Central Plants Optimization and O&M

Energy efficiency, lower life-cycle-costs, reduced chiller capacity requirement and promoting greater comfort, health and productivity for occupants are all driving factors for centralizing cooling equipment in multi-building campuses. However, these benefits are not realized unless these plants are commissioned correctly, operated efficiently, maintained appropriately and their performance is being continuously monitored, verified and maintained.

Chiller plants produce chilled water and transport it to buildings through a campus wide piping system. A typical chiller plant operating efficiency should be in the range of 0.5-0.75kW/ton. The majority of central cooling plants today do not operate within these efficiencies. In fact, it is estimated that majority of water-cooled, centrifugal, central plants operate in the range of 1.0-1.2 kW per ton or in the “require improvement” range. Problems ranging from low delta-T, higher than needed pump pressure, load changes, and lower equipment performance all lead to lower performance.

Optimization of chilled water flow and proper maintenance of the plant can significantly improve energy efficiency and offer significant operating and maintenance cost savings. This can be accomplished while also improving and enhancing the comfort of the occupants.

The optimization process begins with identifying existing conditions, measuring existing systems efficiencies and parameters like supply/return temperature of chilled water, flow, temperature of condensing water, peak operating efficiency of the chillers and understanding the sequences of operation of the existing central plant. Once the existing system operation, efficiency and parameters are determined, modifications to existing sequences of operation and parameters are studied and undertaken to ensure efficient operation of the plant. The plant is then programmed to run automatically to ensure equipment operation at its peak efficiency based on its run history and efficiency profile and pumps and cooling tower fans running at the right speeds.

Maintenance of the plant also plays a key role in the efficient operation of a chiller plant. Maintenance identifies the issues before they become a problem that disrupts the operation keeps plants operating efficiently. Once the central cooling plant operation is optimized, it is important to ensure the efficiency levels are being maintained over the plant’s entire life-cycle to realize lower operating and maintenance costs. This is done by measuring the performance data on a regular basis, and verifying and managing the same as part of an on-going commissioning process.