Objective/ Method/Outcome
Objective: Determines if the VAV Airflow Setpoint changes based on heating or cooling demand or is constant.
Method: Monitors the VAV Airflow Setpoint while the zone is occupied to determine if it’s modulating between maximum and minimum values or is a constant value. If the VAV Airflow Setpoint is constant the hours of faulty operation are calculated.
Outcome: This rule generates an insight if the Daily Hours of Faulty Operation exceeds the acceptable daily threshold.
Description
Reference: ASHRAE36-5.6.5.1/5.6.5.3
This rule determines if heating or cooling output is mapped to active airflow setpoint. In most cases, active airflow setpoint should vary between minimum and maximum setpoint to satisfy heating or cooling demand. Health care facility could be an exception.
This rule is part of the CopperTree Standard rule-set. (Aliased Celsius / Aliased Fahrenheit)
Default Priority
Medium
Diagnosis
1. Review heating/cooling maximum flow setpoint
2. Review minimum flow setpoint
Message
Discharge airflow setpoint remains unchanged.
Rule Template
Insight Type: Fault Detection
Trigger Type: Active High
Notes
1. Expected values for “Occupancy” inputs are “0” or “1”.
Default Values:
Const. – Acceptable Daily Hours of Faulty Operation [hours]: 4
CTLs:
VAV Airflow Constant – Daily Hours of Faulty Operation (CUSUM)
VAV Airflow Constant – Weekly Hours of Faulty Operation (KPI)
