A large acute-care hospital operated by a national healthcare organization was experiencing persistent air handling unit (AHU) performance issues that went largely unnoticed through traditional building management system monitoring. As with many healthcare facilities, maintaining reliable airflow, pressure control, and indoor air quality was critical—not only for operational efficiency, but for patient safety and regulatory compliance. Using advanced building analytics, the facility gained deeper visibility into long-term system behavior, uncovering hidden performance degradation across multiple AHUs serving critical hospital spaces.
Two major AHUs serving occupied clinical areas were found to be operating at or near maximum variable frequency drive (VFD) speeds for extended periods—nearly three years in one case—without achieving required static pressure setpoints.
AHU #1 (Supply Fan Only):
The supply fan VFD was operating at 100% speed while delivering only ~50% of the required static pressure.
Historical data showed that the same unit had previously met its pressure setpoint at lower fan speeds.
Despite running at full capacity, airflow delivery to downstream zones was significantly compromised, risking under-ventilation in critical areas.
AHU #2 (Supply and Return Fans):
Both supply and return fans steadily ramped up to high VFD speeds following a reduction in static pressure setpoint.
Even at ~90% fan speeds, the unit could only deliver roughly one-third of the required static pressure.
Compared to historical performance, the AHU was no longer operating within expected design parameters.
In both cases, the systems were consuming excessive energy while failing to deliver adequate airflow—creating a dual risk of wasted operating costs and potential health and safety non-compliance.
Using continuous data analytics and engineering-driven diagnostics, the facility team was able to:
Identify long-term degradation in AHU performance that was not visible through short-term trends.
Compare current operation against historical baselines to establish achievable performance targets.
Quantify how much airflow capacity had been lost and how fan speeds could be safely reduced once underlying issues were corrected.
Prioritize corrective actions based on both energy savings and ventilation risk, ensuring patient care areas received adequate airflow.
Rather than simply accepting higher fan speeds as “normal,” the analytics provided evidence-based insight into how the AHUs should be operating under proper conditions.
By restoring AHU performance closer to historical and design expectations, the hospital identified substantial operational and financial benefits:
Energy & Cost Savings
AHU #1:
- Potential reduction of 5–20% in supply fan speed
- Annual energy savings ranging from ~56,000 to over 190,000 kWh
Estimated annual cost savings of $14,000–$49,000
AHU #2:
Optimized supply and return fan speeds
Annual energy savings exceeding 165,000 kWh
Estimated annual cost savings of $42,000+
Operational & Safety Impact
- Restored airflow capacity to ensure clinical spaces received proper ventilation.
- Reduced risk of under-ventilated zones that could affect patient comfort, infection control, and regulatory compliance.
- Improved confidence that AHUs were operating within safe, efficient, and intended performance ranges.
