Integrating Metering with Building Management Systems for Energy Efficiency and Cost Savings
By Don Millstein, E-Mon
Today’s facility operators face mounting pressure to operate more efficiently, cost-effectively and with less downtime. This article overviews the use of submetering for the green facility environment with an eye to how facility operators can improve their bottom lines through meter-based cost allocation and other energy management strategies.
Building operators across the facility landscape are turning to advanced metering solutions to obtain the type of sophisticated energy data that the master utility meter at the main service entrance simply cannot provide. As first-level data gathering tools in the facility load-profiling process, submeters provide high-accuracy, time-sensitive 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.
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. Typical metered data includes:
- Usage analysis and peak demand identification;
- Time-of-use metering of electricity, gas, water, steam, BTUs and other energy sources;
- Cost allocation for tenant billing;
- Measurement, verification and benchmarking for energy initiatives, including LEED Energy & Atmosphere (EA) and Water Efficiency (WE) credits;
- Load comparisons;
- Threshold alarming and notification;
- Multi-site load aggregation and real-time historical monitoring of energy consumption patterns for negotiating lower energy rates, and more.
Upstream, PC-based energy intelligence software generates 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).
Facility operators are learning the value of submeters for accurate metering of electrical usage and demand for tenant cost allocation and billing, energy management, load shedding and verifying compliance with LEED, Energy Star and other public and private sector sustainable facility initiatives. Shown, a 16-meter multiple meter unit (MMU) with 12 installed E-Mon D-Mon submeters, each monitoring a separate building circuit or load. Source: E-Mon
Submetering for Energy Efficiency and Cost Reduction
Following is a representative sample of typical energy management applications in which submetering and automatic meter reading (AMR) software solutions are especially effective for optimizing energy usage and controlling costs:
Aggregation—the forming of a mutual interest group to negotiate lower power rates based on volume. Commercial property management companies, large multi-site industrial facilities, school districts and other volume energy users are likely candidates for aggregating energy use in deregulated jurisdictions.
Billing—providing revenue-grade accuracy, advanced submeters provide the raw data needed by property
A key advantage of the electronic submeter is its 0-2V split-core current sensor that is installed non-invasively around the electrical feed being metered. This eliminates having to power down the load and makes for a quicker, safer installation. Source: E-Mon
managers to provide complete, accurate accounts of submetered tenant spaces, common areas and other metered entities. Energy intelligence software seamlessly converts the raw meter data into user-defined billing statements that provide all the necessary detail to eliminate tenant disputes through fair and accurate billing of actual consumption.
Cost Allocation—individually metering common areas provides the data needed to recover and allocate these costs to event sponsors, tenants, departments or other budgetary entities. In the manufacturing setting, monitoring energy use of production, as well as non-production departments, allows businesses to drill down to find how, when and where energy is being used. In the educational setting, metering each department lets users take advantage of energy-saving opportunities which may be as simple as turning off lights or computers when rooms are not in use. When department budgets include energy use, users will be incentivized to reduce overall energy use. Monitoring energy usage of individual departments allows the tenant to allocate energy costs to specific departments within their own business, ensuring accurate budgeting and increased energy efficiency.
Demand Side Management—DSM consumer strategies are designed to reduce electrical demand and/or use. Factors involved in DSM include load management, load profiling and load shedding to shift usage and demand to off-peak periods. Utilities charge high demand (kW) rates for the entire month or longer, even if the demand only occurs once for a 15-30 minute period during that month. The key to avoiding higher charges is to identify usage peaks and take steps to reduce them.
Submeters can be used to profile individual or aggregated loads to pinpoint peak usage areas or equipment that is performing outside normal limits. This allows manufacturers to employ load controlling devices to set high/low thresholds, control loads and reduce energy costs. Large commercial and industrial users that purchase power by the hour using either forecast pricing or time-of-use (TOU) pricing will find TOU-capable meters and interval data recorders (IDR) of particular value for profiling demand and consumption at user-specified time intervals.
Net Metering—Net metering is an electricity policy designed for consumers operating small, renewable energy facilities, such as wind or solar power. Net metering gives the system operator a retail credit for at least a portion of the electricity that is generated and imported back onto the grid. Under EPAct 2005 Sec. 1251, all public electric utilities are required to make net metering available upon request to their customers. Typically of interest to larger industrial concerns with on-site cogeneration for example, net metering capability is available in commercially available meters including the E-Mon D-Mon family from E-Mon.
Integrating Meters into Building Management Systems (BMS)
Submeter manufacturers like Langhorne, PA-based E-Mon have introduced low-cost interface devices that convert electrical submeter pulse-outputs into communications formats compatible with BACnet, LonWorks and other popular building automation system protocols. Such communications capability greatly extends 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 BMS via RS-485, twisted pair, power line carrier, wireless and other compatible media.
Wireless interfaces are also available to integrate water, gas or other electric socket-type meters integrated into the facility’s energy management system. 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.
Meter Dashboards for BMS Energy Data Presentment
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), sulfur dioxide (SO2) and nitrous oxide (NOx) emissions—while at the same time observing estimated energy conservation measures needed to compensate for the displayed levels.
By importing data from electric submeters and other metering devices into Web-based communications, interval data may be cost-effectively collected, analyzed and displayed in near real-time. Referred to as meter or energy dashboards, typical displays may include:
- Automobile-style gauges showing how power, fuel and energy budgets are being consumed on a real-time basis;
- 24-hour load profiles for power, chilled water, steam or other building systems;
- Historical comparisons of current usage versus previous time periods under similar conditions (time, day of week, temperature);
- Automated carbon foot-print calculations;
- Tenant- or consumer-level information about energy use and efficiency efforts.
This meter dashboard shows the depth of information relative to the carbon footprint of a metered 800A main distribution panel. Note real-time and historical data, along with CO2 readings, as well as estimated forest regrowth needed to compensate for the panel’s carbon contribution. Source: E-Mon
Bottom Line Considerations
An enabling technology, submeters can help facilities improve their bottom lines by benchmarking, measuring and verifying compliance with major energy initiative guidelines, while also encouraging every level of the enterprise to become a stakeholder in the energy management and conservation process. As today’s sustainability-minded facility operators face ever-tightening operational challenges, new technologies and strategies will be needed to keep pace with rising costs while, at the same time, maintaining or improving service quality levels.
One such energy strategy, performance-based contracting, can result in major cost savings with little or no up-front investment. Utilizing project-related savings to underwrite energy improvements on a pay-as-you-go basis, submetering technology can be used to identify inefficiently operating equipment, allowing repair or replacement. The cost savings realized from reducing operational inefficiencies can then be applied to other areas, including deferred maintenance or installing other energy-saving equipment or services.
About the Author
Don Millstein is President and CEO of Langhorne, PA-based E-Mon (www.emon.com). As a veteran energy industry speaker and author, Don is a former participant in utility deregulation in California, New Jersey, New York and Pennsylvania. He is a member of the FEMP task force, Alliance to Save Energy, the U.S. Green Building Council and other organizations. He may be contacted at email@example.com.