METERING TECHNOLOGY
Submetering: Increased Interest in a Low-Cost Technology
By Don Millstein
The problems of rising electricity costs, increasing power consumption and supply unpredictability in the U.S. are sending palpable warning signals to Canada. According to a May 2001 update to the second edition of the Retail Energy Deregulation Index 2001 (RED Index), Canada already suffers from constrained power supply in the Pacific Northwest.[1]
Additionally, provinces are keeping a wary eye on California's rolling blackouts and skyrocketing electricity prices while grappling with their own experiments in restructuring. Alberta's electricity prices quadrupled last year and Ontario is determined to avoid a similar fate. On the bright side, the unstable energy environment in California provides countries like Canada with not only a valuable lesson on avoiding deregulation pitfalls but also on effectively implementing cost-saving options.
Energy Probe, a Canadian consumer and environmental advocacy group, estimates that Ontario's electricity prices will rise at least 20 per cent in two years and utility experts expect electricity bills in Ontario to more than double.[2] Predictions like these are causing Canadian businesses to rethink how they manage their energy usage, especially when considering the U.S. energy situation.
This emphasis on energy conservation to lower electricity bills has led to a surge in interest in submetering technology.
Although it has existed for some time, submetering technology is drawing renewed attention from energy-conscious regions. In June 2001, for instance, California sponsored a program to install more than 3,400 meters in Los Angeles businesses to help with the areas' energy crisis. Indeed, utility and facility managers, building engineers, energy consultants and service providers the world over are interested in submeters for being cost-effective, easy to install and for having a proven track record for lowering energy bills. This sophisticated technology succeeds by gathering and delivering real-time energy usage data to facility operators, allowing them to take proactive measures to significantly reduce bottom line costs.
Energy Management
The combination of submetering equipment and software is used to monitor a facility's energy via comprehensive energy profiling - information needed to determine a facility's energy demand and usage levels. The information garnered from tracking electricity usage this way is then used for peak shaving, load shedding, aggregation and other measures, that lead to lowered energy bills. A submetering device provides the energy manager with energy consumption data showing how slices of the "energy pie" are distributed to the various departments, tenants, or processes within the building or facility. From here, submetering lets the consumer define energy usage all the way down to a 15A branch circuit, if necessary. Such precise metering happens from tracking demand (kW) and usage (kWh) to provide aggregate data. With the appropriate software, the user can manipulate and display this raw information on a centralized or remote Windows-based PC operator interface.
Automatic Meter Reading (AMR) capability allows the submetering system to be read anywhere, anytime, and in any weather from the convenience of a computer. Time-of-use graphs and charts give the user the data necessary for real-time pricing, event analysis, Demand Side Management (DSM) programs and Energy Management System (EMS) performance analyses. For added flexibility and convenience, energy managers can choose to access submetering information on-line. A submetering company, for example, can offer a service that helps users track and analyze their electrical consumption and demand by logging on to the Internet. The energy data is acquired from any meter with a pulse output, such as utility meters and submeters. The metering data is collected by a hardware interface and sent via cellular or telephone modem to the server. The information is posted daily to the subscriber's password-protected folder where it may be accessed directly by a PC (Fig. 1). By using this type of service, users can access the following energy profiles over the Internet:
- Statistical analysis of energy consumption
- Energy analysis by: 15, 30, 60 minute intervals
- Daily, M-T-D, Y-T-D
- Weather, Degree Days
- Budgets
- KWH, KW, $
Lowering Energy Bills
Companies like E-MON Corpora-tion, which has customers ranging from multi-tenant apartment buildings, government facilities, sky rises and the personal estate of Microsoft founder Bill Gates, has seen its customers enjoy significant energy savings due to submetering installations (fig. 2). Demand in submetering products is growing concurrently with California's energy crisis and with a global concern for energy conservation. For example, many multi-tenant and multi-building facilities are using electric submeters and Automatic Meter Reading (AMR) equipment for billing and allocation, cost center analysis, energy use verification and demand control and analysis to save energy, and money.
Studies have shown that 7-15 per cent cost savings can be achieved by simply allocating electricity to the proper user. Not only is this method more equitable than lumping various users or departments onto one bill, it gives facility managers a way to view and control how energy is allocated at their sites. If governmental or company incentives are involved, individual energy users are empowered to lower their own usage and reap financial benefits, while skirting penalties for another tenant's or co-worker's poor energy habits. Typical facilities applying submetering for cost allocation measures, include:
- Government facilities
- Hospitals
- Airports
- Schools and universities
- Multifamily dwellings
- Shopping centers
- Industrial facilities
- Commercial Offices
As a system "watchdog," the submetering base informs the user of any changes in energy usage patterns. It can also act as a power quality meter to draw attention to possible anomalies in expected electrical system performance. At the enterprise level, submetering allows facility managers to accurately assess energy usage by specific areas to highlight energy efficiency opportunities and to implement electrical demand "shedding" or "rolling". In plant floor settings, submetering allows engineers to precisely evaluate the performance of individual machinery and processes, as well as to identify inefficiencies and opportunities to increase productivity.
Additionally, besides allocating or dividing and properly allotting energy costs according to usage, submeters can be used for aggregation, or combining loads from various sites to negotiate rates with energy providers. Savings on such aggregated demand can average up to 20 per cent -- especially in applications where loads are diverse (where peak demand is generated at different times) as in hospitals, schools, and manufacturing plants that may have more than one location.
Ease of Installation
Submeters are installed after the master meter in a building or facility. Besides being low-cost, submeters are safe since electricians don't even need to power down the load to install. Additionally, the meters facilitate electricity monitoring without doing major changes inside a commercial or residential building (Fig. 3.). Indeed, installation is simply a matter of hooking three current sensors around the electrical feeds being measured. And, the meter can be mounted anywhere.
In this way, the contractor can quickly turn a very profitable installation in a fraction of the time needed to install an older style socket-based meter. All told, the time and cost to install an electronic submeter typically runs less than 25 per cent of having the utility install a dedicated meter on the same circuit.
Contemporary electronic submeters eliminate the need for meter pans and current transformer (CT) cabinets, and are much easier and flexible to install. Their compact size allows installation in areas too cramped for previous metering methods (Fig. 4).
It's not uncommon to install 40 or more electronic submeters in the same amount of space occupied by fewer than half a dozen electromechanical type submeters. Since feedthrough wiring is not required, subpanels aren't necessary for proper monitoring. In fact, multiple meters can be used to monitor individual circuits in a breaker panel without having to rewire the panel.
The Bottom Line
Applied in a diversity of applications, submeters are allowing buildings, institutions and utilities to realize savings of up to tens of thousands of dollars per month, depending on the type of facility being profiled. The reason? Advanced metering equipment puts knowledge and control in the hands of facility operators. By comparing historical energy usage with current trends, these managers can identify energy savings opportunities guaranteeing the largest payback.
Because data and budget numbers play a major role in determining the best energy conservation measures to undertake, the information gathered from PC and web-based software and meters is an invaluable resource.
Submeters are a cost-effective, tried-and-true method for lowering energy costs -- in a time when energy savings can mean business survival.
References
- The Red Index report is issued by CAEM (Center for the Advance-ment of Energy Markets) nonprofit Washington-based think tank whose mission is to promote an effective transition from the monopoly to the competitive model of regulation.
- "Power Crunch," by Kimberley Noble. Maclean's, April 23, 2001. Section: Special Report; Business; Pg. 42.
- "L.A. Businesses to Get ÔReal-Time' Electricity Meters." Los Angeles Times, Friday, June 8, 2001, C2.
Don Millstein is the president of E-MON Corporation. ET
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