Cleanroom energy benchmarking data shows that chiller plant designs and operation efficiency varied a great deal in cleanroom facilities. Operating efficiency of cooling tower and condenser optimization is critical to the overall energy efficiency of the chiller plant, which has a significant impact on energy use for such facilities.sTogether with fans for delivering air to and from cleanrooms, chiller plants usually serve cleanroom facility and adjacent spaces simultaneously and use significant energy and water. Figure 1 shows benchmarked HVAC energy usages in a semiconductor cleanroom facility. In this case, the cooling towers, water pumps, and chillers account for more than half of the total HVAC energy use. Therefore, it is important to design, select, operate, and control each of the plant components to achieve high efficiency and to lower life-cycle costs for cleanrooms and their adjacent spaces.