HVAC Trends: Controls Conversion
By Ben H. Dorsey III
From the January/February 2014 issue of Today's Facility Manager
For decades, some building systems have benefitted from controls. Venerable pneumatic control systems use air to initialize mechanical processes. But these controls are limited to the mechanical systems such as heating, cooling, and ventilation. Newer digital control systems, commonly called building automation systems, consist of networked hardware and software capable of managing numerous building systems.
Increased energy and labor costs provide facility managers (fms) plenty of incentive to consider upgrading to more efficient systems. A partial or full conversion from a pneumatic system to a digital building automation system will provide: more actionable data for intelligent building management; lower energy costs through greater operating efficiency; lower maintenance costs through less need for calibration and service of equipment; and higher income potential through better environment control, which results in improved occupant satisfaction.
Pneumatic systems provide little or no data to the facility professional. That dearth of data means underperforming subsystems could be wasting energy, that impending breakdowns aren’t noticed until it is too late, and that maintenance is reduced to “chasing fires” instead of proactive prevention.
Digital systems, on the other hand, are all about data. These automatically adjust parameters and correct conditions that would require tedious manual labor on pneumatic systems. Digital systems also provide real-time and trended data for reports and graphs that allow for easy analysis and intelligent decision making.
Ron Tolan, facility manager of the Indiana State Museum in Indianapolis, has been enjoying the advantages of a digital automation system for a decade. “Because of the sensitivity of museum artifacts, it is important that we maintain a certain indoor environmental quality including temperature, humidity, and air quality,” he says. “With our building automation system, we can monitor and maintain the exact conditions we are looking for. The system can also alert us when pre-established safety limits are in jeopardy.”
Lower energy costs result from efficient energy usage. With a digital building automation system, fms can engage in several practices to gain these efficiencies. A sampling of such practices include: flexible scheduling, motion detection, demand control ventilation, optimum start of mechanical systems, and monitoring and optimization of system set points as conditions change.
Jody Byers is president of Automated Building Controls, a building automation contractor with offices throughout Florida. For more than 30 years the company has been designing, installing, and servicing control systems from legacy pneumatic to the latest digital systems. “Any level of control is good,” says Byers. “But digital automation can maximize the efficiency of building systems and lay the foundation for system integration that can help you realize even more efficiencies. It is not uncommon for these digital systems to be called ‘energy management systems,’ and that is just what they do.”
Pneumatic sensors and thermostats need calibration periodically to maintain reasonable accuracy. In practice, such calibration is seldom performed. Air compressors and air dryers need careful maintenance to avoid contaminating the lines with oil, and replacement costs for those items are high. On the other hand, after installation, digital systems usually provide “set and forget,” self maintaining, accurate control for long periods of time.
At the 150,000 square foot headquarters of the Royal Saudi Naval Force located in Riyadh, there was a 25 year old pneumatic control system in operation. While officials there were interested in the technological advantages of going digital, it was the high costs of maintaining their system that was the true motivation for making a change. In the words of one official there: “The knowledge and skills needed to maintain such a system were becoming as obsolete as the system itself.”
Pneumatic systems rarely complain. If something goes wrong, such as a damper getting stuck, a pneumatic system stays silent. The feedback loop is an occupant complaining that a room is too hot or too cold. Furthermore, in the time it takes occupants and fms to become alerted to issues, operational efficiencies are being lost. Thus, less comfort may also be a symptom of increased energy costs.
The real estate investment and property management firm of Live Oak-Gottesman in Austin, TX owns and manages over seven million square feet including a four story office space known as the Carillon. “We look at a lot of properties,” says Lynette Dahmer, a company vice president and director of office/retail asset services. “In evaluating potential properties, we typically ask if there is an automation system in place. This makes the property more valuable as an owner.”
Continues Dahmer, “The Carillon, on the other hand, was an older property with a mixed bag of pneumatic control. It was requiring a lot of manual operation to satisfy tenant demands, and its utility costs were twice the average of some of our other properties.”
Their energy solutions contractor, Performance Facility Services, recommended and completed an entire replacement of the aging pneumatic controls with a web-based digital control system.
“I love the convenience of operating the building from any web-based PC rather than having to go to the property to make manual changes,” says Dahmer. “We’re saving ourselves headaches and maintenance costs. And the tenants are finally getting the desired level of control and comfort that they’ve always sought.”
New commercial construction almost always has digital controls. Pneumatic to digital retrofits in existing facilities, however, require some upfront investment to garner the long-term benefits. But fms do not have to take an all-or-nothing approach. In terms of project scope, there is a spectrum of work that can be undertaken.
The most costly option initially is to rip out all the old pneumatic equipment and install new digital equivalents. This process can be time consuming, and parts of the HVAC system may need to be shut down for periods of the retrofit, creating inconvenience for the building’s occupants. This does, however, result in a highly energy efficient, pure digital system.
A less disruptive, and possibly more cost-effective, option is to replace only the parts of the particular system that make the most sense and to leave the parts that can still perform adequately in place (new “brains” to control the old “guts”). This results in a pneumatic and digital hybrid, which can still be quite efficient.
Today’s products also make it possible to install some digital intelligence on top of an otherwise complete pneumatic system. Such products at least offer some actionable data and may help lower costs as well.
Achieving an open source conversion from pneumatic to digital is feasible and desirable. As a communications protocol, air was never proprietary, and pneumatics represents the original “open system” in which one manufacturer’s device can be replaced by that of another manufacturer’s. Fms can continue this future-proofed flexibility on a digital path by selecting a vendor that provides an open protocol system. Such an open source approach provides for an fm’s choice in both products and service providers. This also provides the foundation for systems integration and data analytics solutions, thereby assuring the relevancy of the facility for years to come.
Dorsey, a 25-year veteran of technology marketing, is senior VP of marketing & communications at KMC Controls, Inc., an Indiana-based manufacturer of building automation and control solutions. To read further on digital systems, visit TFM's Building Automation Channel.
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