More than $1 billion worth of new buildings has been completed, started or announced in downtown Washington during 1978, the Metropolitian Washington Board of Trade said in its latest report on downtown progress.

The new construction is described as a renaissance for the city by the board of trade's new president, developer Oliver T. Carr, whose own firm, Oliver T. Carr Co., is the biggest private developer of new downtown projects.

In the square mile of Northwest Washington between Pennsylvania Avenue on the south, M Street on the north, 15th Street on the east and North Capital Street on the west, the board of trade report counted 35 private projects and 16 public and institutional improvements containing:

5,300 hotel rooms.

2,600 housing units.

8.2 million square feet of offices.

1.3 million square feet of stores.6 million square feet of public facilities.

By the board of trade's estimates, the new downtown projects should create 50,000 additional permanent jobs for metropolitan Washington area residents.

The projects on the board of trade's list range from the National Gallery East Wing building and the Dolley Madison Hotel-both opened this year-to the downtown campus of the University of the District of Columbia, the D.C. Convention Center and several others whose construction is still in doubt.

Total construction cost of the projects is $1.3 billion, but that includes projects still in the "proposed" stage and some requiring action by Congress, zoning authorities and other agencies that could turn thumbs down.

But board of trade officials say they consider the listing conservative beacause only projects that have been announced by developers or land owners are counted. Not added into the $1.3 billion total are a number of proposals still in the talking stage and some that have been announced since the list was compiled last month.

The multi-million-dollar office building at Pennsylvania Avenue and 12th Street NW that Cabot, Cabot & Forbes of Boston recently announced plans to build is not on the list, nor are several other projects in the Pennsylvania Avenue Development Corp. area.

PADC Director W. Anderson Barnes predicts that within the next 18 to 24 months private developers will unvell plans for projects on all the blocks on Pennsylvania Avenue west of the Federal Bureau of Investigation building. Barnes estimates those projects could bring more than $150 million in additional private development, pushing the downtown total toward $1.5 billion.

Already on the drawing board or under construction in the PADC project area are about $200 million worth of projects: the $50 million Willard Hotel renovation and expansion, the $110 million hotel and office building on the National Press Building block to be built by Marriott Corp. and Quadrangle Development Corp., the adjacent $18 million American City building being built by Quadrangle and the Cabot, Cabot & Forbes building.

The biggest "if" on the board of trade list is the $99 million D.C. Convention Center, which has won the approval of congressional budget watchers but now is being challenged by foes who want the project submitted to votes in a referendum.

Almost one-third of the 50 projects are considered "spinoffs" from the convention center, and some of them could be shelved, revamped or delayed if the center is not built.

Owners of properties at 10th Street and New York Avenue, 8th and K Sts., 8th and H Sts. and 7th and K Sts. have announced vague plans for hotels or hotel and commercial projects that are dependent on construction of the center.

The District's Redevelopment Land Agency is completing negotiations now with two developers for one of the biggest projects on the list, development of the land stop the Metro Center subway station con G Street.

Most of the $200 million Metro Center complex will be built by the Oliver T. Carr Co., currently the most active developer downtown. Carr is developer for a $57 million retail and office complex that will occupy the rest of the block where the Garfinckel department store is located and is building the $14.5 million American Society of Association Executives headquarters at 1575 Eye St. NW.

Encouraged by city efforts to spur city living and keep downtown streets active with permanent residents, developers are planing a score of residential projects in the neighborhood.

The biggest is the housing "superblock" that PADC wants to build atop a gaint storage building for the National Archives covering four blocks bounded by Pennsylvania Avenue, 7th, 9th and E Streets NW. The archives project alone will cost $150 builing and the 750 housing units atop it would push the total price past $200 million.