Metering: Traditionally, meters have been read manually or connected to the BMS by counting pulses. A much more cost effective solution is to network the meters using Modbus or M-bus. Inverters: Danfoss and ABB drives both support Modbus, and ABB also supports BACnet — making it possible to interface their inverters to a BMS using a bus connection to the controller/outstation, rather than hard-wired using physical inputs and outputs. With a bus connection, extensive additional data can be recorded, such as speed, frequency output, current, torque, voltage, energy consumption, and faults with error codes. VRV systems: Variable refrigerant volume (VRV) systems for air-conditioning have grown in popularity in recent years and offer easy communications with a BMS via Modbus, BACnet or LonWorks — either over RS485 or IP. Open-system checklist Most companies have an IT network infrastructure based on TCP/IP, so why not make use of it. It would be a missed opportunity and a waste of financial resources not to let the building control system utilise that investment by either offering access to the BMS across the IT network or allowing the BMS to communicate between its outstations via the network. Involve the people responsible for IT and show them what the building-control system can do, how easy it can be to connect a device on the network with an address and how that device can be accessed from any PC. Concerns voiced over network security are often the result of lack of knowledge; in reality the BMS will have little influence. Indeed, the security measures applied to modern IT infrastructures will prove beneficial to the BMS as well as its network. When specifying a BMS, make sure that it can interface using open and universally available protocols. Also, make sure that this applies to third-party products and systems. Select meters with Modbus or M-bus, VRV systems that can communicate over Modbus or BACnet. Ensure that users can access the whole system from any PC on the IT network, enabling the day-to-day running of the building to be more effective and efficient. Standardisation or open system? There are at least eight different types of open protocol actively used in today’s building-control projects, even without counting wireless standards. These protocols are often complementary and used to integrate different sections of the system. The question, therefore is not which of them will be the one and only de facto standard but, rather, the opposite. The more likely event is that the client will ask for, and suppliers and installers will offer, the integration of a multitude of different systems and sub-systems using a number of these open protocols, rather than trying to agree on one specific protocol. Anders Norén is managing director of Priva Building Intelligence Ltd.