Submetering can measure energy use more accurately in shopping centers
With continuously climbing utility rates, building owners and operators are constantly seeking ways to rim operating costs to relieve pressure from the bottom line. As pass-through recipients, retail tenants are equally concerned about minimizing energy use and maximizing efficiency in the face of utility bills over which they have traditionally had little control.
Electric submeters have emerged over the last quarter century to change all that. As a way to more accurately gauge actual tenant power consumption, submeters offer an extremely cost-effective way to fairly and accurately determine energy use with a level of granularity unmatched by the master utility meter at the main electrical service entrance. When installed, submeters add value to commercial real estate properties — whether designed in by the architect or retrofitted — precisely because facility energy snapshots of individual energy usage appeal to everyone, from owners and operators to existing and prospective tenants.
Widespread use of submetering continues to gain momentum, as cost-consious building owners and operators discover their value for tracking energy demand and consumption of specific users or items of equipment all the way down to a single circuit.
Monitoring individual electrical usage
Widespread use of submetering continues to gain momentum, as cost-conscious building owners and operators discover their value for tracking energy demand and consumption of specific users or items of equipment all the way down to a single circuit. Installed on the building side of the utility master meter, electric submeters are accurate, highly effective tools for any number of uses including:
- Cost recovery and allocation
- Load profiling
- Tenant billing
- Energy management
- Green building initiatives
- Measurement & verification for proving compliance with energy initiatives
- Multi-site load aggregation and real-time historical monitoring of energy consumption patterns for negotiating lower energy rates.
Submeters at a glance
All submeters are not created equal. OF the three main submeter types shown in the table below, the first two, feed-through and current transformer (CT)-based, are socket-type meters. CT-style socket meters are used with loads of 400A and above. In commercial applications, they may be specified but will take up a lot of space in the electrical room due to the need for CT cabinets along with the meter bases. The extra space required eats into the available rental square footage, which is undesirable in the commercial marketplace. Another major disadvantage in many jurisdictions—socket meters are not UL listed. The third type is the electronic submeter, a non-socket device that provides clear advantages over the previous two as shown.
A key advantage of the electric 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 and more profitable install for the electrical contractor.
Advanced meter function
In the past years, submeter manufacturers have responded to the growing need for more sophisticated energy profiling data by developing products with advanced meter functions that provide more useful data than standard utility meters. Essential for supporting EPACT, Demand Response and other emerging energy initiatives, submeter-based automatic meter reading systems can combine all of the facility's utility data — electric, gas, water, steam, etc. — into a single location to show how, when and where the facility is using energy. This information is communicated back to a central monitoring point via the facility's existing ethernet LAN infrastructure, Modbus protocol, RF or other communications medium.
Multi-facility metering allows energy managers to combine or aggregate the energy demand and usage of multiple sites into a single virtual meter to generate a single corporate billing statement. This ability is especially useful in deregulated markets for negotiating lower energy costs with energy providers.
Wireless submetering systems are appearing in the multi-user residential and commercial facility applications. These FCC-approved devices operate on the 915 MHz (100mW) frequency band and are ideal for applications in which the meter must reside in the occupant's space. In retrofit scenarios, the new wireless meters are quickly and easily installed, unobtrusive to the tenant, and provide metered data to the AMR system via mesh communications networks that transmit more effectively through dense building materials than 2.4 GHz systems. Another advantage of mesh communications in the retail environment is that, should a meter be added or removed, the network automatically creates (or repairs) a path to the central host — all without tenant involvement.
Submetering green buildings
Green buildings and sustainability refer to the practice of optimizing building efficiency by using less energy, water and materials, and by reducing the impact of buildings on health and the environment through better design, construction, operation and maintenance. Submeters can contribute directly to the certification of facilities under major green building initiatives — such as EPACT/EISA and LEED — that are rapidly impacting the commercial, industrial and institutional building sectors. Retail operations within these areas will likewise be impacted by emerging energy guidelines.
In service for more than 25 years, submeters are used in literally hundreds of thousands of facilities around the world. Easily installed without powering down the measured load, submeters provide insight into energy management that leads to cost savings, greater energy efficiency and a higher level of conservation awareness. Whether designed in by the architect or retrofitted by the owner, submeters not only increase tenant satisfaction and retention, but add value to the commercial property itself.
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