Most process plants have a need for some type of facilities management and corresponding building automation systems. The degree of sophistication ranges from very simple for a plant with mostly outdoor equipment, such as a petrochemical facility, to quite complex for pharmaceutical and other plants where climate control and air quality are integral parts of the process.
These degrees of sophistication, along with other factors, drive the decision to use one system or two for process control and building automation. Other key factors include upfront costs, operating expenses and staffing requirements.
Sometimes there's no choice. Paul Darnbrough, engineering manager at system integrator KDC Systems in Los Alamitos, California, explains, "Most places we go already have an embedded building automation vendor, and future work almost always goes to that product line. For larger projects we typically are involved with, the specifying engineer seems to drive the choice of using a single, common system or multiple independent systems for manufacturing and facility automation."
But if there's a choice, some plants find a unified system to be the preferred solution for their specific applications.
One System Is Simpler
End users are looking hard at single-source solutions, and in all cases, it's a process automation system controlling both the process and the facility. Building automation systems simply aren't capable of controlling anything but the simplest processes, and thus, aren't used as a single system for both process and building automation.
"I've been involved with co-gen power plants where they had four different systems, including their chilled water system, all on separate control systems with their own HMIs," says John Boyd, technology leader at Maverick Technologies, a systems integrator in Columbia, Illinois. "We finished one plant project about two years ago where everything was integrated into a single control system. It may actually have separate processors, but it's all with one supplier, and it looks like one system to the operators."
All plant subsystems should be integrated into one overall monitoring and control solution, says Dennis Runo, president of Custom Automation, a system integrator in Mesa, Arizona. "Successful plant processing is inextricably linked to the supporting building facilities. With two separate systems, information can be made to bridge the gap, but it's much easier when you have a unified system."
One reason is to reduce operator confusion. "A well-executed system will have predictable equipment control and alarm behaviors," he notes. "Pop-up information, alarm and control windows will be consistent across all equipment and subsystems. Many HMIs have templates to make this easier. Multiple systems could theoretically achieve this as well, but think of the added work and expense to get them there and keep them synced."
The U.S. Dept. of Energy's Waste Isolation Pilot Plant (WIPP) in the Chihuahauan Desert of southeastern New Mexico, some 26 miles east of Carlsbad, processes radioactive waste and safely entombs it in deep underground chambers (Figure 1). Thirteen critical subsystems are managed in the control room on a single system that handles everything including ventilation, electrical distribution and energy monitoring, HVAC, fire protection, radiation monitoring and plant protection (Figure 2).
The WIPP site uses redundant KEPServerEX servers with OPC and OPC UA to communicate with numerous subsystems using BACnet and other protocols. The interconnected subsystems talk to each other and accept commands from the operators on duty. The system is also designed to act independently to maintain a safe environment.
Reasons for choosing a single system typically involve simplicity, single-vendor responsibility, reduced maintenance costs and standardized operations.
"If the process has many different solutions in place, it can be expensive to support and maintain," says Paul Matatall, network specialist at Optimation, a system integrator in Boston. The facility will need support staff that understands how all this equipment works and how to resolve any issues that arise. It will increase their training budgets because their support teams will need to be trained on the different equipment used in their facility. They'll also have increased cost in their spare parts inventory because of the need to have many different products on hand.
Erik Dellinger, product manager at Kepware Technologies in Portland, Maine, adds, "The one-system approach affords the facility the expected benefits of minimized spare part requirements, consolidated training, integrated communications and a common look and feel."
Ripon Cogeneration (Figure 3), a power plant in Ripon, California, had multiple systems, but saw the advantage of bringing them all together, so the operators could run the system more efficiently.
"Customers ask us to integrate all the systems into one," says Boyd. "For companies looking to be more efficient, that's a positive thing. The benefit of one system is the ability to be more efficient, and that's in the context of large, enclosed plants where they have extensive HVAC and climate control units.
Those systems now are very intelligent and automated, and they have their own web portals and pages to control them. It doesn't make sense to keep them separate if you can bring them into one. I don't know any reason why you would want to keep them separate unless the operators are already so busy that they can't be distracted by the building control system."
Another advantage of a single system is simplified communications, making it easier to perform integrated control, obtain cost and operating data across the plant, send data to a historian and allow building controls to handle load changes smoothly and efficiently.
But it isn't all rosy in single-system land. Dellinger points out, "If it's all in one system, and that system goes down, you lose control of manufacturing and the building. If an operator on the manufacturing floor logs in and accidentally turns off the HVAC, that could be a problem."
