Objective/Method/Outcome
Objective: Determines if the outdoor air damper is open when the discharge air temperature is above the setpoint and the outdoor air temperature is above the threshold.
Method: Compares the recorded supply air temperature to the sum of the setpoint and setpoint deadband to determine if it is greater when the outdoor air temperature when the damper is open. If the conditions are true, the system is at fault and the weekly hours of fault are determined.
Outcome: Triggers an insight when the Outdoor Air Damper is fully open when it is cooling, and the Outdoor Air Temperature is above the threshold.
Description
Monitors the outdoor air damper, ensuring that the OAT is low enough for 100% outdoor air to be brought in while SAT is above setpoint.
This rule is part of the CopperTree Standard ruleset and is derived from NIST APAR5 and 9.
Default Priority
Medium
Diagnosis
- Input sensor(s) faulty or miscalibration. Verify input sensor(s) operation.
- Check AHU control logic, ensure this mode is locked out when OAT is too high.
Message
Outdoor air damper is fully open while in cooling mode, while OAT is above threshold temperature. This may result in excess cooling energy consumption.
Rule Template
Insight Type: Fault Detection
Trigger Type: Active High
Logic
Inputs
| Input | Unit | Tags | Description |
|---|---|---|---|
| OAT Maximum | The set Outdoor Air Temperature maximum | ||
| SAT | ° | Discharge Air Temperature | The recorded Supply Air Temperature |
| SAT_SP | ° | Discharge Air Temperature Setpoint | The setpoint Supply Air Temperature |
| SAT SP Deadband | ° | The acceptable deviation from Supply Air Temperature setpoint | |
| Outdoor Air Damper | Outdoor Air Damper Position, Outdoor Air Damper Command | The Outdoor Air Damper Position | |
| Outdoor Air Damper Maximum | The maximum Outdoor Air Damper Position | ||
| SF Status | Discharge Air Fan Command, Discharge Air Fan Status | The recorded status of Supply Fan | |
| Threshold – Weekly Hours of Faulty Operation | hr | The minimum temperature of faulty operation that can trigger an insight | |
| OAT | Outdoor Air Temperature | The recorded Outdoor Air Temperature |
Note:
This rule may be invalid if COVID ventilation strategies are in effect.
Default Thresholds:
- Maximum OAT: 20°C 68°F
- Damper Fully Open Position: 95%
- Weekly Hours of Operation: 8
