MAXIMISING BUILDING PERFORMANCE WITH HVAC FAULT DETECTION AND DIAGNOSTICS DURING COMMISSIONING

Commissioning a building’s HVAC system is a critical step to ensure optimal performance from the outset. Fault Detection and Diagnostics (FDD) technology is increasingly being integrated during this phase, identifying inefficiencies, misconfigurations, and potential issues. In this blog post, we explore how FDD can address specific commissioning challenges, such as valve and damper actuator misconfigurations, sensor calibration errors, and inefficient staging strategies.

THE ROLE OF FDD IN THE COMMISSIONING PROCESS

Commissioning is designed to verify that HVAC systems are installed correctly and are functioning as intended. However, even with detailed planning and installation procedures, equipment faults, and misconfigurations are common, leading to suboptimal performance. Traditional commissioning relies heavily on manual checks and balancing, which may miss critical faults that can escalate into energy inefficiencies or operational failures.

Integrating FDD from the commissioning stage offers several advantages:

• Early Fault Detection: Identifying problems like reverse-acting valve and damper actuators or incorrect sensor calibrations immediately ensures the system is functioning as designed.
• Operational Insight: FDD provides data-driven insights into how systems are operating in real-time, detecting inefficiencies such as misaligned control strategies that can result in excessive energy consumption.

EXAMPLE 1: VALVE AND DAMPER ACTUATORS REVERSING

One of the most common commissioning issues is valve or damper actuators being configured in reverse, leading to unintended operational effects. For example, a chilled water valve may open when it’s supposed to close, sending cold water through the system unnecessarily, wasting energy and impacting indoor conditions.

FDD Solution: During commissioning, FDD systems continuously monitor actuator positions and flow conditions. By comparing actual operation to expected behaviour, the system immediately flags a reverse-acting actuator. This early identification allows for corrective action before the system enters regular operation, saving energy and avoiding discomfort to occupants.

In a case study from a major commercial office building, FDD detected that multiple damper actuators were reversing during cooling demand, causing the air handling unit to underperform. Technicians were able to correct this before building occupancy began, preventing significant energy loss. (Ref. 1)

EXAMPLE 2: SENSOR CALIBRATION ISSUES

Sensors play a pivotal role in HVAC control by providing feedback to the Building Management System (BMS) regarding temperature, humidity, and airflow. However, inaccurate sensor calibrations can result in systems operating based on faulty data. For instance, a poorly calibrated temperature sensor could indicate that a space is hotter or cooler than it actually is, leading to overcooling or overheating.FDD Solution: FDD continuously cross-references sensor data with expected performance metrics and other sensor readings.

In one example, a major university found that a supply air temperature sensor was reading 2°C higher than actual, causing the HVAC system to overcool the building. The FDD system flagged this anomaly, leading to recalibration during the commissioning process, which resulted in a 10% energy savings in the first year. (Ref. 2)

EXAMPLE 3: STAGING STRATEGY INEFFICIENCIES

Staging strategies, particularly for multi-stage equipment like boilers, chillers, and air handling units, are critical for ensuring that systems operate efficiently. Inefficiencies in staging strategies often occur when equipment is brought online too early or late, leading to excessive energy consumption and equipment wear. For instance, chillers may start too soon in response to minor temperature fluctuations, using far more energy than necessary.

FDD Solution: During commissioning, FDD monitors the staging behaviour of equipment and can identify inefficient patterns. For example, in a healthcare facility, the FDD system detected that the chiller staging was not aligned with actual cooling demand, causing premature wear on the equipment and unnecessary energy use. By identifying this early on, the commissioning team could adjust the control strategies to ensure optimal staging. This change resulted in a 15% reduction in energy consumption. (Ref. 3)

LONG-TERM BENEFITS OF FDD POST-COMMISSIONING

Although the focus of this blog is on commissioning, it is important to note that FDD delivers ongoing benefits well beyond this phase. Once the building is operational, FDD continues to monitor system performance, alerting facility managers to emerging faults and inefficiencies. This ensures that the building maintains high levels of energy performance throughout its lifecycle. For example, many FDD platforms offer predictive maintenance capabilities, where faults such as degrading actuator performance or sensor drift can be detected before they cause significant operational issues. In this way, FDD not only helps correct commissioning errors but also ensures the long-term health and efficiency of the building’s systems. (Ref. 4)

CONCLUSION

HVAC FDD during commissioning is a powerful tool for ensuring systems operate efficiently and as designed from the moment they are installed. By identifying reverse-acting valve actuators, sensor calibration issues, and inefficiencies in staging strategies, FDD systems enable facility managers and commissioning teams to fine-tune performance, leading to energy savings, improved occupant comfort, and extended equipment lifespan.

As more buildings adopt smart technologies and building analytics, incorporating FDD from the start will become standard practice in the commissioning process.

By embracing FDD during the commissioning process, building owners can ensure that their HVAC systems deliver maximum performance from day one, contributing to long-term sustainability and operational efficiency goals.