Building Automation
Since a building automation system’s key features include dynamic adjustment to a building’s requirements, there are edge cases of operation that can hardly be planned for. As they become aware of them, the DDC application engineer can learn from them and apply the learnings to the next job. I did have the pleasure of sharing with my colleague a recent edge case that had him stumped as to how to plan for. The project required monitoring of a supply air detector’s auxiliary contact on a 100% outside air unit. During commissioning efforts, the chilled water valve for the unit was indexed to 0%, 50%, and 100% open while the unit was running. This was on a hot summer day in North Carolina, and the sudden burst of moisture was introduced when the chilled water valve was closed, which tripped the supply air duct detector. When the smoke detector tripped, the unit shut off, and it took some methodical adjustment to get enough air movement around the duct detector to clear the alarm condition. For some background on this, the chilled water valve actuator was wired to go to 100% open on a loss of power, and the unit is designed to run 24/7. So, this particular condition is hardly one to plan for.
For career growth, it’s important to keep doing things you’ve never done before, and my colleagues shared some stories about this. Demand control ventilation (DCV) is a somewhat nuanced control strategy that deals with tuning the amount of outdoor air intake based on the carbon dioxide sensed in a space that has highly variable occupancy. Classic examples of this are conference rooms, classrooms, and auditoriums. The typical “levers to pull” are things like dampers on an outdoor air intake, fan speeds, and others. However, my colleague once had the challenge of designing a control strategy for an indoor basketball stadium for a major Division I NCAA team. Instead of designing a control strategy that turns up and down for tens or a couple of hundred people, this system had to turn up and down for thousands. In the end, his control strategy involved accomplishing turn up and turn down with redundant air-handling equipment that rotated for runtime equalization to keep all in good working order.
With the advent of more advanced sequences of operation, such as those introduced in ASHRAE GPC 36, the requirement for sensors and dynamically adjusting systems just grows and grows. Add to the mix a newfound focus on IAQ available with new and old air-purification techniques and increased ventilation standards. And, then, on yet another front, we are seeing the cross-pollination of IoT best practices, machine learning, artificial intelligence, and an enhanced occupant experience. To keep up, a DDC application engineer has a brave new world of topics to explore and become familiarized with, as they intuit what an owner really needs and delivers a design for the solution.