The Kaiser Permanente Health Care Program has announced plans to build a new medical center on a 4.6-acre site at the intersection of Connecticut and Perry avenues in Kensington.

The new facility will replace the health-care group's existing medical office locations on Summit Avenue and Concord Street. Its 85,000 square feet will house offices for 48 physicians in addition to other clinical and office space.

Construction of the medical center is scheduled to begin early next year, with completion expected by mid-1987. The architectural engineering firm for the project is Cannon/Faulkner of Washington.

Construction is being financed through the sale of $24 million in tax-exempt bonds, a portion of which also is being used for leasehold improvements on Kaiser Permanente's new Baltimore-area offices.

Other recent developments in commercial realty in the Washington metropolitan area:

*Spaulding and Slye announced the following leasing transactions: Children's Hospital National Medical Center has signed a 10-year lease for 21,334 square feet at 8737 Colesville Rd., Silver Spring, where it will relocate its executive offices. New York Life Insurance Co. has signed a five-year lease for 18,537 square feet at Tysons Executive Plaza, located at 2000 Corporate Ridge, McLean.