A multi-storey corporate campus struggled with rising utility bills and frequent comfort complaints. After upgrading its AHU/PHU exhaust-air loop with a dual-CPU Symbiotic Automation control solution, the facilities team trimmed HVAC energy by one-fifth while maintaining uninterrupted air quality compliance.

Challenges Faced

• Separate AHUs and PHUs ran on fixed schedules, wasting fan power during low occupancy.
• Temperature and CO₂ drifts went unseen until occupants raised tickets.
• Any controller failure risked downtime penalties and data-centre hot spots.

Implementation

Two hot-standby PLCs now modulate dampers, VFD fans, and exhaust valves in real time. PID loops adjust airflow from live temperature and CO₂ sensors, while a building-wide HMI logs BACnet points, pushes alarms, and lets operators fine-tune set-points remotely.

Key Implementations

• Dual-CPU, zero-switchover PLC architecture for continuous operation
• CO₂-based demand-controlled ventilation reducing over-ventilation losses
• Unified HMI dashboards showing KPIs, trends, and alarm history
• BACnet historian archiving temperature, pressure, and energy metrics for audits
• VFD integration synchronising supply and exhaust fans to exact load

Outcomes & Benefits

• 20 % energy reduction in fan and reheating loads within three months
• 0 unplanned downtime since commissioning, protecting tenant SLA commitments
• 30 % tighter CO₂ control, enhancing occupant wellbeing and regulatory compliance

Future Scope

With reliable data streaming, the campus can layer cloud analytics to benchmark building performance, schedule condition-based maintenance, and automatically optimise set-points based on occupancy forecasts.