BACnet/IP is the ISO standard communication protocol over the IP network for multi-vender building automation systems. Since the system consists of many devices from variety of manufacturers, it is very important to predict the traffic performance in the case of actual operation on the site. This research developed a BACnet/IP traffic simulation model for the object access services from the HIM （Human Interface Module） to the ICONT（Intelligent CONTroller） on heavy background traffic. The simulation compares the two BACnet object implementation methods, that is, the Distributed Controller method and the ICONT method in the case of the total accesses of 1000 object read services with the background traffic of the BACnet COV （Change Of Value）broadcasts and the IP stream traffic.
