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The practice of submetering—tracking energy usage past the point of the utility entrance in master-metered buildings—is increasingly common at multi-family residences and institutional, commercial and industrial facilities for many good reasons. The monitored data—starting with straight kWh consumption and expanding from there—provides owners and managers with detailed information about energy use per apartment, office, department, production line in a factory, or other breakdown. Installing submeters can provide another source of revenue in both new construction and retrofits.
The ability to monitor energy closely can be useful for internal billing or for passing along energy costs directly to tenants or departments in an equitable way. It is a lot fairer than relying on billing by square footage, hours of occupancy, a straight-across-the-board energy surcharge or other factor that does not account for variations in usage. When faced with paying for actual energy used, many tenants themselves may choose to use energy more prudently. Submeters are also helpful in allocating common area management energy costs, such as hallway, lobby and outdoor lighting and pinpointing and prioritizing areas where replacing obsolete or inefficient electrical installations makes the most sense.
Because utilities may vary energy rates throughout the day, monitoring energy usage in industrial and commercial facilities by department or equipment load can help management reduce cost for electrical energy. For instance, management may choose to time shift the running of non-critical loads and schedule energy-gulping assembly line functions at times that, overall, will keep utility rates as low as possible. And commercial and retail facilities may use the data to curtail hours of display lighting or signage as well as HVAC loads to make the loads more consistent throughout the day. Indeed, some utilities have peak shaving incentives that reward customers who keep demand during peak periods below a certain level with a lower energy rate for the whole month.
Submetering can also be used to spot irregularities in billing that can indicate malfunction of electrical or electronic equipment and to detect trends that affect electrical energy costs.
Widely available for single phase or three phase electrical circuits, submeters generally feature local viewing via a liquid crystal display (LCD) that provides easy access to real time and, perhaps, historical data. Data logging meters will collect and store information for 30 days or more.
Meters are available that can be read remotely as well as (though in some cases instead of) onsite, providing analytic use of that energy "intelligence." Data is sent over telephone lines or radio power lines or over an Ethernet or the Internet. If the meters are connected to a remote energy management system, interested parties who have access to the appropriate wireless meter reading software can download and analyze the readings at will. And for retrofit installations where new communication wiring is not feasible or desirable, meters are available that can provide standard power line communications of readings.
Whether used for cost accountability or cost allocation, sub metering of electrical costs can be a win/win/win situation. The end-user has the ability to control costs to some extent enacting conservation measures they can live with. The owner, by separating the lease from the energy billing, minimizes risk of dramatic fluctuations in energy costs, with higher pricing during peak (and likely popular) periods. And the utility company, historically strapped for resources, enjoys a little more cushion and a bit less stress when customers are aware of their energy expenditures and actively conserve energy.
Electrical distributors and electrical contractors who become active in supplying and installing sub meters, respectively, can likely catch a windfall from it all.
author: By William & Patti Feldman