Another drawback arises during system upgrades. "Obsolescence is a big reason against consolidating process automation, building automation and utilities," says Kelli Malloy, leader of U.S. process automation at Turck. "While many DCS companies have obsolescence plans and product support, the reality is that one day these products will need replacing. In addition to the cost of replacing an entire system, there are other disadvantages to forced migrations when everything is on a single system. These include extensive reprogramming and possible operational disruption, as well as the potential for point-by-point revalidation on particularly sensitive DCS changes."
Another reason for separates is that building automation suppliers understand climate control much better than process control vendors, making several companies lean toward the two-system approach.
Separation Can Be Sensible
Can standard process control equipment and systems handle building automation? Yes, but Darnbrough points to a harsh reality about using them for that: "Building automation systems offer preconfigured features specific to HVAC and other extended capabilities, such as calendar scheduling, that make sense for the application. These same options might need to be manually created and coded into a PLC or DCS system at great effort. We rarely use PLC controls for building automation." Furthermore, building automation systems are much cheaper than process automation systems—often less than half the price.
Matrix Technologies, a system integrator in Maumee, Ohio, prefers using two systems for process control and building automation. Charles Sheets, director of the industrial systems division at Matrix, says, "Since standard automation components can perform many functions, the same hardware and software can be used to control many different devices including HVAC, boilers, security access, compressors, water, etc."
Sheets adds that the physical separation is beneficial for maintenance, security and to ensure that a problem with one system won't affect the other. But he wants to use the same components. "Using standard automation components such as PLCs allows one service organization to support both systems for troubleshooting and spare parts."
Support problems often come up with existing plants that have older controls. "One of our projects involved an industrial power plant where the original HVAC controls had been subcontracted to a third party," Sheets explains. "Technical support was very difficult to obtain for their proprietary systems. Some of their equipment used PLCs, and those could be readily supported. The systems with proprietary hardware could not." Using the same controls—but in separate systems—eliminates the problem.
"Another project of ours involved optimizing energy recovery from both HVAC and process equipment for a major food manufacturer. In this case, both systems use PLC controls developed by Matrix Technologies. Since the two systems communicate, we orchestrated a strategy based on real-time process and HVAC conditions to optimize overall plant performance, resulting in significant savings."
Control and security issues are different between process and building automation. "For example, if third-party monitoring of fire, emergency and security is needed, then it might be better to use a full-service building controls organization," Sheets says.
There's also some value in dealing with experts in the field. "Proprietary building control systems virtually eliminate unauthorized access," Sheets notes.
"Building control companies typically have established knowledge of environmental and other control equipment, and often use a pricing model of lower initial costs with guarantees of a long-term service/monitoring contract. Depending on cash flow, this could be a benefit."
Process control vendors and equipment can perform building automation, too, but maybe not as well. "Often, the intellectual property of building control vendors is concealed as part of their offering. It's just part of the magic. But there aren't any building automation functions which can't be readily handled by process automation HMIs, PLCs and sensors," Sheets says. "The challenge is in having the application knowledge to implement the functions."
Using one system also might put a strain on building automation vendors. "Building automation system vendors typically have a standard hardware and software solution and would have to modify their controls to support process industry equipment and standards," says Optimation's Matatall. "Having them change their technology to the process standard might raise the cost of their equipment, and even eliminate them from bidding a project completely."
The need for environmental control varies across the process industry. "Even within a particular facility, building management requirements differ based on the type of space. Regulated industries, such as life sciences, must report on conditions that could impact production, including humidity and temperature. These applications require industrial-grade, precise measurement and control," says Bob Lenich, global Syncade business director at Emerson Process Management. "In these same facilities, gray spaces, such as offices and corridors, have less stringent reporting requirements, in which case, commercial-grade instrumentation and controls may be more appropriate and less expensive. For these spaces, a building management system makes sense.
"There's growing interest in understanding how building environments affect production in the food and beverage and specialty chemicals industries. The two-system approach is an effective one for them as well. They get the benefits of best-in-class technology for both process control and building management without the expense of a single, combined system."
Every industry segment has its own requirements for process control and building automation, says Malloy. "In some cases, such as with small chemical manufacturers, light industry or non-GMP processes, one system could potentially do it all. However, for large processing facilities in biotech, pharmaceutical and semiconductor, where building automation plays a role in the quality of the end product, multiple levels of control systems are standard and for very good reasons."
