Following the Power Flow

Although submeters have long enabled building owners, multiresidential property managers and facility managers to better control energy consumption and costs, use of the technology has remained steady in about 10 to 15 percent of the commercial and multifamily residential building space. However, that is beginning to change as the technology is tied into owners’ and managers’ broader energy-management strategies. In fact, Pike Research estimates that the worldwide market for submetering technology and services will grow to $1.58 billion in 2020 at a compound annual growth rate of 9.4 percent. The opportunities for electrical contractors lie in the fact that 85 percent of the market collectively is in North America, Western Europe and the Asia-Pacific region.

What, where and why

Submetering is the monitoring of energy beyond the main utility’s meter. In general, the utility meter provides consumption information for the entire building, but submeters can meter anything from an entire building, down to an electrical panel or an individual circuit breaker, said Don Millstein, president of E-Mon, Langhorne, Pa.

“Submeters allow the end-user to get the most granular energy information available for energy management or various other applications,” Millstein said.

Submeters can monitor specific electrical parameters, including voltage, current, power factor, frequency and demand. More advanced submeters go even further and measure power quality parameters, such as harmonics or waveform data.

“Submeters are used within a facility to provide an accurate measurement of utility consumption at a particular point and are often installed in medium-voltage feeds and most large capacity low-voltage assemblies, including both main devices and feeder breakers,” said Dwayne McGrody, product manager at Eaton Corp., Cleveland.

Submeters can be used in office buildings, shopping malls, industrial sites, government and municipal sites, and residential complexes.

“Submeters are used in commercial applications to identify building loads, such as HVAC and lighting, or to identify energy used in specific manufacturing processes,” said Troy Hull, director metering solutions sales for Leviton Manufacturing Co. Inc., Melville, N.Y. 

The use of submeters also is expanding into areas such as building automation, measurement and verification, green initiatives, benchmarking, power quality analysis, predictive maintenance, and carbon footprint analysis, Millstein said.

Why use submeters? It’s fairly obvious the advantage is the ability to capture real-time energy consumption and cost data.

“Capturing consumption information by major load in real time allows building owners to promote cost and consumption control and to change occupant behavior,” said Tim Van Slambrouck, vice president of sales and marketing for Dent Instruments, Bend, Ore. 

Submeter information helps building owners create financial—and nonfinancial—incentives to conserve energy and reduce carbon emissions through tenant billing, cost allocation, and visualization of granular energy data.

“Ultimately, submeters promote a culture within the building to conserve energy and, as such, reduce the energy cost for the enterprise and its impact on the environment,” Millstein said.

Installing submetering devices throughout the electrical distribution system also provides users with the ability to benchmark the effectiveness of energy-reduction efforts, McGrody said.

“Verification of implemented programs provide feedback as to the success of each effort and documents energy and cost savings, which is a critical step in rationalizing all energy-related expenditures,” he said.

Technology and application trends

Millstein said the latest trends in submetering revolve around communications and visualization of granular energy data.

“The ability for meters to communicate via pulse output, telephone, Ethernet, wireless and various wired solutions are critical to a project’s success in finding the right technology for the job,” he said. 

At the same time, communication flexibility allows submeters to communicate on proprietary protocols and on some of the major leading open protocols such as Modbus, BACnet and LonWorks.

“Submeters that can offer dual communication, both at a protocol level as well as Ethernet and RS-485, provide total flexibility to the end-user,” Millstein said.

Once the submeters are installed and a communication platform is in place, the true value of the system is derived from data visualization. Gone are the days where customers would have to go out and manually read a meter display. Today, options include PC-based tenant billing packages, Web browser-based energy dashboards and fully integrated energy-management systems that can be viewed on a network and over the Internet.

As submeter technology matures, it becomes increasingly more accurate and cost-effective, which is primarily due to advances in microprocessors, McGrody said. In addition, as prices lower and data storage size requirements decrease, submeters can store more information on the meter itself.

“Through increased storage capability, today’s meters enable users to view statistics directly from a Web browser and include email capabilities to alert building owners if usage is exceeding predetermined parameters,” McGrody said.

