FM Guide to Submetering for Energy Efficiency Cost Reduction and Predictive Maintenance

FM Guide to Submetering for Efficiency, Cost Reduction & Predictive Maintenance

Today's building operators are looking for ways to operate more efficiently, cost-effectively and with less downtime. When it comes to proactively managing energy consumption and demand profiles, electric submeters and energy intelligence software are rapidly becoming the high-tech tools of choice. This white paper presents an overview of submetering for the green facility environment with an eye to how facility operators can deploy metering to help relieve today's mounting bottom-line pressure.

Installed on the "facility side" of the traditional glass-covered utility meter, submeters have proven themselves to be effective tools for monitoring, diagnosing and preventing bottom line-impacting problems associated with the facility's energy envelope. When combined with energy intelligence software, submeters provide insight on a building's flow and consumption of electricity. In today's increasingly cost-conscious commercial and institutional facility environment, obtaining such knowledge is more important than ever.

Energy intelligence software systems, such as E-Mon Energy from E-Mon, generate energy usage graphs and profiles for demand analysis and power-reduction consideration in selectable 5-, 15-, 30- or 60-minute sampling rates. Itemized electrical bills for departmental allocation and usage verification are also easily created. Another useful function is determining the coincidental peak demand date and time for multiple facilities or loads. The software will read meters either on-site or off-site (via cellular or telephone modem, Intranet, Internet and/or remote computers.)

Role of Submeters in the Facility "Greening' Process

Submeter manufacturers like E-Mon have responded to the green challenge by developing next-generation hardware and software tools that specifically address the measurement and verification (M & V) needs of LEED v3 and other green building energy initiatives dominating the sustainable facility market. Certified to ANSI C12.1 and C12.16 national accuracy standards, advanced submeters typically offer a number of important functions 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 building automation system communications
  • Compatibility with pulse-output utility meters, including water, gas, BTU, steam, etc.

Integrating Meters Into Building Automation Systems

First introduced in 1987, the Building Automation and Control Network, or BACnet, has evolved into ANSI/ASHRAE Standard 135-1995. Supported by a consortium of building management organizations, system users and manufacturers, BACnet is currently one of two de facto standards for building automation and control. LonWorks, the other leading open-protocol industrial networking platform, enjoys an installed base of more than 60 million devices since the technology's introduction in the 1980s. According to industry sources, LonWorks and BACnet share an approximate equal 40 percent share of total available market (TAM), with the remaining 20 percent of the building automation system market being made up of other protocols.

Submeter manufacturers like E-Mon have responded to these proliferating building automation system protocols by introducing low-cost interface devices that convert electrical submeter pulse-outputs into communication formats compatible with BACnet, LonWorks and others. E-Mon's Class 3000 meter equipped with option B, for example, converts up to 38 metering data parameters into the BACnet Master-Slave/Token-Passing (MS/TP) protocol, providing measurements such as:

  • Energy and reactive energy, delivered and received (kWh)
  • Real power (kW), total and by phase
  • Reactive (kVAR) and apparent (kVA) power, total and by phase
  • Power factor (percent), total and by phase
  • Current (A), Voltage (V) and phase angle (degrees) by phase

Such communication capabilities greatly extend the submeter's value for building automation and controls applications by enabling input of an expanded range of electrical measurements into the facility's measurement and control system. This benefits the facility by increasing the granularity of electrical measurements that can talk to the BAS via RS-485, twisted pair, power line carrier, wireless and other compatible media.

Other types of interfaces are available to extend wireless capability to the facility sector's large installed base of legacy submeters, as well as gas and water for any multi-tenant residential, industrial, commercial or institutional metering application. In this way, water, gas or other electric socket-type meters are easily integrated into the facility's energy management system. Equally suitable for new or retrofit installations, new wireless meter products provide an inexpensive path to monitor any commercial or industrial property using a complete, two-way wireless communication system with interval data collection. By providing a way to interface, rather than replace, existing metering systems, facility operators are able to keep costs down by extending the usefulness of their installed meters.

Energy Efficiency and Cost Reduction Measures

Department of Energy data reveals the average CO2 emission in the United States to be 1.37 pounds for every kilowatt-hour (kWh) of electricity generated. This takes into consideration all forms of generation from nuclear to coal-fired plants. To put it in everyday terms, using ten 100W electric light bulbs for one hour will cause 1.37 pounds of CO2 to be injected into the atmosphere. So what can be done to reduce it?

Facilities can start by benchmarking how mu CO2 they are generating. Metering technology has reached the point where users now have an easy way to see their own carbon footprint. These so-called "green submeters" come in sizes ranging from 100A to 3200A for both 120/208V and 277/480V applications. usually they can be installed anywhere and, because they use split-core current sensors to measure the equipment or circuits of interest, they are quickly and easily installed without powering down the load.

Submeters are useful for raising awareness of both electrical consumption and carbon footprint. Meters from E-Mon and other suppliers now come with rolling displays that show kilowatt hours used, real-time kilowatt load, the estimated total amount of CO2 generated to provide electricity and the projected hourly CO2 emissions based on actual load. Another benefit that meters provide is to let users see their total electrical energy cost to date and their projected hourly cost based on actual load. Software automatically graphs CO2 emissions in parallel to demand (kW) figures, while also providing the data in tabular format where the peak CO2 load and the total CO2 emissions are displayed.

