How to Specify BACnet-Based Systems

BACnet is an ANSI/ASHRAE standard that specifies a common communication protocol that allows building systems to communicate with each other using a common language. By implementing BACnet, systems made by different companies can communicate with each other. This technology provides the building owner with more choices when it comes to choosing and integrating whole building systems, and even individual building automation components when new automation systems are to be installed or added to a building or campus-wide system.
There are a number of issues that must be considered when specifying a BACnet-based system. These issues focus on selecting BACnet options, which include system architectures. A very important choice in the selection of system architecture is whether or not to allow a gateway to a non-BACnet-based system, or system components, and how to specify this BACnet gateway. The basics of any control system also must not be forgotten; that is, the sequence of operations of the equipment, in addition to the look and feel of the control system.
Specifying a BACnet system cannot by done by simply stating "System shall use BACnet communication protocols." This is a very ambiguous statement that can result in a system that has a completely unexpected architecture. It is very important to give details regarding architecture and system expectations when specifying a BACnet-based system.