This page is an extract from an internal presentation by courtesy of Leicester City Council. These figures refer to savings made on pool circulation only, there is also potential for further savings on air handling costs
The benefits of fitting Variable Speed Drive controls to electric motors have been well established for many years. It is also well known that many installed motors are actually oversized for the job that they perform. This means that a fairly modest decrease in motor speed will produce a relatively large reduction in energy consumption, under what is known as the "Cube Law." In other words, reducing the speed of an electric pump motor by just 20% can provide energy savings in the order of 50%. There is no measurable deterioration of the quality of the pool water, even though the flow rate is now slightly lower. Significant environmental savings are also expected in the form of lower atmospheric emissions from burning fossil fuels to produce electricity. In addition, VSD controls give other benefits in terms of reducing the mechanical load on the motor, which extends its useful lifetime and cuts the amount of maintenance required.