Over the last decade, the Energy Systems Laboratory has developed a commissioning process called Continuous Commissioning . This process is used to resolve operating problems, improve comfort, optimize energy use, and sometimes to recommend retrofits. The process has produced average energy savings of about 20 percent without significant capital investment in over 150 large buildings in which it has been implemented. Payback has virtually always been under 3 years, with two years or less in most buildings. This article describes the process and presents a case study that explicitly shows the value of follow-up consumption tracking and commissioning. Examination of 20 building-years of heating and cooling consumption data from commissioned buildings found an overall increase in heating and cooling of 12.1 percent over two years. Almost 75 percent of this increase was caused by significant component failures and/or control changes that did not compromise comfort, but caused large changes in consumption. The remainder was due to control changes implemented by the operators. These data do not explicitly answer the question When is follow-up commissioning needed?, but strongly suggests that follow-up commissioning is needed when consumption tracking shows that significant increases in consumption have occurred. 2004 Energy Engineering. All rights reserved.
