Using BACnet in building automation
BACnet is constantly evolving and embracing new technologies, such as wireless networking and Smart Grid applications.
By Mike Phillips, Southland Industries, Dulles, Va.
Over the years, many articles regarding the ASHRAE-135 BACnet International standard have appeared, featuring everything from its advantages, success stories, and comparison with the LonTalk protocol, to the latest products that are compliant with the protocol standard tested by BACnet International. But beyond all the marketing hype for new products, where are we really with BACnet today? What new applications are succeeding, how can engineers take advantage of those proven technologies, and what is on the horizon? As a consulting specifying engineer, what do you need to know about the current direction of BACnet?
BACnet’s role in sustainable buildings
One of the most exciting areas of development is the way BACnet is being used in facilities to bring together products, information, and energy savings to create an environment where facility managers can actually manage information about their facilities. Back in the early days of electronic controls, the systems we programmed and installed were often called EMCS, or energy management and control systems. Beyond a clock-like scheduling function and a sequence referred to as an optimized start, which executed the most effective start-up sequence, these systems did very little to manage or control energy consumption and facility operating costs. The three basic requirements to manage energy are to measure, analyze, and control it. That means metering, creating reports that are actually useful in presenting data, and active control strategies to assist building owners in running buildings more efficiently. BACnet is making it easier for these tasks to come together.
BACnet energy meters: Several meter manufacturers now market BACnet power meters and BTU meters. These types of meters make it much easier for information connectivity back to building automation systems (BAS) so that they can be used to extract and report relevant consumption data. Even better, the choice to install energy dashboard software or energy consumption analytics software over the existing controls front end of facilities with older, proprietary systems is made easier if the building has been retrofitted with BACnet-ready energy meters.
Energy dashboards: Most energy dashboards fall into two basic categories: those that connect directly to energy meters as a stand-alone product and those that connect to both the metering and its associated systems through an existing building automation system. The BACnet protocol is becoming a huge factor in the market of third-party energy dashboards.
Third-party dashboards must retrieve data from various control systems and controlled devices. Some of the more sophisticated dashboards offering usage analytics and fault diagnostic detection (FDD) may require hundreds of data points, which presents some challenges if using proprietary protocols. BACnet, as a standardized protocol, takes a lot of the guesswork out of such interfaces due to the auto-discover capability, allowing easier integration of points without a lot of custom programming. In fact, BACnet has made it easier to open up a whole new market segment in third-party software as a means to assist building owners and operators with the information required to make real reductions in energy consumption.
BACnet advanced operator workstation: One recent feature of the BACnet standard that will make the energy dashboards mentioned above, as well as any BACnet-based automation system, more open in the marketplace is the introduction of the BACnet advanced operator workstation standard (B-AWS). This standard allows BACnet workstations to create, configure, and manage a whole host of BACnet properties that exist in other BACnet-compliant systems. This is a huge step in moving forward toward the ultimate goal of having one front-end interface package for the daily facility management of buildings with systems from multiple vendors. Considering there are seven manufacturers that now meet the new standard, consulting engineers may want to explore how they may incorporate the B-AWS standard within open protocol specifications.
Smart Grid: As part of the Energy Independence and Security Act of 2007 (EISA), the National Institute of Standards and Technology (NIST) was given a mandate to coordinate Smart Grid interoperability standards. With Internet protocol-ready capabilities and a role in so many aspects of the building control system, BACnet has emerged as a big part of that standard. As a result, ASHRAE formed the Standard Project Committee SPC 201P in conjunction with the National Electrical Manufacturers Assn. and has proposed the Smart Grid interoperability standard known as the Facility Smart Grid Information Model. The purpose of this standard model is to define a working standard for building control systems to be able to communicate necessary information back and forth between utilities and energy-consuming devices within facilities.
In July 2011, the Dept. of Energy signed onto the development of what is being proposed as ASHRAE/NEMA Standard 201. For BACnet, this means additions to the protocol will most likely be made in the form of new objects designed to take advantage of Smart Grid technologies such as OpenADR—a kind of advanced form of demand response control that allows BAS to automatically make decisions on how to shed load, based on more specific demand and pricing structures. Think of it this way: Instead of a building operator being notified of a demand response opportunity and then having to sift through energy pricing, rate structure, and potential demand charge penalties, the Smart Grid will be able to determine exactly how much load should be shed for how long, and then accomplish that response automatically.
New products listed every month
One way to discover new BACnet products emerging within the market is to survey the additions to the BACnet Testing Lab product listings (BTL Listings). The BTL is the official testing laboratory supported by the BACnet International, certifying specific products that can demonstrate adherence to the BACnet standard. In review of last year’s 2011 certifications, 89 new products were added. These products range from variable frequency drives, lighting controllers, and software products to unitary controllers for small HVAC equipment.
As an increasing amount of products achieve the right to display the BTL mark on a regular basis, those interested in BACnet should check the website listings for new manufacturers or products from time to time. While not all new products are officially listed, it is a good way to gauge growth in the acceptance of the standard.
Those paying attention to either BACnet or wireless technology news in the past months may have noticed the September 2011 press release by the ZigBee Alliance concerning the establishment of the first BACnet-approved standard for wireless mesh sensors in commercial buildings. What does this mean for building owners and specifiers? For starters, as more wireless products come on the market, competition will increase and pricing should level off. One of the hardest decisions for construction contractors and estimators has been evaluating the reduced cost of the installation labor of wireless devices with the increased hardware cost of the devices themselves, making a wireless option less attractive for some projects. As these hardware costs come down, wireless can be seen as a viable option for many more types of facilities.
A secondary advantage is to create more interoperability at the field sensor level. Many networked sensors from the various BAS controls manufacturers use proprietary protocols at the sensor level, even if their overall network is BACnet. This standard will help break down that barrier and allow users to employ a sensor from manufacturer A even if the zone controller is from manufacturer B.
The potential of wireless, however, is even more exciting. Research is being conducted on BACnet/IP (BACnet over Internet protocol) as a possible future direction for BACnet wireless communications between field controllers. This would function similar to current Wi-Fi networks and would allow for the greater amount of data present in controller-to-controller communications to be efficiently integrated into a single network.
BACnet is a continuously evolving standard. Researchers and manufacturers are taking steps to fulfill the promise of a truly open and intelligent building every day. The goal was always to make it something more than merely devices from different manufacturers sharing common information. One can stand at the edge and begin to see that we are truly on the brink of a revolution in the way we manage our facilities and their control, energy consumption, and pretty soon, the way future facilities collaborate with utilities for the benefit of the entire world community.
Mike Phillips is a senior controls engineer with Southland Industries, and has more than 16 years of experience in the digital control and HVAC automation industry. He has designed BAS for a wide variety of specialty buildings including large-scale data centers, hospitals, laboratories, school building complexes, and process facilities.
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