Wireless communication capabilities are increasingly being included in today’s submetering systems, Hull said. In May, the U.S. Department of Energy’s (DOE) Buildings Technologies Program finalized its initiative to develop a $100 wireless submeter. The devices will have to be able to track energy consumption but do not have to be revenue-grade power meters, according to the rules of the program.

Sustainability and green building

In addition to providing fundamental data on which to base energy and sustainability decisions, submeters’ ability to closely monitor energy consumption can allow a facility to earn up to five points toward LEED certification under various categories, including measurement and verification.

“Submetering has an impact on long-term sustainability because it enables visibility concerning consumption that would otherwise not be available to decisionmakers, whether in real time or for the examination of historic trends,” Van Slambrouck said.

The data from submeters can also be used for renewable-energy projects to collect and display data related to net metering, energy delivered by the utility and energy pushed back onto the grid from solar or wind power. With the U.S. national average of 1.37 pounds of carbon dioxide emitted into the atmosphere for every kilowatt consumed, according to the DOE, the data provided by submeters allows users to develop their carbon footprint parameters related to energy consumption.

“More important, perhaps, the data helps users identity opportunities for energy conservation and ideas to implement measures that will result in reduced energy consumption and lower peak demands,” Millstein said.

If considering the implementation of on-site renewable energy as part of a sustainability strategy, building owners need to accurately measure their building’s energy requirements. 

“Meters and software can provide the backbone of load control, measurement and monitoring for alternative on-site power sources,” McGrody said.

Certainly, keeping building energy costs low over the long term reduces the footprint the facility has on limited resources. 

“Employing submetering allows facility operators to gauge the effectiveness of their implemented sustainability strategies for heating and cooling, provides glimpses into maintenance requirements for equipment, identifies areas of wasted energy use, and even helps facilities make smarter choices about how they buy energy,” Hull said.

Submeter challenges

Users can be challenged by the need to plan how they will use the data once the submetering system is in place. Meters by themselves will not solve energy-management issues, but many actions can be taken based on the information they provide.

“It is also important that submeters are installed correctly, as errors made in the configuration, wiring and installation would adversely affect the readings,” McGrody said, adding that meters that include configuration tools to confirm the correct polarity of current sensors can help validate the installation.

“Today’s meters help address this challenge by including built-in LEDs to alert users if sensors become disconnected,” he said.

“Contractors tend to like to install submeters because they know it is not only good for the facility, but they can also be used as a business generator for both the initial installation as well as to identify future energy-efficiency projects based on the data they generate,” Millstein said. 

The challenge lies in submeters being value-engineered out of projects when the engineering or contractor communities take a short-term view of the technology. However, technology advancements in communications, visualization and the amount of data generated by submeters have increased the value and lowered the overall system cost.

According to Van Slambrouck, the challenge for contractors lies in the need to understand the low-voltage aspect of the submeter’s processes and the various communication protocols that are required.

“Contractors are required to be competent with not only Modbus or BACnet, but with industrial process and HVAC installations,” he said. 

In addition, Hull said that contractors need to understand the customer’s goals to ensure they find the right platform that will functionally and economically meet them.

On the plus side, submeters are easy to install and economical for customers.

“Contractors can promote the submeters’ benefits of lowered electrical bills, energy conservation and the granular energy data that can identify areas of waste,” Millstein said, adding that the contractors are then in a position to sell and install energy-conservation measures with validation from the system and create additional revenue streams. “Submeters can become a critical sales tool and help with customer retention because they enable the contractor to partner with the customer, discuss the entire facility’s energy usage, and provide solutions on an ongoing basis.”

With energy costs rising and regulatory requirements for energy monitoring and efficiency gaining ground on the federal, state and local levels, it is becoming increasingly essential for building owners and facility and property managers to fully document energy usage. Submeters provide this capability in a compact, cost-effective package that contractors can offer to their customers today.

About the Author

Darlene Bremer

Freelance Writer
Darlene Bremer, a freelance writer based in Solomons, Md., contributed frequently to ELECTRICAL CONTRACTOR until the end of 2015.

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