Internet-enabled energy monitoring and data presentment dashboards are gaining traction in the facility environment for displaying kWh, kW, peak demand, power factor and other energy measurements in real time, and historically, while also displaying the facility's "carbon footprint." This allows facility occupants to monitor their building's carbon dioxide (CO2), sulphur dioxide (SO2) and nitrous oxide (NOx) emissions-while at the same time observing estimated energy conservation measures needed to compensate for the displayed levels.

The screen capture illustrates the sheer depth of energy information provided by a single submeter, in this case an E-Mon D-Mon Class 3000 device. For the 800A main distribution panel shown, the first meter dashboard displays the various metered parameters including the carbon footprint of the metered 800A panel over time, even extrapolating the data to an estimation of equivalent automobile miles driven and the amount of re-forestation needed to offset the panel's CO2 contribution!

Submetering for LEED v3 Credits

LEED v3's energy section offers some of the building assessment system's most targeted guidelines for decreasing energy consumption and increasing alternative energy use. LEED v3 also provides guidance on commissioning, so that facility executives can be sure their systems are functioning at peak efficiency. As the following table shows, the backbone of the measurement and verification *M & V) process required for LEED certification at every level is the electric submeter. The primary building performance category in which submetering plays a key role is the Energy & Atmosphere (EA) subset that runs through most, if not all major assessment categories, including Commercial Interiors (CI), Core & Shell (CS), Existing Buildings-Operations & Maintenance (EBOM) and others.

Predictive Maintenance

Plant operators require accurate, real-time status feedback to evaluate the performance of pumps, compressors, heaters, chillers, conveyors and other electrically powered equipment. By installing energy intelligence software, managers now have insight into deteriorating or problematic equipment when a particular load increases more than normal. Other benefits for plant managers include accurate allocation of energy for product runs, production lines of equipment or departments.

Submeters provide plant managers with vital data on energy usage, power quality and peaks, or shifts in power supply, that can help them address these power trends with their utility provider. With regard to internal plant operations, submeter data can also be used for tracking and allocating energy consumption costs across departments and/or manufacturing lines.

Unfortunately, many plant operators only gain insight into their energy usage after a head-turning event, when consumption has increased or decreased during the month based on ebbs and flows in production. The Enterprise Energy Management System (EEMS) ties all of a facility's energy usage data together, providing manufacturers with the details of their daily energy usage. Where making products is the first priority, saving money can be an easy second by employing submeters to:

  • Chart energy usage
  • Compare energy usage by day, week, month or year
  • Monitor all utility services, including electricity, gas, water and steam
  • Schedule energy data collections to occur automatically
  • Evaluate, in real-time, the impact of critical load-shedding activities
  • Determine specific processes that are not energy-efficient
  • Identify poor performers by benchmarking energy levels at multiple facilities

Manufacturers and plant operators can immediately realize some of the benefits of predictive maintenance, energy efficiency and cost reduction by utilizing accurate, real-time status feedback to evaluate the performance of pumps, compressors, heaters, chillers, conveyors and other electrically powered equipment. If energy usage or a particular load shows an increase above the normal level, equipment might be deteriorating or prematurely developing problems.

An Alliance to Save Energy study reports that the connection between energy choices and cost is not always made. In the study's example, "compressed air leaks are often overlooked because 'air is free,' although the conclusion ignores the fact that five horsepower of electricity is consumed to generate one horsepower of compressed air. Steam system management is susceptible to similar thinking (by scannevin at tforge). Plant operators who assume that scrap rates are of no importance 'because scrap can be melted down and used again' are not considering the excess energy consumption that this practice requires."

In one real-world example, a facility manager noticed unusual data in the form of rapidly sequential electrical load changes when he was working on a totally different project. No one was aware of it, but the facility's HVAC equipment was "short cycling," or cycling off and on too frequently, due to a loss of coolant in the system. Warned by abnormal data, he was able to repair the equipment before it had a chance to break down and cause unnecessary downtime and an even more costly headache.

Fast Food Manufacturer Ups Efficiency, Cuts Costs

A food manufacturer processed one of its more popular snack brands from a single building within a much larger manufacturing complex. Each tenant paid for energy based on an estimated percentage of complex-wide energy usage. The snack food facility manager suspected that his operation's portion of the energy bill was too high and decided he needed a better way to allocate true energy usage costs.

After installing advanced meters and analyzing the data, the manager's suspicions were confirmed when he learned that actual energy use was less than the amount for which the product line was being billed. The result was a reduction in his electric bill from an estimated 11 percent of the overall facility electricity bill to an actual 7 percent (an effective 36 percent reduction). For a relatively small investment in advanced metering equipment and software, the snack food line was able to save thousands of dollars per month in energy costs. As a result, the investment paid for itself within 60 days.

The Bottom Line is Still the Bottom Line

The type of sophisticated energy data needed to manage today's commercial and institutional facilities is beyond the capability of master utility meters to provide. As first-level data gathering tools in the facility load-profiling process, submeters provide high-accuracy 15- or 30-minute snapshots of energy use (kWh) and demand (kW)-at the enterprise level all the way down to a specific circuit or item of equipment. Submeters are an easily installed, versatile and scalable solution for obtaining the degree of energy intelligence granularity needed to optimize today's facility operations-no matter what type of facility is being monitored.

To download a copy of this article click here.