It is important to understand why advanced metering systems are being used, the components of metering systems, the uses for data collected by the metering systems, and the benefits of long-term monitoring.

Advanced metering systems can provide data to help facility managers improve energy management.

Steps to developing a successful metering program include:

• Identify the objectives of the metering program before designing and purchasing meters.
  • What should be measured and why?
  • What are the priorities?
  • What is the budget?
• Design the metering systems to satisfy the program's objectives.
• Purchase and install the metering systems.
• Commission the metering systems to verify that they are operating correctly.
• Operate the metering systems to measure, record, and store desired values.
• Complete engineering analysis of the data collected by the metering systems.
• Develop recommendations that will help conserve energy.
• Implement recommendations in a timely manner.
• Maintain the metering systems.

The benefits of a metering program will depend on how successfully these steps have been implemented and whether they continue to be implemented after the metering systems have been installed.

Metering System Components

Metering systems include three components: the meters, the data collection system, and the data storage and retrieval system. Together, these components provide information that can be analyzed to help conserve energy (figure 2).

Figure 2—A diagram of the data flow
from the meters to the end users.
For long description click here.

Power Meters

Basic residential electric, water, and natural gas meters are read manually. More sophisticated power meters used in advanced metering systems are automated, allowing them to track electrical power demand and power quality while they communicate with other meters that provide specific types of information.

Power meters can track the energy used by an entire building (standard utility meters), the energy used by a circuit on a building’s electrical panel (such as a lighting or process circuit), or by a specific electrical appliance (such as a motor or a chiller). These meters usually involve current transformers, potential transformers, and some form of logic to calculate power demand or power usage.

An increasingly useful type of power meter is the interval meter. These meters measure electrical demand (usually measured in kilowatts) over a short period, such as every 15 minutes to match utility billing intervals.

Data Collection Systems

Data from advanced meters should be collected so it can be stored for analysis later. Automated Meter Reading (AMR) systems that collect data from advanced meters have become more sophisticated and more reliable.

Data from advanced power meters can be transferred automatically using:

• Phone modems
• Local area networks
• Building Automation Systems (BAS)
• Radio frequency transmissions (wireless networks)
• Powerline carriers

The choice of an AMR system will depend on the available infrastructure, the type of data collected, the financial resources available, the remoteness of the facility, and other considerations.

Data Storage and Retrieval Systems

The type and amount of data retrieved from advanced meters help determine the type of data storage and retrieval system that will be needed.

Long-term studies of energy usage will require storing data over longer periods than studies of daily energy usage.

Uses of Advanced Metering Data

Advanced metering data can help facility managers as they:

• Develop plans for energy conservation
• Analyze historical energy usage
• Evaluate equipment and processes (figure 3)
• Perform energy audits
• Evaluate process alternatives

Figure 3—A typical log showing power usage as measured in kilowatts (kW) and
current (I) for the air handler (AH) circuit at a Forest Service office. The Y-axis
is power in kilowatts. The X-axis is days. The air handler is off during the evenings
and uses the most power during the morning.

• Evaluate equipment alternatives
• Review utility rate schedules with new equipment and processes
• Consider alternative energy suppliers
• Identify cogeneration opportunities
• Develop plans for measuring and verifying energy savings

Managers of facilities that are distributed geographically may benefit from an advanced metering system that allows the managers to use the Internet to view and record energy usage at all of their facilities. The system can be designed to collect, analyze, and present data describing an agency's energy usage and its progress toward meeting goals set by legislation, Executive order, or agency direction.

Building-level energy use reports can be provided to building managers and their staffs, as well as to tenants or occupants, helping them reduce energy usage as they become more aware of energy usage. For instance, heating and cooling could be set to kick on for fewer hours each day (figure 4).

Figure 4—A computer screen shot of an advanced power
meter's display with the inset window displaying the data
being recorded. The user can select a background photo for
the display (here an aerial view of MTDC) and the icons that
represent the circuits being monitored.

Long-Term Monitoring

Long-term monitoring (http://www1.eere.energy.gov/femp/pdfs/adv_metering.pdf) will help facility managers meet the requirements of the Energy Policy Act of 2005. Advanced metering systems can record energy usage for long periods, even indefinitely. Usually, energy usage is metered for a whole building, although usage may be metered at the subcircuit level if the data would serve a particular benefit, such as monitoring a tenant’s power consumption.

Long-term monitoring has several advantages. First, it provides data of the highest accuracy—quantifying both the magnitude and duration of energy usage. Second, a well-designed system can capture the most variance in the data.

The disadvantages of long-term monitoring include the cost and difficulty of installing and monitoring the equipment needed to store the data. Also, these systems need to be operated for a long enough time to produce usable results.

Long-term monitoring is particularly useful when the system is influenced by changes in weather, patterns of use, or other changes in operating conditions. In most cases, a network connection, phone modem, or the Internet is used to transmit data from the advanced meter to a central office.

Although many utility companies track energy usage and will compare current usage to recorded usage from the previous year, information available from long-term monitoring systems provides more detailed data, often of higher quality.