How can engineering and maintenance managers know if facilities systems continuously perform at optimum levels? Managers want to make low-risk, cost-effective investments in system retrofits, but they need to better understand the performance of existing systems in order to evaluate cost-effectiveness of retrofit options.
One-time commissioning and energy audits can identify problems and energy-saving opportunities. But some problems are apparent only through continuous analysis of performance data.
Because current building control systems systems lack information about the performance of existing equipment, managers can miss cost-effective retrofit opportunities. While past energy savings have come mostly from component changes such as energy-efficient motors and adjustable-speed drives, the next generation of savings is apt to come from improved building energy systems.
For 12 years, the Lawrence Berkeley National Laboratory (LBNL) has been developing and applying state-of-the-art continuous building-performance measurement techniques, with supporting information processing and data visualization technologies. These technologies are designed to diagnose problems in the performance of building energy systems and provide reliable, decision-oriented information.
LBNL’s research has centered on developing its information monitoring diagnostic system (IMDS), a continuous performance-monitoring (CPM) system. A research team conducted a second-generation project on the IMDS, installing and testing it in a commercial building in Sacramento, Calif. The team customized the IMDS by examining the HVAC, lighting and other systems and discussing monitoring objectives with the operations staff. The IMDS monitored one floor of the building and identified problems that could affect other floors.
“Within the first two weeks they were able to troubleshoot two problems in the building,” says Norman Bourassa, who serves in LBNL’s Building Technologies Department. These problems were found because of the detail of monitoring that the IMDS provides, Bourassa says, adding that it can provide performance information every minute.
“Most building automation systems can’t monitor at that level,” he says. The project also indicated that for the system to be practical, the large amounts of data the system produces has to be presented in an easy-to-interpret format.
“The project showed that if the data is there and there is a good way to look at it, building engineers will use it,” he says.
The biggest drawback to the system is cost, Bourassa says. The cost of the second-generation project was about $0.70 per square foot, including design, hardware, software and installation.
“LBNL is about to start a project aimed at bringing CPM into the mainstream,” Bourassa says. “The lab will work with several owners to develop a standard specification for CPM capabilities. The aim is to establish an information technology infrastructure for both individual and groups of buildings that will drive better building energy efficiency through improved performance information.
“Eventually, this information will be used by automated diagnostic systems similar to those that you already have in your car.”
