The design of today's Building Automation Systems favor "open" platforms that allow for systems and components from different manufacturers to share information. The benefits of this are readily apparent and highly desirable to building owners, operators and builders. In the past, different building systems such as security, HVAC and lighting were totally independent of each other and operated as individual islands of control and the sharing of information was accomplished through hardwired connections or custom written software drivers and gateways that allowed information to be translated and shared between systems. Although this method is still widely used today its limited capability and added cost make it a mediocre solution at best. Another drawback to the standalone system is its ability to only communicate with components developed by a single manufacture. This proprietary nature of these systems typically results in costly repairs, maintenance and expansion due to a lack of choices.
In contrast an open control system is designed to:
Allow systems to seamlessly share information which reduces the total number of devices, resulting in an overall decrease in installed cost. For example, a single room occupancy sensor notifies the lighting control system, HVAC system and security system of the presence of occupants. Each respective system would take the appropriate action based on this information, i.e.; the lighting system would index the lights on or off, the HVAC system would impose setback temperatures (if the area was vacant), and the security system would provide alarm annunciation if an intruder was detected during unoccupied periods.
Capitalize on system infrastructure. Installing several independent systems creates duplication of devices as well as infrastructure. From the above example, a single room occupancy sensor takes the place of three. Independent, non-integrated systems also utilize individual user interface PCs, and communication risers all performing discrete individual tasks. Once all system components operate from a common networking platform and "speak the same language", a single user interface and network infrastructure can serve all building functions.
Eliminate proprietary systems and promote competitive pricing. Building owners can take advantage of competitive forces when multiple vendors and suppliers are bidding a project. Unfortunately, when a proprietary system is installed this purchasing power usually disappears after the initial installation. Often a sole source vendor can demand his price and may even provide the customer with less then satisfactory service. The utilization of open protocols allows owners to continuously and competitively purchase system expansions and service.
With the desire to eliminate a vendor's proprietary position and more easily share information, the building controls industry recognized the necessity and desire for standardized protocols and networking platforms. Although many standard protocols have been proposed, BACnet® has emerged as the one that is being widely accepted by building owners, manufactures and consulting engineers in the building controls industry today. Released in 1996 BACnet® was developed by the American Society of Heating Refrigeration and Air conditioning Engineers (ASHRAE) to allow different systems to share information and allow for a single seat user interface.
BACnet® is "a data communication protocol for building automation and control networks". A data communication protocol is a set of rules governing the exchange of data over a computer network. The rules take the form of a written specification that spells out what is required to conform to the protocol, everything from what kind of cable to use to how to perform a particular request or command in a standard way.
The advantages of system integration are clear and the market has evolved to a point where integrated projects can be cost effectively implemented. To learn more about BACnet® contact us or visit the following web sites.
www.bacnet.org
www.bacnetassociation.org
And to learn more on how BACnet® works check out this tutorial.
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