United Technologies' Building Automation subsidiary has reached an agreement with Charles E. Smith Companies to provide integrated building systems and electronic tenant office services at two Northern Virginia office complexes.

The two companies claimed that the agreement could make the Crystal Gateway Three in Crystal City and Five Skyline Place at Bailey's Crossroads among the most automated office complexes anywhere.

The Smith Companies said the agreement might be expanded to all of the firm's major projects in the Washington area, about 12 million square feet of commercial office space.

Building Automation is to provide system design and installation of essential services, such as elevators, heating, ventilation, air conditioning, lighting, telephones, fire and security systems and communications services.

But further it is to include services such as word processing, data processing, electronic mail, computer graphics, telecommunications and high-speed copy-printing on a sale or lease basis through a central office.

The two office towers are to have talking elevators that also display time, weather and news reports as they announce floors and other messages, such as telling people not to block the door or that the elevator is full.

The integrated system will be operated by a "data highway" made up of a network of fiber optic cables, which collects thousands of pieces of information that is sent to a central computer "brain" that will make decisions for the entire building, said Anthony D. Autorino, president of Building Automation.