BACnet 'opens' the gates to interoperability.
By Mark Bevill
Building owner/operators today deal with a very complicated world that stretches from indoor air quality (IAQ) to energy deregulation. Many of these issues will be addressed using an information network via the traditional building automation system (BAS). Given the importance of the BAS, there are several choices an owner/operator must make when selecting a new system or expanding a current one, including:
- Selecting a vendor that supplies a proprietary system.
- Selecting a vendor that offers a proprietary system with gateways.
- Installing a system using the new "open" protocols, such as LonWorks or BACnet.
When choosing to work within a proprietary environment, a number of pitfalls must be considered. One is that using a proprietary system will lock an end-user into that vendor's offering for future changes or additions. These offerings vary from new hardware and software to the associated services provided by the exclusive vendor.
As anyone in business knows, more options mean greater flexibility in the selection of services and pricing. Although a proprietary solution may be the least expensive solution when expanding or upgrading a system, it also may not be the best solution for the long-term viability of the BAS.
A second choice is to use a vendor that offers a proprietary system using gateways. A gateway is simply a translator that allows two dissimilar systems to communicate. Gateways have been promoted by several major vendors as the answer to the issue of open systems. These gateways, however, are expensive to both supply and support.
Given the nature of a gateway, it is most likely proprietary on one side and may or may not be proprietary on the other. Since a gateway is proprietary on one side, end-users are still "locked-in" to that vendor's offering.
Additionally, a gateway increases both the sophistication of the system and the cost of maintenance. Why? Vendors on each side must agree when they change software versions, so the gateway is still compatible on both sides. Some vendors promote the capability of using gateways with hundreds of systems, which can cause support problems.
A final choice is to upgrade or purchase a new BAS, using an open protocol. The question then becomes, "which one?" Consider the following about the BACnet open protocol:
- BACnet was developed in a public forum by users, vendors, and engineers under the aegis of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), Atlanta. BACnet is published by ASHRAE, and may be used free of charge.
- The BACnet protocol was developed by ASHRAE for building automation.
- BACnet is scaleable and can be used for small or very large networks.
- BACnet is being implemented by nearly all vendors at high-end environments, and by some at low-end environments, fulfilling both needs through one language.
- BACnet can only be modified or enhanced through ASHRAE after a complete public review.
- BACnet is an American National Standard Institute (ANSI) government standard.
BACnet and 'Native' BACnet.
There is much confusion presented to owner/operators by the building automation industry concerning BACnet. The fact is that nearly all major vendors implement or will implement BACnet at some level. The question then becomes, "At when level?"
BACnet was designed to be a scaleable protocol, which means it can be used for both low-level and high-end control using high-speed networks. "Native" BACnet means that BACnet is being implemented at all levels. Without "native" BACnet, the true benefits of BACnet can never be realized.
These benefits include:
- Not dealing with gateways.
- The ability to get a third-party organization to service the complete network.
To realize the total benefits of BACnet, "native" BACnet is the BACnet of choice. ~
Mark Bevill has been an ASHRAE member since 1984 and is president of Automatic Building Controls Inc., Rolling Meadows, IL, a building automation systems integration company.
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