For 70 years, or thereabouts, the apartments at 2029 and 2101 Connecticut Avenue NW have been regarded as prestige rental addresses. The large building, 2101, was resold awhile ago and a slow to cooperative ownership begun. A number of residents have continued to rent, however. Now, across the street, the 25-unit building at 2029 is reported to be on the verge of sale and possible conversion to condominium or co-op ownership. One tenant of a big apartment in 2029, mortgage banker George W. DeFranceaux, head of the National Housing Partnership, has been trying to get some facts for weeks - to no avail. He admits that the fine old building needs some work and that some of the rents are much too low in today's market. But he and his wife are not interested in buying - they already own one place near St. Michael's, Md. So they now are looking for another almost-as-large, well-located apartment. And $1,000 a month doesn't faze them.

-Texas-based Centex Homes Corp., which has attracted many area home buyers to its fast-moving Winston Knolls subdivision in the Springfield area of Northern Virginia in the past two years, now is planning to build on 300 lots it has acquired inside the Beltway in the McLean area. Traditional models are expected to be shown this summer, at price of more than $100,000.

-The National Housing Conference, Inc., based here, has established the Carl Coan Sr. Award that will be presented annually for outstanding service to housing and community development. The award is named for the late, long-time staff director of the Senate subcommittee on housing and urban affairs, who died in December.

Preliminary work has started on a new, 208,000-square-foot office building at 1900 I St. NW. Potomac Electric Power Co. sold the 27,747-foot site for $3.8 million to Square 118 Associates, which includes Quandrangle Development Corp. and Square Realty, Inc. Salus Corp. will build the structure, designed by Weihe Black, Jeffries and Strassman. A plaque on the completed building will note that the 19th Street Baptist Church formerly stood on the site, fulfilling a promise made by Pepco when it acquired the property some years ago.