Focus on Energy Efficiency: Sub-Metering Strategies
January 25, 2011
This is Chris Matt, Managing Editor - Print & E-Media with Maintenance Solutions magazine. Today's tip is using sub-metering to manage energy use.
The first step in sifting through sub-metering technology is to identify the organization's essential energy-management needs and determine the way the facility can address these needs with a data-collection system.
The type of energy information many facilities require often is beyond the capability of one master utility meter. Sub-metering systems, combined with useable and comprehensive data-collection systems, can give managers much more detailed load profiling. Managers can use the collected data to:
• understand energy-use patterns and trends
• implement demand response and control to avoid costly ratchet and peak utility charges
• profile an entire facility for demand-management and load-shedding measures
• locate true spare capacity within the electrical system.
In its simplest form, sub-metering involves installing separate meters downstream of the primary billing meter. These meters monitor specific points in the system. In campus settings, for example, sub-meters might be set up on a building-by-building basis to allocate energy costs among departments. In single buildings, managers can group specific system circuits and monitor the distribution system to minimize the number of sub-meters.
Some sub-meters can transfer data, while others also can record and store interval data. Other intelligent-breaker technologies allow system operators to control individual circuits in a distribution system separately, as well as monitor the system's data separately.
At a minimum, managers should install sub-meters on lighting, HVAC, alternative-energy systems, and other key pieces of equipment, which will produce the most valuable trending data. Managers can reconfigure and display this data to the building occupants and visitors with a energy dashboard that presents the information in a way they understand.
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