BUILDINGS - Smarter Facilities Management


‘Work Smarter’ With Submeters

Proven Technology Shows How and Where to Cut Energy Costs


A Cool Million in Savings

Shorenstein Realty Services has used submeters for several years to realize significant energy savings at several of its flagship properties, one of which is the Bank of America world headquarters at 555 California Street in San Francisco.

When increasing 24/7 tenant operations began to intensify demands on the building’s energy infrastructure, facility engineers needed a way to accurately track excess energy usage by tenant, who in many cases consumed two to three times their baseline energy allocation of 3kW per square foot. The guesswork began to change with the installation of an electrical submetering system from E-MON LP.

The automatic meter reading (AMR) system consists of several communication interfaces that accept data from numerous submeters linked to a PC in the engineering office. The PC software, also provided by E-MON, allows facility managers to custom-tailor billing reports to each individual tenant, with monitoring capability extending to an almost unlimited number of data points – thanks to the modularity of the hardware and software system.

Rising fuel costs have made energy resource management more important than ever before, but the kind of profiling needed by today’s building manager is simply not possible using the standard socket-based utility meter found at the main electrical service entrance. That’s why electric submeters have grown in use as first-level data-gathering tools that can literally save thousands of dollars in reduced energy costs, through: automatic meter reading (AMR) of electricity, water, gas, steam, and other energy sources; time of use monitoring of energy consumption patterns; multi-site and submetered load aggregation; usage analysis and identification of peak demand; and energy usage for cost allocation, tenant billing, and more.

Submetering Hardware

Electric submeters are installed after the facility master meter and are used to track the energy use of a specific location, user, or circuit. Installation of the preferred solid-state type submeter simply requires three split-core current sensors around the electrical feeds being measured in addition to the voltage input. The data is sent to the host computer from the meter via RS485 utilizing inexpensive 4-conductor phone cable. Communication wiring can be run up to 4,000 feet in total length. Data may be sent via modem or transmitted using standard RF technology.

The submetered energy data is date/time stamped in five- or 15-minute intervals for up to 36 days. Recently introduced communications interfaces allow AMR hardware elements to operate with popular cellular services such as Sprint, Verizon, Voicestream, and other communications options. Once the data is collected on the host’s hard drive, it may be manipulated in software to produce itemized utility bills, generate load and usage profiles, customize spreadsheets, and create graphical charts and databases and other data analysis and reporting functions.

LAN-based AMR

The pervasive use of local area networks (LAN) in campus environments, multi-facility commercial, industrial, and residential sites, creates new energy monitoring opportunities. Using the existing communications backbone eliminates the need for a modem and telephone line back to the central monitoring location, and allows a full-featured Ethernet-based distributed submetering network to be installed quickly and inexpensively. Hardware is available for star and bus topology Ethernet, as well as Fast Ethernet and fiber media, thus extending submetering’s usefulness to any Ethernet medium.

Online Monitoring

The Internet may now be used to track and analyze “big picture” electrical consumption (kWh) and demand (kW) – from a single circuit in one facility, to multiple sites around the world. The metered data is transmitted to a data accumulator or profiler and sent via modem to an online server operated by an RBC (read, bill, & collect) or other third-party energy monitoring service, which posts the data to the subscriber’s password-protected folder. The data may then be accessed using any standard Internet browser.

Don Millstein is president at E-MON LP (, Langhorne, PA.


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