Objective/ Method/Outcome
Objective: Determines if the Economizer Damper is open while mechanical heating or cooling are active.
Method: Compares the Economizer Damper to the Heating Coil and Cooling Coil operation. If the Economizer Damper is open while the Heating Coil Valve or Cooling Coil Valve are open, the hours of faulty operation are calculated. Avoidable Cost and Potential Savings are calculated based on the Electricity Rate and Natural Gas Rate.
Outcome: This rule generates an insight if the Weekly Hours of Faulty Operation exceeds the acceptable weekly threshold.
Description
ASHRAE36-5.16.14.3
This rule is applicable for system with separated minimum outdoor air damper and economizer outdoor air damper. Economizer damper shall close and minimum damper shall open in mechanical cooling and heating mode. Too much outdoor air intake will result in excess thermal energy consumption
This rule is part of the CopperTree Standard rule-set. (Aliased Celsius)
Default Priority
Medium
Diagnosis
1. Input sensor(s) faulty or miscalibration. Verify input sensor(s) operation.
2. Check AHU control logic, ensure economizer damper is locked in mechanical cooling or heating mode.
Message
Economizer damper is opening in mechanical cooling or heating mode. Too much outdoor air intake will result in excess thermal energy consumption.
Rule Template
Insight Type: Fault Detection
Trigger Type: Active High
Notes
1. This rule may be invalid if COVID ventilation strategies are in effect.
2. Expected values for “SF Status” inputs are “0” or “1”.
3. Expected values for “Supply Fan Speed” inputs are “100” if they are constant speed fans or not available.
Default Values:
Const. – OAT Dead-band [°C]:1
Const. – Acceptable Hours per Week [hrs]: 8
Const. – Economizer Damper Threshold [%]: 5
Const. – AHU Rated CFM: 10000
Const. – Electricity Rate($/kWh):0.1
Const. – Natural Gas Rate ($/mmBTU): 3
Const. – Weeks of Operation: 52
CTLs:
Economizer damper open with mechanical cooling or heating – Weekly Hours of Faulty Operation (KPI)
Economizer damper open with mechanical cooling or heating – Hours of Faulty Operation (CUSUM)
Economizer damper open with mechanical cooling or heating – Avoidable Cost [$]
Economizer damper open with mechanical cooling or heating – Potential Savings [$/year]
