CopperTree Analytics collaborated with a Canadian partner to introduce building analytics to a large federal government office building. The partner was interested in optimizing the performance of multiple affiliated buildings using Fault Detection Diagnosis (FDD).
CopperTree was engaged to work with a local controls partner to analyze a network of buildings in Winnipeg, Manitoba. The studied office building had an established Building Automation System (BAS) but never had the capability to use predictive data analytics to quantify the operating deficiencies within their building.
Upon implementing the studied building into Kaizen, we discovered faulty operation of zone Variable Air Volume (VAV) boxes. The supply
airflow of these VAVs were not meeting their desired setpoint, with sensors measuring airflow up to 6X the setpoint. This faulty operation occurred for 100% of occupied hours, with an overall average duration
of approximately 80 hours per week since data collection began.
The recommended diagnosis for this fault is to:
1. Check sensor calibration and verify operation.
2. Check if automatic control has been overridden.
3. Review and modify controller tuning parameters.
4. Verify AHU operation.
In this situation, the challenge was to determine the most relevant diagnosis for this high severity fault and then to subsequently advise measures to improve operation.
Upon further investigation of the buildings operation, we captured another fault for VAV systems resulting from dampers being open 100% for extended durations of time. From this information we were able to determine that the faults were related. With the dampers being consistently open 100%, the airflow was uncontrolled and the VAV continuously supplied air at a much greater rate than intended. The result was a recommendation to both verify damper control and verify if the damper was stuck open. From this recommendation action was taken and we observed an 80% improvement in supply airflow accuracy with respect to the desired setpoint. Additionally, occupant comfort and VAV unit energy efficiency improved.
The solution proposed by Kaizen
resulted in the following benefits to the building:
- 80% improvement in supply airflow accuracy
- Improved occupant comfort
- Increased energy efficiency of zone unit equipment.
