Optimizing building automation system performance

Nearly all industrial facilities have a building automation system (BAS) of some kind. The question is: How well are they using it? The answer, unfortunately, is that in most cases plants are not applying these assets to their full capability.

08/01/1998


Nearly all industrial facilities have a building automation system (BAS) of some kind. The question is: How well are they using it?

The answer, unfortunately, is that in most cases plants are not applying these assets to their full capability. The good news, however, is that they can. Thanks to the flexibility inherent in these systems, coupled with advancements in computer and communications technology, the latent power of a BAS can be harnessed for increased performance and efficiency.

Building facilities are extraordinarily complex, many handling hundreds of thousands of data points. Today, nearly all plant equipment and systems are controlled -- from chillers and boilers to power monitoring and processes.

For the plant engineer, managing responsibilities of this magnitude in an ever-changing environment can be done efficiently only with a computer-based system. Modern BASs offer much more assistance than systems of the past. In addition to monitoring operations, they gather data, perform trending and analysis, provide precision control for heightened efficiency, run on their own without a lot of support or day-to-day interaction, and have become one of the first places plant engineers can turn to diagnose problems.

As sophisticated technology adds greater capabilities to the BAS, plant engineers are finding it pays to move beyond a "let it run until there's a problem" approach to using these systems to improve their business (see "Moving beyond scheduling and monitoring"). Issues range from providing a comfortable environment to in-door air quality and refrigerant management policies to meeting business objectives at the lowest energy costs. Owner/supplier relationships are no longer just service a-greements, but business relationships designed to solve business problems in a competitive, global workplace.

Historical perspectives

What is a building automation system?

Definitions vary, but nearly all term a BAS to be a collection of equipment from sensor to software, blended together to achieve a seamless flow of data and control actions. Specific components may include end devices, controllers, networks over which data are transferred, and an information path to front-end operator interfaces. A BAS also embraces control and information strategies that allow it to function effectively.

Historically a relatively new plant system, the BAS originated about 30-yr ago, growing as control needs became more critical and energy supplies became more expensive. The traditional perspective was to conserve resources through simple scheduling, apply direct digital control (DDC) to plant HVAC systems, and react to emergencies.

Fueled by the Arab oil embargo, early energy management systems had limited application. They functioned as elaborate time clocks designed to limit runtime and control energy costs. By the late 1980s, they had progressed to schedulers with some advanced strategies, and have now become established DDC systems, maintaining performance and coordinating plant systems.

It is the additional data from DDC control that have led plant engineers and systems operators to recognize how valuable these systems are for troubleshooting and diagnostic applications. And as developing standard network protocols open these systems to more extensive application, plant engineers are recognizing the potential of the BAS and seeking to extend and refine its use.

Tapping untapped capacity

Few BASs are leveraged to full capacity. The system installed in new construction often receives only cursory attention, lost in the overwhelming volume of tasks required at startup. Although every BAS is capable of helping make more intelligent decisions, significant savings may be lost unless collection mechanisms are established to gather data and time is taken to analyze the data. Reports containing such data are typically available, but may not be used unless they can be compiled effortlessly.

It is never too late to optimize a system, even one that has been in place for a number of years. Help is available from a variety of sources.

Most BAS vendors suggest an annual audit of building performance as a means of uncovering ways to improve performance and increase efficiency. For plants with insufficient staff to perform such surveys, system suppliers can provide assistance for a fee. Recommendations typically center on sequencing activities on the basis of the way a facility actually operates versus the way it was expected to run initially or prior to a modification.

Impact of technology

Today is a time of transition for BASs. Issues such as standard network protocols, linking of sites around the globe, systems integration, and moving into the millennium (see "Will your BAS be working in the year 2000") all have impact on the operation and application of the plant BAS.

Standard and interoperable

Perhaps the area experiencing the greatest change is that responsible for communicating information from one component to another. The development of standard network protocols in response to user demands for more freedom of choice in control systems and components is furthering the concepts of standard and interoperable. BASs that once controlled single plant operations are being linked over local and wide area networks across the plant and multiple sites.

Standard protocol specifications (LonMark and BACnet are two examples) are designed to permit products from a variety of manufacturers to communicate at the device level on a peer-to-peer basis. A standard protocol lets a BAS exchange information simply and economically, avoiding complicated proprietary or third-party gateways. Although technology allows most anything to be linked with specialized bridges, routers, and interfaces, it is easier and more economical to adopt a standard for your BAS that works optimally for your application in the first place.

As with any technology, however, standardization involves tradeoffs. Diverse products in a single system raise questions about service responsibilities, and while installing a different vendor's device at every point in the system might yield the lowest cost, it likely will also incur the highest system life-cycle and maintenance costs.

Interoperable solutions are not a panacea. A standard protocol helps ensure that components obtained 2 yr from now will work with others on the system purchased earlier because the protocol remains constant. Or, if changes have occurred, they are documented to allow upgrades to take place in a predetermined fashion. Formats and procedures are not identical. For example, it is not possible today, and probably will not be in the near future, to simply connect disparate controllers and have them work together.

Remote monitoring

Remote monitoring is yet another challenge to the architecture of the BAS. Once again, technology to accomplish such tasks is available, but it must be thought through carefully. Although the capability can be added later, it is easier to build it into the BAS initially.

Among the most important considerations is determining if it is the operator or the facility that will be remote. A BAS configuration that controls many sites from a central location is different from one in which many operators monitor and control a single site from many places.

