Submetering for Real-World Energy Savings
Increasingly, state-of-the-art commercial properties are using submeters for the energy measurement and verification needed to obtain LEED certification points in Core & Shell, Existing Buildings, New Construction, Commercial Interiors and other areas. This article describes what submeters do and how they can help facility managers cut costs in today's sustainable facility market.
Since their introduction in the early 1980's, solid-state electronic kWh submeters have gained widespread acceptance and are now installed worldwide for a broad range of energy monitoring and management applications in skyscrapers, shopping centers, airports, factories, office buildings, apartment complexes, industrial, governmental and educational facilities.
Monitoring Individual Electrical Usage
As a highly accurate and scalable way to gauge actual power consumption (kWh) and demand (kW), electric submeters provide an extremely cost-effective way to fairly and accurately profile and manage precious energy resources with a level of granularity unmatched by the master utility meter at the main electrical service entrance. Typical uses include:
- Cost allocation for tenant and departmental billing
- Usage analysis and peak demand identification
- Common Area Management
- Interval data recording in 15- or 30-minute time intervals
- Time-of-use metering of electricity, gas, water, steam BTUs and other energy sources
- Measurement, verification and benchmarking for energy initiatives, including LEED Energy & Atmosphere (EA) and Water Efficiency (WE) credits
- Load comparisons
- Threshold alarming and notification
- Multi-site load aggregation and real-time historical monitoring of energy consumption patterns for negotiating lower energy rates
Advanced Metering Increases Value for the User
In the past, meter data was personally gathered by onsite "sneaker reads." Later, telephone modems greatly improved cost-efficiency and throughput. This was followed by sending data via Ethernet, wireless (RF) link, satellite, power line carrier (PLC) and other technologies. All of these methods are still in use to some extent, however, the data itself is more complex and is now being used to drill down even deeper into the facility energy envelope in an attempt to get a better handle on operating costs.
Manufacturers of energy monitoring products and services have responded to the challenge by introducing improved metering products with new communication options like wireless mesh networking and compatibility with Modbus, BACnet, LonWorks, IP and other protocols that continue to drive the technology toward greater sophistication and value for the user.
Submetering for LEED v3 Credits
LEED v3's energy section offers some of the building assessment system's most targeted guidelines for decreasing energy consumption and increasing alternative energy use. LEED v3 also provides guidance on commissioning, so that facility executives can be sure their systems are functioning at peak efficiency. The backbone of the measurement and verification (M & V) process required for LEED certification at every level is the electric submeter. The primary building performance category in which submetering plays a key role is the Energy & Atmosphere (EA) subset that runs through most, if not all, major assessment categories, including Commercial Interiors (CI), Core & Shell (CS), Existing Buildings-Operation & Maintenance (EBOM), New Construction (NC) and Schools.
Meter Dashboards Increase Energy Awareness
Internet-enabled energy monitoring and data presentment dashboards are gaining traction in the facility environment for displaying kWh, kW, peak demand, power factor and other energy measurements in real time, and historically, while also displaying the facility's "carbon footprint." This allows facility occupants to monitor their building's carbon dioxide (CO2), sulfer dioxide (SO2) and nitrous oxide (NOx) emissions-while at the same time observing estimated energy conservation measures needed to compensate for the displayed levels.
Submeters Drive Real-World Facility Savings
Submeters are making valuable, quantifiable contributions to bottom lines across the facility landscape. In San Francisco, for example, about half of the 52 story Bank of America Building was submetered after energy managers learned that tenants' 3 kW/sq. ft. energy allowance was being exceeded by as much as 300%. More than 120 submeters were installed with the result that the assistant chief engineer estimated that the property owner was able to recover about $1 million in excess energy usage in the first year of operation alone. He further stated that the cost of the submetering hardware and software in this application resulted in an ROI of days, not years, complemented by energy usage and cost savings of 30% per year. As a result of this experience, this leading nationwide property management company is evaluating submeters for its other properties around the country.
Another example, Los Angeles Air Force Base, is running 36 submeters in 14 buildings on the 150-acre base. As a result of submetering, the base energy manager estimates that energy consumption has decreased more than 27% from his earlier base line. Also, base utility expenses dropped 23% during a time when rates actually increased 4.5%. As a result of the energy manager's submetering-based conservation successes, he received the Air Force Material Command's Energy Award for that year.
In Washington, D.C. the Smithsonian Institution's Energy Management Group estimates that the 11 museum facilities in the Capital Mall were able to bill back $1.7M of their 2003 energy costs to lease tenants that otherwise would have been paid with Federal tax dollars. The lead technician estimated that the figure would rise to $2M the following year due to rising utility rates and the opening of a new facility. According to this Energy Management Group technician, the $100K investment in metering hardware and software was paid for only three months after the first quarterly utility billing cycle.
Submetering the Bottom Line
Metering provides the raw data for energy profiling, but data collection is only the front end of the process. Until the raw data is imported into software and manipulated for cost allocation, billing, load shedding, rate negotiations and a host of other uses, it has limited practical value. Submetering hardware and software systems help facility owners and operators work smarter, not harder, to acquire, analyze and convert even the most sophisticated energy profile data into useful information for cutting costs, using precious energy resources more efficiently and improving the facility's bottom line.
The old energy adage "you can't manage what you don't measure" is particularly appropriate to today's energy-conscious facility and is also an extremely effective door-opener for any architect and engineering firm, contractor or distributor desiring to promote the easily demonstrated benefits of submetering to his valued customer.
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