arduino ip

Hi,

I'm working on a project contains 16 uno to control the access system of 16 elevators. The distance between UNOs varies from 10m to 80m. The problem is when I add or delete access cards number to the UNO code I go to each uno individually and connect it throuh usb to arduino Windows software and program it, now I'm thinking to make the system more advanced by connecting the 16 UNOs on the building network (bacnet/op) and access the code of each uno from a central station by means of graphical user interface.
what is the simplest way to do that?
Should I think of having a 3rd party protocol converter (RS232 to bacnet ip), or the Ethernet shield is enough??

Thanks