Diagnostic Priorities
Diagnostics for each analysis on equipment produce priorities for Energy, Comfort, and Maintenance based on the severity of identified issues. The priorities are measured on a scale of 0 (no priority) to 10 (highest priority) and reflect the most severe possible root causes of the issue(s) found. In cases where multiple issues are identified within a single Diagnostic, the maximum priority is used for Maintenance and Comfort, while the priorities are summed for Energy, resulting in a single priority for all the issues.
Energy Priority
Energy Priorities are determined based on the total avoidable cost determined by the Diagnostic result for each analysis on equipment. To understand how the Energy Priority is calculated, let’s first define the AnnualCostThreshold and AnnualCostThresholdZone variables.
Annual Cost Threshold and Annual Cost Threshold Zone
The AnnualCostThreshold is a value set by the customer to indicate their annual “pain point” cost. By default, it is set to 10,000 in local currency (e.g., $10,000 in the United States) for all equipment except zone equipment. Zone equipment has a separate variable, AnnualCostThresholdZone, with a default of 3,650 local currency. These are typically assigned as building variables (BVARs), but it can be changed for different pieces of equipment by assigning equipment variables (EVARs). The AnnualCostThreshold and AnnualCostThresholdZone define two important aspects:
The annual energy cost savings at which Clockworks assigns an Energy Priority of 10 on the equipment analysis.
The lower limit energy cost savings below which costs are not displayed, even if they are calculated. This lower limit is equivalent to when Energy Priority < 1. For example, if the AnnualCostThreshold is $10,000, any cost calculations below the daily threshold of $3 will be shown as $0.
Energy Priority Calculation
The Energy Priority is then based on the ratio of the annualized total avoidable cost, assuming the issue will persist for the entire year, to the AvoidableCostThreshold. Here is an example to illustrate the calculation:
If the monthly diagnostic results in an avoidable cost of $400, the annualized total avoidable cost would be 12 * $400 = $4,800.
Assuming the AnnualCostThreshold is the default of $10,000, the Energy Priority would be $4,800 / $10,000 * 10 = 5.
There are two circumstances when an Energy Priority cannot be calculated from the avoidable cost and instead a low priority (1 or 2) is assigned per issue.
Information is missing from the asset so the avoidable cost cannot be calculated. The diagnostic notes will list the equipment variables or point types the equipment is missing.
Additional instrumentation is required beyond what is provided by the BAS to calculate the energy savings or not enough data is available from required points for the energy calculation.
Comfort Priority
Comfort Priorities are assigned when an issue is identified that directly or indirectly affects human comfort. In general, a Comfort Priority is assigned when there is a deviation from the desired setpoint in temperature, flow, pressure, CO2 concentration, or relative humidity. The value of the Comfort Priority is directly proportional to the distance of the value from the setpoint (deadband) and the duration of the setpoint issue.
Deadbands and Fault Duration Thresholds
Both deadbands and fault duration thresholds are configurable equipment variables (EVARs), but the following default values are used:
Plant temperature deadbands = 8 °F (~4.4 °C).
Zone temperature deadbands = 6 °F (~3.3 °C)
All other deadbands = 20% of setpoint value (10% off on either side)
All fault duration thresholds = 150 minutes
Maintenance Priority
Maintenance Priorities are assigned when an issue is detected indicating the equipment is not operating as expected. The Maintenance Priority is determined based on the severity of the issue and its total duration. This calculation ensures that issues occurring over a longer duration will have a higher Maintenance Priority compared to the same issue occurring over a shorter duration.
Maintenance priorities are not assigned for Opportunity or Capital Project results.
General Rules Governing Maximum Priority Values
Maintenance Priorities range from 0 (no maintenance issues) to a maximum priority that is determined based on the following rules:
Plant equipment issues have a higher maximum priority than similar zone equipment issues.
Issues indicating broken equipment have a higher maximum priority than inefficient operation.
Example: A fan not turning on when it is supposed to has a higher maximum Maintenance Priority than a fan which is running when it should be off.
The highest Maintenance Priorities (9-10) are reserved for potentially dangerous or damaging problems.
Example: A boiler with near 0% oxygen content in its flue gases is assigned a maximum Maintenance Priority of 9 because of concerns about CO generation.
Common Examples of Maximum Maintenance Priorities for Specific Issues
Maximum Priority of 2: Sensor problems or insufficient economizing
Maximum Priority of 4: Manual overrides, stuck valves or dampers, short cycling
Maximum Priority of 6: Leaking values or simultaneous heating or cooling
Maximum Priority of 8: Boilers or chillers not running when supposed to or negative pressure issues for air-side systems
Maximum Priority of 9-10: Low boiler flue gas oxygen content or chiller is on, but isolation valves are closed