Enjoying the benefits of open protocols
Published: 10 November, 2004
Open systems are good news for the end users of building-management systems, as ROB HEMMERDINGER explains.
The Holy Grail for users of building management systems has always been the ability to enable different systems to ‘talk’ to one another — to integrate all the functions of a building into one seamless system.
The development of open systems data communication protocols for building-automation and control networks makes that dream a reality — and the benefits to the end user are huge.
To put it simply, open systems provide enhanced usability, lower installation costs and greater control of life-cycle expenditure.
Open systems allow products with the best capabilities to be chosen for the task in hand. the result is a more effective BMS solution, which is not held back by proprietary software.
For this reason, suppliers of building-management systems support open-system protocols. Andover Controls and its sister company TAC, for example, have developed the use of market-leading open system protocols BACnet and LonWorks.
Developed over the last 15 years, LonWorks can interface with a wide range of systems — from hotel booking to home-automation systems. LonWorks is probably the most common open system found in modern buildings.
BACnet is a fast-growing protocol viewed with greatest interest in the USA and the Pacific Rim. New products are appearing on a regular basis, and it can operate over a wide choice of communications media.
Multiple vendors use BACnet. It is ‘freely’ distributed, and the protocol is independent of any hardware or software — making it suitable for a very wide range of applications.
Compared to BACnet, LonWorks is a ‘lighter’ protocol and can therefore be added to smaller and more cost-effective devices.
Open-system installations have been completed in many buildings — public and commercial. The Queens Park Hospital in Blackburn, for example, will soon be home to a large BACnet BMS solution to be installed by Andover. It will consist of 32 air-handling units, six heat stations, some 120 BACnet inverters, two BACnet chiller controllers, one BACnet boiler sequencer and a Continuum access control system.
However, the use of open protocols is not limited to the UK. The Fortunoff Department Store in New York is already benefiting from an integrated BACnet building-management system. Installed by T. M. Biers during the summer of 2003, the solution controls multi-stage gas fired heating, air-handling units and exhaust fans. Over 3000 are points monitored and controlled by the BACnet system.
LonWorks and BACnet can perfectly complement each other within an open system. For example, BACnet could be in use at an existing site, and the end user might later want to incorporate LonWorks devices as well. In this circumstance, LonWorks could easily be added to the offering to provide a higher level of interoperability.
With the addition of native BACnet to its entire line of Continuum facility automation controllers, Andover now integrates all building functions into single, BACnet-compliant systems.
‘Native’ BACnet means systems work seamlessly with those of other suppliers’ BACnet devices without the need for special protocol converters — saving on initial system configuration and ongoing maintenance.
BACnet systems provide the user with true, single-seat control of an entire facility— via a dedicated front end or, increasingly, remotely via a web browser.
Either way, a graphical menu system and dynamic colour graphic screens paint a clear picture of conditions throughout the facility. This allows users to complete any number of tasks — all through the one interface.
Taking advantage of an open protocol platform has both economic and operational benefits. Overall, it is estimated that a 10% saving can be made on construction and finance costs through the use of an integrated events-driven BMS solution.
The cost of maintenance can be reduced by up to 10% over a 25-year period, and facilities managers benefit from total control over their building’s utility costs.
Using an existing network also reduces installation costs — especially when adding extra functionality to the building as the system develops. Viewing all building systems from a single front end saves on the IT budget.
Working with a supplier which provides a range of products with an open protocol reduces maintenance and training administration and costs. From an administration point of view, dealing with a single point of contact when organising training schedules or agreeing maintenance programmes saves time and resource.
The BACnet and other protocols can be combined with proprietary equipment to build up a complete system —that can also be accessed over the Internet using a web browser.
Whatever the application, there is a suitable open protocol available. Whether that choice is BACnet, LonWorks or any other, the ultimate winner in the development of these open systems is the end user.
For this reason, support for them all by a manufacturer provides interoperability between all types of devices and a strong, common platform to manage facilities proactively.
Rob Hemmerdinger is with Andover Controls Europe Ltd, Smisby Road, Ashby-de-la-Zouch, Leics LE65 2UE.
More about BACnet
A solution white paper from Andover Controls ‘BACnet without limits’ describes it as the ‘most capable of open protocols’. Of the protocols Modbus, N2, LonMark and BACnet, only BACnet is developed in an ‘open’ manner.
All are used by multiple vendors and all but LonMark are freely distributed protocols that are chip and software independent.
BACnet was developed by an ASHRAE (American Society of Heating, Refrigeration & Air Conditioning Engineers) committee and first released in 1995. It has been regularly updated in response to emerging technology and the demands of end users.
The 2001 version added IP controller addresses and other networking enhancements.
At the beginning of January 2003, the International Standards Organisation adopted the BACnet protocol as a communications standard for integrating building-automation and control products.
Developments in progress include XML capability and web services to provide access to building systems and services such as weather data, human-resource information etc.
While all the protocols above offer data sharing for read/write points, BACnet and LonMark go much further. Both offer device management. They also offer scheduling, trending, and alarm and event management — but BACnet’s capabilities are more powerful than those of LonMark.