Is there a way to add an additional thermostat in an office building?
While it makes sense, it's probably not possible without MAJOR expense, though it's probably worth some investigating to get a ballpark on just how difficult or expensive it might actually be for your specific case.

If there's one thermostat for the whole floor (or suite of offices) there's probably only one heating/cooling zone for the whole floor (or suite of offices.) Zoning a system that was not set up with zones (smaller areas controlled by individual thermostats) after the fact is rarely easy or cheap.

You could perhaps move the thermostat, but then the office it's in now would be cold...that might be OK if you move the person who likes it coolest in there, and it keeps most of the other folks happier - if your office politics allow for that sort of arrangement.