SIEMENS BUILDING TECH 1 -2003 - Laserfiche WebLink

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CONFIDENTIAL The results were: Scenario KWh/year A 789,019 B 559,257 __ C 833,174 D 841,780 E 270,855 F 196,755 G 293,252 H [ 297,327 From the above, we can draw several conclusions: The City of Santa Ana should immediately stop using the rotary chiller to handle their base load with a centrifugal as a backup; they should instead use the centrifugal to handle the entire load. The savings will be 841,780 kWh/year - 789,019 kWh/year = 52,761 kWh/year. Installing a VSD on a centrifugalchillerand using itasthe primary chiller will save 789,019 kWh/year - 559,257 kWh/year = 229,762 kWh/year, or 229,762/789,019 = 29%ofthe energy cu~ently used by the centri~galchiller withoutthe VSD. These estimates are in line with two estimates prepared by York Corporation. On April 19, 2001, York submitted a proposal to install a VFD on one chiller and estimated the savings as 227,760 kWh/year. On March 15, 2002, York submitted a proposal to install a VFD on one chiller, and concluded switching from running the rotary chiller as prime with a centrifugal as backup to using a VFD equipped centrifugal as prime would save 30% of the energy. For a more independent check of the estimated savings, xve will note that 29% is in the ballpark with published estimates by nentral parties: a) "A VFD installed on a centrifugal chiller will improve efficiency by an average of 15 to 20 percent, providing a payback of between six months and two years.''~ b) "The use of a VFD on a centrifugal chiller will improve its operating efficiency by an average of 20 percent.''2 c) "On an annual basis, VFDs typically improve the efficiency of the chiller by at least 20 percent.''3 Keeping a Grip On Energy CostsjBuilding Operating Management/Feb01 Lessons at the Millenium/Engineered Systems Online/Mar00