THE HIDDEN COST OF HVAC INEFFICIENCIES: HOW FDD CAN PREVENT COSTLY MISTAKES (PART 1)

In large commercial buildings, HVAC systems are critical for maintaining indoor comfort and air quality. However, their complexity can make them prone to inefficiencies that, when left unchecked, can result in significant energy wastage and costs. One common example is the failure of an economiser outside air (OA) damper on a chilled water air handling unit (AHU). If the damper gets stuck fully open, the consequences are not just higher energy bills but also increased carbon emissions. This blog will explore the real-world impact of such a fault and demonstrate how Asset Assess’ Fault Detection and Diagnostics (FDD) platform can help prevent these inefficiencies, saving both energy and money.

THE SCENARIO: AN OUTSIDE AIR DAMPER STUCK FULLY OPEN

Imagine a typical chilled water AHU with a cooling capacity of 54 kW. Under normal conditions, this system should be able to regulate the amount of outside air entering the system through its economiser damper. In hot climates like Brisbane, Queensland, the system typically brings in only a small percentage of outside air (about 10%) to reduce the cooling load. However, if the outside air damper gets stuck fully open, 100% of the outside air enters the system—regardless of whether the outside temperature and humidity levels are ideal.

Let’s assume the following conditions:

• Outside air temperature: 35°C
• Humidity: 50%
• Total airflow rate: 3430 L/s
• Chilled water flow rate: 2.5 L/s
• Runtime: 24 hours

When the damper is stuck open, the AHU is forced to cool and dehumidify all the outside air, which significantly increases the cooling load. The estimated total energy impact over 24 hours would be 1118.4 kWh, compared to just 112.1 kWh if the system was operating correctly with only 10% outside air intake. This additional energy usage of 1006.3 kWh per day translates into substantial costs and environmental impacts.

THE COST OF IGNORING HVAC INEFFICIENCIES

The cost of electricity in Brisbane, Queensland is approximately $0.19 per kWh, meaning that the extra energy required to operate the AHU with a fully open damper for just 24 hours would cost around $191.20 AUD. This may not seem like much for one day, but the financial and environmental impacts quickly add up if the issue goes unnoticed for an extended period.

Let’s assume the damper remained stuck fully open for three months over the summer, a period of approximately 90 days. The total energy wastage over this period would be:

Energy Impact (kWh)=1006.3 kWh/day×90 days=90,567 kWh

This energy waste would result in a total additional cost of:

Cost (AUD)=90,567 kWh×0.19 $/kWh=$17,207.73

Not only is this an unnecessary cost, but the environmental impact is also significant. Based on the carbon intensity of Queensland’s electricity grid (0.81 kg CO₂ per kWh), the total CO₂ emissions from this inefficiency would be:

CO₂ Emissions (kg)=90,567 kWh×0.81 kg CO₂/kWh=73,359 kg CO

That’s more than 73 metric tonnes of CO₂ emitted over the summer due to a single fault in the system—equivalent to the emissions from driving a car over 400,000 kilometres!

HOW FDD CAN PREVENT THIS

Building managers often lack visibility into these types of HVAC system failures until they are reflected in sky-high energy bills. This is where Asset Assess’ Fault Detection and Diagnostics (FDD) platform comes into play.

Our FDD platform is designed to continuously monitor HVAC systems in real-time, using advanced algorithms to identify anomalies such as stuck dampers, sensor faults, or inefficient system performance. In this scenario, our platform would detect the following key issues:

• Abnormal outside air intake: The system would notice a deviation from the normal 10% outside air setting, identifying that the damper is not functioning correctly.
• Increased cooling load: The platform would track the increase in cooling energy required, flagging this as an anomaly.
• Energy inefficiency alarms: The platform would alert facilities teams to the increased energy consumption and potential cost impact.

With these insights, building managers could have quickly rectified the stuck damper – avoiding months of energy waste and reducing both costs and CO₂ emissions.

THE FINANCIAL IMPACT OF FDD

Had the FDD platform been in place and alerted the building management team within the first day of the fault occurring, the potential energy wastage could have been reduced to a minimum. Instead of spending $17,207.73 AUD over three months due to the inefficiency, the issue could have been fixed within a day, keeping the costs close to the normal operation range of $21.30 AUD/day (for 112.1 kWh/day).

In the long run, investing in a building analytics and FDD solution like Asset Assess’ platform provides:

• Energy savings of up to 30% by detecting and rectifying faults early.
• Reduced operational costs through more efficient use of HVAC systems.
• Lower carbon emissions, helping businesses meet sustainability goals and reduce their environmental impact.

CONCLUSION: DON’T LET HVAC FAULTS GO UNNOTICED

As this scenario illustrates, seemingly small faults like a stuck outside air damper can have massive financial and environmental consequences if left unchecked. With rising energy costs and increasing pressure to reduce carbon footprints, it’s more important than ever to ensure HVAC systems are running efficiently. Asset Assess’ FDD platform offers a proactive solution, providing real-time monitoring, fault detection, and actionable insights to keep your building’s HVAC system operating at peak efficiency.

By preventing faults before they escalate, you can save thousands in energy costs and reduce your building’s environmental impact – while maintaining a comfortable, healthy indoor environment for occupants. Don’t wait for the next energy bill to realise there’s a problem. Let FDD take the guesswork out of HVAC management.

Please reach out to us to find out more, and to request a demo of the Asset Assess platform here.