Determine supply air flow performance KPI score

Applicable Systems

  • Primary: AHU

Objective/Method/Outcome

  • Objective: Determine the supply air flow performance score.
  • Method: Determine the performance index of a supply air flow control system using the amount of time the supply air flow is within the deadband while unit is on.
  • Outcome: A performance KPI CTL is generated on a daily basis while there are no insights. However, a user can change the trigger block to “Insight – Bad Score”, and an insight will be generated if the weekly score is below 60%.

Logic

  • Apply the air flow setpoint input to the air flow input, and compare the deviation to a set allowed variation percentage.
  • Filter score by only passing the magnitude if occupied.
  • Extract the daily score to produce a performance KPI trend log, and extract a weekly score for the insight generation with reference to an acceptable score constant (60% by default).
  • Generate no insight unless the trigger block is “Insight – Bad Score” and weekly score is below the acceptable score.
while(occ == 1)
   {
   if( |AFLW - SP|  > 15% SP)
         {
         Award performance KPI score 0%
         }
   else
         {
         Award performance KPI score 100%
         }
   average performance KPI score daily
   average performance KPI score weekly
   }
Determine supply air flow performance KPI score

Description / Method

Determine the performance index of a supply air flow (AFLW) control system using the amount of time the airflow is within the deadband.(SP ± 15%) {VAV}

  1. Issue with control loop. Review and modify controller tuning parameters.
  2. Automatic control has been overridden. Revert equipment back to automatic control.
  3. Input sensor(s) faulty or miscalibrated. Verify input sensor(s) operation.
  4. Primary air not available. Verify Air Handling Unit operation.

Message

Variable Air Volume (VAV) air flow score is below 60% for the week. Review control loop tuning.

Notes

This rule will not generate an insight unless the user changes the Trigger Block to “Insight – Bad Score”Default Constants:

  • Const. – Air Flow Deadband [%]: 15
  • Const. – Acceptable Weekly Score [%]: 60

Output CTL:

  • AFLW Performance KPI

Rule Template Type

  • Insight Type: Integrity KPI
  • Trigger Type: Active High

Default Priority

Low

Inputs

InputsUnitsDefault ValueTagsDescription
Air FlowL/s sensor, air, flowAir flow
Air Flow SetpointL/s sp, air, flowAir flow setpoint
Occupancy  occupiedBuilding occupancy behavior
Const. – Air Flow Deadband%15 Percentage of allowed air flow variation from setpoint
Const. – Acceptable Weekly Score%60 Percentage of acceptable error

Output Calculated Trend Logs

Output CTLUnitsDescription
AFLW Performance KPI%Score representing the amount of time the supply air flow is within deadband, as a percentage
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