Construction has begun on the new corporate headquarters for Baltimore Federal Savings and Loan Association at the city's Inner Harbor. The new building will be located in the block bounded by East Lombard, South, Water and Commerce streets. The new headquarters is scheduled to open May 5, 1984, Baltimore Federal's 100th birthday.

The building will consist of 20 stories with 348,375 square feet of banking, office and retail space, and 164 parking spaces. Baltimore Federal will occupy approximately one-half of the office space.

The building will incorporate the historical facade of a structure built in 1894 at 301 Water St. for Merchant's National Bank. Baltimore Federal had acquired the 301 Water St. location in 1977, after the building had been vacant and unused for seven years.

In addition to the granite walls, other historical and artistic elements are being preserved from the original structure and will be incorporated in the new building, including delicately wood-carved panels of the original board room and an Italian classical floor mosaic.

Recent developments in commercial leasing in the Washington metropolitan area:

* Metropolitan Services Group has leased 1,200 square feet of space in the Saratoga Building at 11820 Parklawn Dr. in Rockville.

* Solar Science Industries Inc. has leased 2,300 square feet of space in the Cheverly Industrial Park on Lydell Road in Cheverly.

* Wibbies Inc. has leased 3,200 square feet of space at the WWDC Industrial Park on Seminary Road in Silver Spring.

* The law firm of Reichelt, Nussbaum & Brown has leased 7,800 square feet of space at the Maryland Trade Center at 7500 Greenway Center Dr. in Greenbelt. In the same building, Lockheed Engineering and Management Services Co. Inc. has leased an additional 2,000 square feet of space. Lockheed already occupies two complete floors at the Maryland Trade Center.

* Howard University has awarded a contract to Donohoe Construction Co. to build a $3 million parking facility for Howard University Hospital at 5th and V streets NW. The five-story structure will contain 135,000 feet of space and is scheduled for completion by November 1983.