Choosing between a single or multiple systems isn't an easy choice. "Conceivably, with the right servers and processes in place, all manufacturing and building automation data could be tracked by one system and integrated in one place," says Malloy. "However, for most industries, this isn't possible or not a good idea."
For example, pharmaceutical manufacturer Bayer HealthCare, Berkeley, California, keeps its process and building automation systems separate. The company has several operational areas, and most use a combination of control platforms. At the Berkeley site, it uses ABB DCS controllers for process automation with a combination of Rockwell Automation and Siemens PLCs, plus a few proprietary systems for specialty processes. With the DCS, the plant has the redundancy and control capability a major pharmaceutical facility needs. The PLCs give it the flexibility to add small systems when needed.
"Getting the MES and building automation system to communicate all information with the DCS is a large and complicated undertaking, and gets more complicated when the data is then fed to a historian. But having the systems run separately gives flexibility to the control system that's beneficial to revalidation," notes Chris Williams, associate director, API engineering at Bayer.
"It's not that we don't see the advantages of using a single control system; it's that the disadvantages for our different process areas are costly. One of the larger operating costs we have is software and tag licensing. We can save some significant costs by keeping non-GMP processes off our DCS and operating on a lower-cost-of-ownership SCADA. However, the primary expense regards replacing equipment in a validated process. Using equipment that can communicate over multiple processors is one thing that interests us, and having partners with that kind of equipment to make validations easier is advantageous to us."
On the other hand, the ability to integrate multiple control platforms and islands of control in a plant is becoming easier and more commonplace, says Malloy. "It will become even more feasible in the future for multiple controllers to talk over open protocols and integrate over non-proprietary boundaries. This will minimize the risk of how controllers communicate, how resources are allocated along operational unit lines, and how to mitigate obsolescence of technology."
One system can work well for companies that are dedicated and vigilant about maintaining the single system. One successful example is a large food manufacturer that opted to switch to a single PLC manufacturer, a single platform and, whenever possible, a single bus protocol at its facility.
"The company has seen single-system benefits through having dedicated programmers familiar with the PLC programming language, consolidation of spare parts and the ability to train technicians on a single platform for troubleshooting purposes," says Malloy. "There are challenges, but the company is committed to the success of this single system. Management is made easier because the manufacturer does not require revalidation. One potential problem for manufacturers considering this switch is heavy reliance on one vendor for technical support."
Even when systems are separate, they can be presented to the operator as one. Boyd explains. "A Quaker-Muller yogurt plant we completed in Batavia, New York, was originally designed and built with two separate systems, but they asked us if there was a way to integrate the two, so that the HMI screens and parameters on the HVAC system could be integrated into the process automation system. At Quaker-Muller, the climate control system is very important and really integral to the process itself, and we were able to fulfill their request."
In either case, companies are interested in how long they'll be able to operate before the equipment is obsolete. Proprietary controllers increase the risk of obsolescence, while non-proprietary controls open opportunities for companies to gain functionality while minimizing reliance on a single manufacturer.
"Can We Talk?
One problem with a two-system approach is that building automation systems have adopted BACnet communications, while process control systems use fieldbus and Ethernet networks, such as EtherNet/IP and Profinet. Can the two talk to each other?
"Companies like ProSoft Technologies make cards that talk to the majority of building automation systems," says Maverick's Boyd. "We used the cards to integrate the HVAC systems at a Sun Chemical plant into the main control system."
Boyd believes ProSoft would not have designed and manufactured a series of products designed to interface with building control systems if no demand for that capability existed.
Sheets agrees. "We're seeing two trends—a movement of the building automation system manufacturers to use more standard protocols, such as the Internet of Things, and more tools to integrate them."
Dellinger adds, "There's no ideal solution here, but a good one we routinely see is two separate systems that only share the data they need. For example, PLCs and software on the manufacturing floor might be communicating via EtherNet/IP, and the building system might be using BACnet. These are two different systems, but an OPC server can communicate both BACnet and Ethernet/IP, and provide access and translation of only the data needed between systems.
"Today, it's less common to see manufacturing and building automation tied together into a single system. As for the future, we'll see—but I would bet we move more toward consolidation."
There certainly is a trend toward consolidating process control and building automation systems, especially in new plants. This consolidation can range from using one system to control everything to using two systems with tight integration via digital data networks.
In older plants, a building automation system probably already exists, may be doing its job very well, and justifying its replacement may be difficult. Instead, an existing building system can be easily integrated into a new process control system with tools like BACnet interface cards, OPC and Ethernet.
In newer plants, either approach will work, with selection of a combined process and building automation system or separates driven by the application requirements.