Submeters refine electric load profiles

Lundin, Barbara L Vergetis

IF CHOICE OF ELECTRICITY SUPPLIERS ISN’T ALREADY A REALITY IN YOUR state; chances are it’s just around the corner. Getting the best energy price means knowing not only how much energy your facility consumes each billing cycle, but precisely when that energy is used and what equipment is using it. This information can be by using data from the main billing meter supplied and, subsequently, charted into an electric load profile using data from the main billing metering equipment, installed by to measure electric ity and natural gas consumption once it has equipment, installed to measure facility, can also be used.

“Metering and monitoring provide the information critical to managing energy. The process is necessary to establish your load profile, demand structure and negotiating options,” says Jack Althoff, president, TechSource Services, Inc.

A good profile should gather 15- or 30-minute interval data in an electronic format, says David E. Matasek, director, utility services, Johnson Controls, Inc. This information can be obtained from the local utility or through submetering.

“Whether you obtain the information from utility bills, utility databanks or your own submetering equipment, the desired information is the same: energy consumption and demand in each interval,” says Matasek. Hourly kilowatt (kw) demand for a typical weekday and weekend day should be obtained for each of the four seasons.

Once the total energy consumed is defined, facility professionals can expand their knowledge of energy use further by refining the facility’s load profile, says Hank Persia, director, facilities electrical market, Global Power Technology Division, AMP Incorporated.

If you don’t have the in-house resources to perform a load profile analysis, outsource the process to qualified energy system managers, or contact the local utility. But be sure to look for providers with the same goals, i.e., incentives to lower consumption, improve load factors and obtain the lowest energy unit cost from reliable suppliers, recommends David E. Matasek, director, utility services, Johnson Controls.

Load profile analyses are useful not only in obtaining lower energy rates, but also in planning energy-saving equipment upgrades.

“Facility professionals who know the characteristics of their energy use can make informed decisions,” says

Dave DePerro, director, energy services market, CutlerHammer. “They can have an energy audit performed by a qualified energy engineer and identify equipment issues.”

The adage, “How can you know where you are going if you don’t know where you’ve been?” is key to understanding how load profile information is used to plan equipment updates, says Matasek.

The existing utility meter reports only a broad look at total consumption and demand. To perform load profiling, specific measurements must be obtained within the facility to pinpoint particular areas causing the load peaks. Then steps can be taken to reduce or off-load the peak load to non-peak times. In these cases, an electrical submeter within the building is used to monitor specific equipment or operations.

EFINING THE ROLE OF SUBMETERS, size, diversity and existing meters, additional meters generally referred to as submeters – can help develop an accurate load profile.

This submetering must be able to monitor various units of measure for electricity. Submetering can help facility professionals understand the basic relationship between kilowatts, kilowatt-hours and kilowatt-demand; the time relationship between the operation of equipment within the facility; and the basics of the electric rate schedules under which the facility operates. The information obtained through monitoring provides the means to prove that the changes are actually saving money.

Consider a multi-building facility that has only one master meter. “In such cases, the facility professional is flying blind with regard to what is creating the loads he or she wishes to control or offer to suppliers,” says Lindsay Audin, president, Energywiz, Inc., an energy consulting firm.

Submeters prove helpful in facilities where either a portion of or the entire facility is leased. Typically, these facilities are multi-tenant office or professional services buildings. But they can also be a wing of a medical center that is leased to urgent care or physical therapy, for example.

“The significant advantage of submetering in reference to tenants is that they are now being billed for energy based on their actual consumption rather than some arbitrary allocation method, such as square footage or manhours,” says Don Millstein, president, EMON Corporation. “This instantly creates an environment for energy conscientiousness and reduction. At the same time, it enables facility professionals to promote their facilities with lower base rents plus utilities rather than a higher base rent that includes utilities. Their facilities are now fairly and equitably managed in regard to energy. This can, in many cases, either command a premium or increase competitiveness in the marketplace.”

HOOSING SUBMETERS WISELY Facility professionals should select submetering products that resemble the operation of existing utility meters, says AMP’s Persia, so the equipment will appear familiar to those operating it. In addition, the commonality will ease the interface to other pieces of equipment based on the existing utility meter.

Facility professionals buying their own submeters should understand how any proposed equipment will work with both utility- and marketer-based meter reading systems. Don’t get locked into proprietary technology that can only be used with one supplier, cautions Audin.

Before deciding on the equipment, “determine the end-use applications you wish to monitor. Then contact your local service provider for advice on the most costeffective way of capturing data on the selected items,” says Ron K

“There may not be one single best method of metering the installation,” Klober continues. “For example, some of the smaller applications may be monitored using circuit transformers connected directly to a recording device. Others may be of such size or location as to require individual submeters with outputs feeding back to a single recording device.”

Submetering should be flexible enough to adapt to present and future needs, and must be distributed throughout facilities at each main service point and business-critical circuit, automatically metering, logging, and uploading energy and power quality information to an open database accessible by all key personnel, according to Rudolf S. v. Carolsfeld, marketing manager, industrial and institutional systems, Power Measurement Ltd.

REAKING ENERGY DATA INTO USABLE PARTS. An understanding of what to do with the information the metering system provides is important. For example, with power factor information, the submeter informs facility professionals of when the attached piece of equipment needs maintenance. By charting the power factor over time, preventive maintenance can be properly scheduled before the device becomes worn.

Through the use of submetering, says Michaels, the energy-use profile may show how much energy is used by individual pieces of equipment, such as fan systems, pump systems, cooling plants and air compressors. Once problem areas have been identified, facility professionals can plan potential upgrades. Each project should be evaluated based on the return on investment, as well as safety and environmental considerations. Specific energy usage information for the analysis may include critical loads, time of demand use, submetering schemes, emergency power loads, energy management capabilities, in-house ability to obtain accurate data and perform testing, available rate structures, and the ability to capture and classify a variety of critical power quality issues.

Load information provided by submeters can also be used to separate major loads, such as lighting, cooling and office equipment for purposes of “disaggregating loads.” This will likely require some auditing of major energy equipment’s operating schedules and kilowatt loads. The separate monitoring shows ways to reshape a facility’s energy use to yield lower prices: for example, by installing thermal storage to create cooling through cheaper off-peak power, by adding an energy management system to better control loads, or by determining where to add meters to enhance control or isolate loads that are cheaper when served by the utility. Disaggregation also allows facility professionals to work with marketers in determining how to shape the load to yield the best pricing. Finally, disaggregation makes it possible to see what type of tariff or price offering best suits present power needs (e.g., time-of-use, flat and interruptible) and switch to that tariff or request its creation.

UBMETERING TO MONITOR SHED POWER. To tie this information into a viable planning tool for facility professionals requires collecting and tabulating several pieces of information on a monthly basis. Facility professionals should, therefore, ensure that the submeter can be attached to the existing building management system or that a software program is available to automatically tabulate the data generated by the submeter.

Information gathered from submetering also can be used to off-load certain activities to nonpeak energy consumption times. For example, the start-up of high-energy pieces of equipment can be rescheduled to the early morning or late evening hours when the cost per kilowatt-hour is generally lower. Staggering start-up times for high-energy equipment can also reduce the peak demand. ID

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