Determine severity of zone temperature control loop error

Applicable Systems

  • Primary: VAV

Objective/Method/Outcome

  • Objective: Determine the performance index of a room temperature control system using the amount of time and total deviation the RT is not within the desired set point.
  • Method: Analyse the performance metric based on the total time and absolute difference between the RT and the desired set point during occupied hours.
  • Outcome: A KPI score is generated on a weekly basis while a ‘Bad Score’ insight is produced when exceeding acceptable hours outside of the threshold.

Logic

  • Input normalized room temperature and the corresponding temperature set point.
  • With a temperature threshold constant, check if the deviation is out of the threshold.
  • If the threshold exceeded and the building is active, extract the associated magnitude of the temperature divergence
  • Aggregate samples into a weekly score, and generate the KPI score.
  • If the weekly score exceeds the acceptable weekly threshold, generate an insight.
while( (RT - RT_SP) > Threshold AND Occ == 1 ){
   
   Score = Score + (RT - RT_SP)
   Weekly Score Deviation = Aggregate(Score, Week)

   if( Weekly Score Deviation > Acceptable Weekly Threshold ){
      Insight- Bad Score
   }
}
Determine severity of zone temperature control loop error

Description / Method

Determine the error severity of a room temperature control system in degree centigrade-hours. {VAV|HP|FCU|UV|UH|RAD|RHT} Calculate the severity metric based on the absolute difference between the room temperature and the room temperature setpoint deadband while the room temperature is outside of the deadband and the zone is occupied.

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

Message

The room temperature has deviated by more than 4 centigrade hours in the week during occupied hours. Review controller tuning parameters.

Notes

Default Values for Constants

  • Temperature Threshold: 1
  • Acceptable Weekly Threshold: 4

Rule Template Type

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

Default Priority

Low

Inputs

InputsUnitsDefault ValueTagsDescription
Room Temperature°C/°F sensor, zone, air, tempZone air temperature records
Room Temperature Setpoint°C/°F sp, discharge, air, tempZone air temperature set point
Occ  occupiedBuilding occupancy
Const- Temperature Threshold°C/°F1 The acceptable temperature change of the unit
Const- Acceptable Weekly Threshold°C.Hr4 The acceptable weekly centigrade-hour threshold

Output Calculated Trend Logs

Output CTLUnitsDescription
RT Severity KPI°C.HrGenerated KPI score of weekly hours of irregularity
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