Construction is about to start for a new Guest Quarters apartment-hotel facility at 2500 Pennsylvania Ave. NW. not far from another Guest Quarters at 801 New Hampshire Ave. NW.An early April start is scheduled, a spokesman for the general contractor, Donohoe Construction Co., said.

The 126-unit, 10-story building was designed by Aland Lockman and Associates for developer Florenz Ourisman, who also built the New Hampshire Avenue facility several years ago.

The new $4 million Guest Quarters, expected to be completed in the spring of 1978, occupies a site on which old dwellings, with commercial space on the first floor, were razed recently.

The Donohoe firm also is handling the constructions and development of the 220-room Holiday Inn of Georgetown at 2101 Wisconsin Ave. NW. It is expected to be completed late this year and the Donohoe firm will move into space on the first floor.Motel Management of America will operate the motel-hotel.

The Donohoe firm also has nearly completed the $30,000 square foot office and commercial space building called 4200 Wisconsin (Ave. NW), where the Norwegian Embassy already is occupying 12,000 square feet. The building also will contain a theater, a post office and shops.

Under way in the Rock Spring development on Democracy Boulevard near Old Georgetown Road in upper Bethesda is the 122,000 square foot Champagne building, which Donohoe is building for developer Charles Camlier.

The new structure is a sister building to the six-story, free-standing Camalier building that was completed several years ago. Occupancy of the new building is scheduled late this year.