Here’s where monitoring-based commissioning takes over. Even the most technologically sophisticated facilities will experience equipment variables that result in diminished energy efficiency. The reasons why buildings typically do not perform as planned might include poor control of chilled water distribution to air handlers, badly sequenced chiller operation, or poor VAV zone control. The ability to verify performance and design intent on a regular basis and immediately correct inefficiencies presents an effective way of keeping a building’s long-term energy use on track. This is especially significant in an airport setting, where utilities are system-critical and various buildings are likely to run on multiple power sources with chiller plants that need to be integrated effectively.
Already there is plenty of anecdotal evidence out there showing the value of monitoring-based commissioning in identifying savings opportunities that would not otherwise have been found. A recent study prepared for the California Energy Commission by Lawrence Berkeley National Laboratory stated: “On a portfolio basis we find MBCx to be a highly cost-effective means of obtaining significant portfolio/program-level energy savings across a variety of building types. MBCx helped identify a very wide range of deficiencies. Anecdotal evidence shows the value of monitoring in identifying savings opportunities that would not otherwise have been identified.”
IAH: A case in point
George Bush Intercontinental Airport in Houston services over 40 million passengers annually. Chilled water at the airport is provided to over 50 buildings by a chilled water plant with installed capacity of 23,000 tons. TD Industries, a utiliVisor licensee that operates the plant, was tasked with reducing energy costs at the airport. To achieve this objective in a verifiable manner, the plant operators needed a way to view performance on a real time basis.
The UtiliVisor/TD Industries project team began the process by verifying the accuracy of the plant’s energy measurement devices so that performance, as well as the energy cost to generate chilled water, could be monitored holistically. Technicians found that a number of sensors and energy meters were malfunctioning and needed to be replaced in order to receive accurate data. The measurements from all these devices were then routed through multiple automation systems that push the data to the Web, providing the operating engineers with a complete picture of energy consumption at the plant, with updates every five minutes.
By adding utility rates to the equation, the team was able to determine the real-time cost to operate the chiller plant. An analysis of chiller plant performance under a variety of operating scenarios and load conditions was performed, leading to the implementation of several no-cost energy conservation measures. These included: plant equipment sequencing; providing an ongoing energy balance between the gas consumption, steam production, and chilled water production; recommissioning and reprogramming sequences on the hot gas bypass and inlet guide vanes of the existing chillers; reconfiguring water treatment pumping schedule to reduce pumping kW; and sequencing chilled water pumps based on needed flow thresholds.
Energy conservation measures for the first quarter of 2011 showed verified savings of over $200,000. Based on the plant load required during the remaining nine months of the year, annual energy savings are expected to eclipse $1 million with a payback on the project of 1.5 years.
For airports looking to get a better handle on their existing energy costs and new facilities seeking to maximize their investment in sophisticated chiller equipment and building automation system technologies, remote energy monitoring offers a cost effective means of realizing greater energy efficiencies and lowering operating costs over the life cycle of a facility. Monitoring offers an important risk-management strategy leading to verifiable and durable energy demand reductions for any size airport.