384

At full speed, -3% loss in inverter

Figure 27.20 illustrates the savings expected from the VSD ECM by hours of use per year. The 5% and 10% of Savings lines define the amount available for M&V expenditures at these levels. In this example, the ECM savings exceeds $253,000 per year. Five percent (5%) of savings over a 20-year project life makes $253K available for M&V and ten percent (10%) of the savings makes $506K available over the 20-year period. If the motors run less frequently than continuous, savings decrease as shown in Figure 27.20. Setting up the M&V program to monitor the VSDs on an hourly basis and report savings on a monthly report requires monitoring the VSD inverter with an EMCS to poll the data and create reports.

To provide the impact of the potential losses from losing the savings, assume the savings degrades at a loss of 10% of the total yearly savings per year. Studies have shown that control ECMs like the VSD example can expect to see 20% to 30% degradation in savings in 2 to 3 years. Figure 27.21 illustrates what happens to the

Figure 27.20: Example VSD EMC Yearly Savings/M&V Cost.

savings in 20 years with 10% of the savings spent on M&V. Note that the losses exceed the M&V cost during the first year, resulting in a net loss of almost $3,000,000 over the 20-year period. Figure 27.22 shows the savings per year with a 10% loss of savings. M&V costs remain at 10% of savings. At the end of the 20-year period, the savings drop to almost $30,000 per year out of a potential savings of over $250,000 per year.

This example shows the cumulative impact of losing savings on a year by year basis. The actual savings amounts will vary depending upon the specific factors in an ECM and can be scaled to reflect a specific application. Increasing the M&V cost to reduce the loss of savings often makes sense and must be carefully thought through.

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