Systems integration

Another fast-growing phenomenon impacting on BASs is integrating intelligent equipment controllers. Thanks to standard protocols and rapid data transmission, it is now technically feasible to link a variety of plant products and systems. Functions from fire and security to equipment such as boilers, chillers, and variable speed drives can be linked to the overall BAS. It is conceivable that in the foreseeable future everything with a microprocessor-based unit controller will be linked to the central BAS, bringing together into a single front-end interface data that influence management decisions about how a building operates.

In addition to traditional controls contractors, a new player has entered the field: The system integrator. Typically independent controls contractors affiliated with one or more BAS suppliers, these companies take responsibility for the entire system, including the BAS and the functions it controls. Because of their networking knowledge, they are able to create a fully interoperable system.

Usable and reliable

Although defining, specifying, and installing the BAS are important functions, two critical, but often overlooked parameters inherent in the day-to-day operation of the BAS, are usability and reliability. A shortage of qualified technical personnel makes the need for usable, smart, transparent operator interfaces mandatory. A system must accommodate simple and fast training of the workers who must perform BAS control and data acquisition.

Five primary activities are generally performed by BAS operators: Review system status (temperature, pressure, and flows); handle comfort calls (modify temperatures, pressures, and flows/ change settings); respond to alarms (equipment off line, parameters out of range, and device failure); schedule use (occupancy of space); and generate historical information (trending and reporting).

Look for systems that offer information screens that present this information clearly using simple yet lively graphics. Other distinguishing features to watch for that promote ease of use are standardized applications, templates, and comprehensive standard report and analysis functions. The fewer custom routines needed, the better.

Reliability is also an issue. A BAS must work when needed. For example, a system that monitors and controls expensive machinery and a $1 million/day process must be capable of bringing equipment back online after a power failure in the right sequence, at the right ramp-up frequency, without creating a demand peak for the next 12 mo. Sophisticated BASs can be configured to allow a single piece of machinery to be taken off line for maintenance without interrupting the sequencing of the rest of the equipment.

DDC technology has had a marked influence on both the reliability and usability of BASs. At the equipment level, its flexibility opened the door for custom sequencing of equipment. Its abilities to achieve precision control enable machinery such as chillers to maintain temperatures at close tolerance and allow the equipment to be protected more effectively from adverse conditions.

For example, a DDC controller detected surge in a chiller occurring because the water entering the machine was too cold for it to run properly. The condition was detected by the microprocessor; the controller then held the operation of the machine at a level where surge could not occur.

A less sophisticated electromechanical or pneumatic control either would have let the machine continue to run in surge, or it would have detected the condition and shut down the machine. In this case, the system detected the condition, generated an alarm, and remedied the problem temporarily until it could be fixed.

Next frontier

What does the future hold for the plant BAS?

Beyond interoperability and integration is the transparent Human/Machine Interface (HMI). Today, technology could allow a BAS to take total systems control. In an ideal situation, all operations are brought back to a single operator station and viewed in a common manner regardless of function or system. Such integration of all functions into the same front end would advance ease of use even farther.

Advancements in artificial intelligence and expert systems will simplify the building operator's job and optimize the operation even more. Tools being developed today will allow automatic fine tuning of overall system performance tomorrow.

Partnering will undoubtedly increase as the industry seeks to build the expertise it needs to achieve the functionality its users demand. Only time will tell how this expertise will be grown and applied. Although BASs and the benefits they provide have come a long way, they've really only just begun. Network protocol standards have only started to help these systems interface to the IT world efficiently and effectively. DDC technology has reaped significant benefits for many plants, but an estimated half of all control in North America is still pneumatic.

Products that accommodate standard protocols are just beginning to enter the market. The infrastructure is in place to achieve savings, integrate functions, further efficiency, and link to information technology systems. How fast it is optimized depends in large part on you.

Plant Engineering magazine acknowledges with appreciation the special contributions made to this article by the following companies: Echelon Corp., Palo Alto, CA; Herman Bogot & Co., Park Ridge, IL; Honeywell, Inc., Minneapolis, MN; Landis & Staefa, Inc., Buffalo Grove, IL; and The Trane Company's Building Automation Systems Div., St. Paul, MN.

A special thank you to Automated Logic Corp., Kennesaw, GA, for providing the cover photo, which shows a facility controlled by a centralized BAS.

Key concepts

Greater efficiency and savings in building automation systems (BASs) are achieved if plant engineers take time to audit facility performance, establish data collection mechanisms, and analyze reports.

A variety of issues -- including interoperability and the year 2000 problem -- are making this a time of transition for BASs.

BASs help plants meet business objectives, but more progress must be made before products and standards evolve to the point where systems can be optimally applied.

Moving beyond scheduling and monitoring

Certain factors are critical to any attempt to optimize a BAS as a business tool. Consider these five principles when evaluating efforts to improve existing performance or when analyzing a proposed new system.

1 Gather data. It is rarely possible to have too much. Reliable data provide the backbone for analyses and problem-solving activities. Do not rely on data alone; however, but take a system-wide approach to performance analysis and problem/solution optimization.

2 Rely on standard, easy-to-understand applications. Ineffective scheduling or poor alarm management resulting from complex configurations is a waste of time and effort.

3 Consider specialized applications -- even those considered unfeasible a few years ago.

For example, good ventilation control applications form the foundation for good indoor air quality (IAQ). If they are a part of another plant system, provide a standard and flexible way to link them together.

4 Make use of local support and advice. Maintenance and service contracts are becoming increasingly valuable tools. BASs can and should be continually fine-tuned to meet a facility's changing needs.

5 Develop a systematic plan for optimizing energy use.





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