The London-based practice, which is working with Bartlett offshoot Space Syntax, is drawing up plans for three floors of Camden's famous Art Deco building, Greater London House.
The facade of the former cigarette factory is something of a landmark in the local area, and has been listed at Grade II.
Spacelab, a RIBA Award-winner, has worked on a number of other Emap buildings including the headquarters of Metro FM in Newcastle.
The practice's collaborator, Space Syntax, emerged out of the Bartlett and has over recent years developed innovative software that tracks people movement within office environments.
Spacelab expect to be on site in mid-February, with completion by mid-July.