Referral Service, a nationwide referral and relocation system on sales and rentals.

The appraisal of farms in developing areas, marinas and commercial properties plus the proposed uniform eminent domain code will be the subjects for discussion Tuesday at a meeting of the American R/W Association and the Association of Federal Appraisers at the Friendship International Hotel. The meeting begins at 10 a.m.

Marta Mustain, Roger Smith and Sanday McAllister were recognized as Mount Vernon Realty's outstanding agents "over the long haul" at a dinner held recently in Crystal City. Millie Sydnor and George Webb were named "rookies of the year."

Long and Foster, Inc., has opened its 16th office. The newest is in Park Center at the corner of Commerce and Holly Streets, Sterling Park. The manager of the office, which has 12 sales associates, is William C. Mathers.

A $240,000 recreation complex is under construction in the Fox Mill Woods subdivision adjacent to Reston. The tennis courts are scheduled for completion by May 1 and the swimming pool by May 31. Architect for the Mill Woods Swim and Tennis Club is Taylor Garvin Associates, Restion. The builder is Lipnick Construction Co. of Washington.