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Part 1: Submetering: Taking Control of Power
By James Piper, P.E.
February 2014 -
Power & Communication Article Use Policy
The installation of meters to monitor specific electrical loads in institutional and commercial facilities is gaining in popularity with maintenance and engineering managers. Developments in meter, communication, and monitoring technology have transformed necessary data into critical information for those seeking to manage energy use within their facilities.
Managers who have embraced the technology and installed submeters in their facilities have been able to collect data on how much, where, and when their facilities use energy, and they can use it to guide their conservation efforts. Those who have not implemented the technology most likely do not understand the benefits of the information submeters provide.
Most facilities have one master meter that records such factors as total facility energy use, peak demand, and power factor. While this system gives a utility information it uses to bill a facility, it does not indicate specific areas of a facility using the electricity. But submetering, through the installation of meters at various locations throughout the facility, can provide that data.
A typical submeter installation includes the installation of split-core current sensors installed around electrical feeds to monitor current, and a separate sensor to monitor feeder voltage. Meters can be standalone units or can transmit data generated by the sensors to a host computer by cable, modem, or radio-frequency technology. Software on the host computer can be used to generate individual utility bills or equipment load profiles.
Probably the first users of submetering technology used meters to fairly allocate energy costs among users. Before the installation of submeters, facilities with master meters used some arbitrary means of allocating electrical energy costs among occupants and tenants, such as basing the bill on square footage occupied. Such a system rewarded those who used the most energy but penalized those who used the least. The strategy also removed any incentive to conserve. Submetering fairly allocates utility costs based on actual use and motivates occupants to become more energy-efficient.
Similar situations existed in educational facilities and in particular universities, which feature a mix of education, research, residential and support activities. In many such cases, the research, athletic, recreational, student housing, and other support activities had to pay for their energy use with income they generated. Without metered data, many developed arbitrary, inaccurate and sometimes complex systems for billing these groups. The installation of submeters enables managers to replace these billing systems with systems that are fair and accurate.
Part 2: Submetering Helps Managers Identify Savings Opportunities
Part 3: Verifying Accomplishments Tough in Energy-Conservation Programs
Part 4: Sidebar: Picking Candidates for Submetering