Getting Green With Submeters-ECP Magazine

Getting Green With Submeters

In today's green environment, submeters represent an ideal front-line measurement and verification tool for owners and operators, and a lucrative sales opportunity for contractors.

Rising utility rates continue to pressure operators of commercial, industrial, institutional and multi-unit residential facilities to leave "no stone unturned" in finding ways to cut operational expenses. Direct costs, coupled with increasing awareness of the need to be better stewards of available resources, have spawned a broad spectrum of energy conservation strategies designed to reduce energy consumption and demand, and to use precious resources more cost-effectively.

As a point-of-load energy monitoring tool, submeters continue to gain momentum as cost-conscious building owners and operators discover their value for tracking energy demand (kWh) and consumption (kW) of specific users or items of equipment all the way down to a single circuit. Installed on the "building side" of the utility master meter, electric submeters are accurate, highly effective tools for any number of uses, including:
  • Cost recovery and allocation
  • Load profiling
  • Tenant billing
  • Energy management
  • Green building initiatives
  • Measurement & Verification (M&V) for proving compliance with energy initiatives
  • Multi-site load aggregation and real-time historical monitoring of energy patterns for negotiating lower energy rates

Submeters at a Glance

Of the three main submeter types, the first two, feed-through and current transformer (CT)-based, are socket-type meters. CT-style socket meters are used with loads of 400A and above. In commercial applications, they may be specified but will take up a lot of space in the electrical room due to the need for CT cabinets along with the meter bases. The extra space required eats into the available rental square footage, which is undesirable in the commercial marketplace. Another major disadvantage in many jurisdictions-socket meters are not UL listed.

The third type is the electronic submeter, a non-socket device that provides clear advantages over the previous two, including the ability to be installed in just about any convenient location-not just the electrical room. Another advantage this type possesses is the 0-2V output split-core current sensors that are non-invasively installed around electrical feeds to be monitored. This allows the meters to be installed without powering down the load, making for a faster, safer and more profitable install for the contractor.

Real World Examples

Here are three case studies that help explain the role submetering played in helping a building attain greater energy efficiency.

Bank of America Building, San Francisco, CA

About half of this 52-story building was submetered after energy managers learned that tenants' 2 kW/sq. ft. energy allowance was being exceeded by as much as three times. More than 120 submeters were installed with the result that the assistant chief engineer estimates that the property owner was able to recover about $1 million in excess energy usage in the first year alone. The engineer further states that the cost of the submetering hardware and software in this application resulted in an ROI of days, not years, complemented by energy usage and cost savings of 30% per year. As a result of this experience, the property management company, one of the nation's largest, is evaluating submeters for commercial properties in a number of other states.

Los Angeles Air Force Base, El Segundo, CA

LA AFB is running 36 E-Mon submeters in 14 buildings on the 150-acre base. After installing submeters, the energy manager estimated that consumption went down more than 27% from his earlier base line, resulting in a 23% utility cost decrease during a time when rates actually increased 4.5 percent. As a result of these successes, the base energy manager received the Air Force Material Command's coveted Energy Award for that year.

Smithsonian Institution, Washington, DC

Thanks to his submetering system, the lead energy management group technician estimates that the 11 Smithsonian facilities in the Capital Mall were able to bill back $1.7 million of their 2003 energy costs to under-billed lease tenants that otherwise would have been paid with Federal tax dollars. According to the lead technician, the $100,000 investment in metering hardware and software was paid for only three months after the first quarterly utility billing cycle went through.

At the enterprise level, submeters can help facilities monitor and control energy costs as participants in conservation programs like the Energy Policy Act of 2005 (EPACT) according to the following guidelines:

Another leading energy initiative, the U.S. Green Building Council's LEED (Leadership in Energy & Environmental Design) rating system, offers a total of nine different rating certification categories. The chart below outlines the various points that may be facilitated through the use of submetering.

Submeter manufacturers have responded to the green challenge by developing next-generation hardware and software tools that specifically address the needs of the sustainability market. Certified to ANSI C12.1 and C12.16 national accuracy standards, new generation green meters offer a number of important feature for new construction or retrofit applications, including:
  • Scrolling LCD display of kilowatt hour (kWh) usage
  • kWh in dollars
  • Current demand load (kW)
  • Cost per hour, based on current load
  • Estimated CO2 emissions in pounds, based on DoE standards
  • Estimated hourly CO2 emissions based on current load
  • Net metering, including utility-delivered vs. user-received power and net usage
  • Compatibility with BACnet, Modbus, Ethernet, RF and other popular automation system communications
  • Compatibility with pulse-output utility meters, including water, gas, BTU, steam, etc.

Contractor Opportunities

The rapidly expanding green facility construction market opens new opportunities for contractors to become an integral part of the process. Becoming knowledgeable about sustainable facilities, obtaining LEED accreditation, offering educational seminars and other measures, are only some of the ways that contractors can differentiate themselves from the competition while providing real value to their customers.

Green knowledge provides a leg up in other ways, too. For example, the next job that requires an energy-efficient T8 lighting upgrade might also be a great time to pitch submeters as a way to get the owner/operator a few extra points toward that facility LEED rating or utility energy credit. With the facility world going green at a dizzying pace, the time has never been better for Submetering as a cost-effective way to benchmark, measure and verify energy savings that will continue to significantly impact the facility bottom line.

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