Get Your (Alarm) Priorities Straight!

Proper assignment of alarm priority helps FM operators stay on top of critical events, mitigate risk, and prevent unplanned downtime

6 min readAug 14, 2023

What You Should Know:

The priority of an alarm is meant to convey its relative importance versus other active alarms. Accurate prioritization guides the FM operator / dispatcher about which alarm to respond to first in order to prevent the worst potential consequence (business impact).

Why it Matters:

Incorrect alarm priority can lead to the following:

Too many high priority alarms — If all alarms are critical, then no alarms are critical”.
Inability to triage alarms and events in real-time — to always be responding to what is most important in the present moment.
Missing of critical alarms — If critical alarms do not stand out (because of their higher priority) they are much more likely to be missed.
Poor Risk Management / Mitigation — when priority is assigned based on the potential business impact and time to impact, it becomes a proxy for operational risk.

Loss of experienced personnel and institutional knowledge exacerbates this situation. New BAS operators are more likely to struggle in their role if they cannot rely on alarm priority to guide response. Effective alarm prioritization compensates for a lack of facility experience and knowledge.

How to Tell Whether Your Alarm Prioritization is Effective

To evaluate the effectiveness of your alarm prioritization, conduct the following test:

1. Pick any two alarms in your system. Don’t look at their current priority.

2. Consider which one of the two is more important by answering the following question:

If you could respond to only one of the two alarms, which one would it be?

This forces you to determine which alarm has the greater potential business impact if not responded to (based on how your institution evaluates risk).

3. Next compare their current priorities. The alarm selected for response should have a higher priority (indicating it should be responded to first).

4. Repeat for other sets of alarms.

If you find many examples where the more important alarm does not have the higher priority, then your prioritization is not effective.

If only one alarm was ever active at a time, then alarm priority wouldn’t matter. Since this is rarely the case, ineffective prioritization creates a problem for an operator. They need to be able to rely on priority to drive their order of response and understanding of importance. An incident that occurs because an operator failed to respond to a critical alarm that was not appropriately prioritized (and not identified as critical), is a failure of the system not the person…

What Should Alarm Priority be Based On?

In a previous post the following definition was proposed for a facility alarm:

Facility alarm:

a facility abnormal space condition, performance deviation, or equipment malfunction…
which requires a timely operator action… (e.g., write a work order that is dispatched through a CMMS, adjust a room temperature setpoint through the BAS)
to prevent a consequence. (e.g., loss of research specimens in an environmentally-controlled lab).

Since the alarm definition stresses the need for a timely operator action to prevent a consequence, it is logical that alarm priority would incorporate these two factors (time for operator action and consequence severity).

This is consistent with definition of alarm priority used in other industries, such as process:

Priority: “the relative importance assigned to an alarm within the alarm system to indicate the urgency of response (e.g., seriousness of consequences and allowable response time)” — ANSI/ISA-18.2–2016.

The Relationship between Priority and Risk Management

An effective alarm system can help mitigate risk of facility events that cause lost revenue, equipment damage, occupant impact, etc. For the alarm system to support risk mitigation requires that alarms be prioritized based on potential business impact (the severity of the consequences).

The American Society for Health Care Risk Management (ASHRM) defines risk as follows:

Risk = Likelihood x Impact x Velocity (Optional)

Likelihood — the number of times an adverse event or occurrence will happen (frequency or probability)
Impact — the anticipated outcome, typically expressed in $$ or harm to people (severity or consequence)
Velocity — the speed of an event occurring, the time in which you have to take action (time to impact)

Since alarm priority represents the relative importance of alarms that have already occurred, the likelihood of occurrence is not a factor:

Risk (Alarm) = Consequence of Impact x Time to Impact

This is consistent with the definition of alarm priority above.

Example — Sanity Check

Failure of Two Air Handling Units causes loss of conditioned air to the spaces they serve.

Example: Alarm Priority for Air Handling Unit Failures

Important Takeways:

Alarm priority is not set based on the type of equipment that has failed (both failures are to Air Handlers), but instead reflects the significance of the potential consequences to the spaces they serve (loss of research vs. minor damage to contents in storage)
Alarm priority represents the significance of what COULD happen (the consequence that can be prevented), not what HAS happened. An alarm that indicates the “Chiller has shutdown” is not as important as the one that says “the Chiller will shut down if you don’t take action now”.

More Priorities must be Better (and Other Common Mistakes)

Since alarm priority is set in your building automation system (BAS), which typically gets added to over time and updated by different vendors and integrators, it is no wonder that prioritization can be inconsistent and inaccurate. Common resulting issues include:

Alarm priority is not used (not configured)
Alarm priority is left at the BAS default values (not set based on potential consequences)
There is no documentation or explanation of how alarm priority has been set (rationale)
Alarm priority is used to represent the area / system from which the alarm originates (e.g., Chiller Plant) or indicates the role that is responsible to respond (HVAC Shop)
More than four different alarm priorities are used
Too many alarms are critical (highest / high priority)

Selected Best Practices

Do not use more than three to four different alarm priorities in a system (e.g., “Highest”, “High”, ”Medium”, “Low”). Based on years of human factors studies we know that relative importance becomes unclear when there are too many different priority levels.
To keep “High” priority meaningful, only a small fraction of alarms (say 5–10%) should be assigned to this level. If 50% of your alarms are “High” priority the operator doesn’t know which one to respond to first, so they will ignore priority altogether.
Alarm displays should support sorting / filtering to keep High priority alarms in front of the operator. This will help operators stay focused on what’s important during upset situations (e.g., power loss).

Call to Action:

Virtual Facility’s Alarm Triage overlays your existing BAS’s to create a common view of alarms. By centralizing alarms from all of your different systems into a single view, a common alarm prioritization schema can be applied. Thus, it does not matter whether your alarms are prioritized from “0” to “255” (Johnson Metasys) or “Level 1” to “Level 6” (Siemens Apogee), they can be “normalized” within Alarm Triage to follow a standard prioritization and message formatting.

If you want to improve operator response, set alarm priority so it accurately reflects criticality… We can help. Contact us to learn more.

Email us: makebetterwork@vfacility.ai

Web: www.virtualfacility.ai