Chiller Plant Optimisation System (CPOS)

Overview

The control optimisation system manages the operation of water-cooled centrifugal and air-cooled chilled water plants. It holistically optimises performance by monitoring and controlling five interdependent subsystems: cooling towers, condenser pumps, chillers, chilled water pumps, and air-handling units.

The system is customised to fit the unique design of each chiller plant and its associated building loads. It maintains optimal differential pressure across the system, manages chiller lift by addressing flow issues under part-load conditions, and increases deliverable tonnage.

Although it does not require expensive variable frequency drives (VFDs) for chiller compressor motors, the control strategy does require VFDs for all ancillary components—including primary and secondary chilled water pumps, condenser water pumps, and cooling tower fan motors—to achieve optimal part-load efficiency. In some cases, additional piping and valve modifications (e.g., converting from 3-way to 2-way) may be needed, depending on the existing system’s age and design.

The system is chiller-brand agnostic and compatible with most building automation systems (BAS) that use BACnet or Modbus TCP/IP. It can be installed as a retrofit without voiding equipment warranties, and is equally suited for major renovations or new construction projects.

A typical System Architecture of Chiller Control Optimisation System

Frequently Asked Questions

What efficiency gain does chiller plant optimisation typically deliver?

System-level kW per refrigeration tonne (kW/RT) typically improves by 10 to 25 percent after optimisation, depending on existing controls maturity and plant configuration. The largest single contributor is correctly staging chillers and decoupling primary and secondary loop flows to maintain optimal differential pressure.

Do I need to replace my existing chillers?

No. Optimisation is achieved through controls and sensors layered onto the existing mechanical plant. VFDs on ancillary equipment (pumps, cooling tower fans) are usually required even where chiller compressors remain fixed-speed.

How long does commissioning take?

Typical mid-size commercial plants (500 to 2,000 RT) commission in 6 to 12 weeks, including baseline measurement, control logic deployment, performance verification under varying load, and operator training.

Does the system handle part-load conditions?

Yes. The control strategy addresses chiller lift, flow imbalance, and cooling tower fan staging under part-load (often the dominant operating condition for non-data-centre buildings). Performance gains under part-load typically exceed gains under design-day full-load.