Approximately 50% of the Bank of America Center is electrically submetered, which is saving over $1 million in annual energy costs
Just two blocks down California Street from San Francisco's historical Chinatown and at the entrance to the city's bustling financial district rises the 52-story Bank of America Center. Operated by Shorenstein Realty Services, this high-rise not only houses Bank of America, but a "Who's Who" of the city's financial investment community and some 5,000 to 7,000 office workers.
For many tenants at 555 California Street, operations are 24/7, with computer networks, file servers, and other systems and equipment requiring uninterruptible power supplies and supplementary air conditioning. These special requirements place increased demands on the building's energy infrastructure and routinely outstrip the typical 3 kW/sq.ft. energy allocation built into the tenant lease costs. Since this energy allocation is based on daylight hours of operation (6:00am to 6:00pm, Monday through Friday and five hours on Saturday in some cases), it is not uncommon for tenants to consume two to three times their baseline energy allocation.
Up until seven years ago, energy cost recovery was based on estimated electrical usage and negotiations with the tenants. That all began to change when an electrical energy submetering system was installed.
As part of new lease agreements starting in 1993, tenants agreed to install electric submeters so they could be fairly and accurately assessed for excess energy consumption. What began with a few submeters has now grown into a network of more than 120 submeters that measure and record energy usage in more than 50% of the building's nearly two million square feet of office space. Plans call for the remaining space in the building to be submetered as well, as new tenants move in or as new leases are negotiated.
According to Sean Murtagh, assistant chief engineer and Life Safety director, "We started this program with the installation of a few meters and, little by little, we expanded to where we are today.
"In the early days of the program we would go from floor to floor and manually record the data from each submeter. But the program really took off once we installed the automatic meter reading hardware and software," Murtagh adds.
The automatic meter reading (AMR) system consists of several communication interface devices that accept data from numerous submeters, typically located in the electrical room on each floor. The interface units (IDRs) connect in serial fashion over a two-wire communications link to a PC in the engineering offices in the basement. Custom software allows facility managers to custom-tailor billing reports to each tenant, with monitoring capability extending to an almost unlimited number of data points due to the modularity of the hardware and software system.
Murtagh explains the ease of installation: "A crew ran a backbone riser for the communications loop. Then slowly, we installed the meters. Then I began to install the interface units with the communication connectors, making connection with each submeter. The individual submeters are easy to install. The split-core current sensor snaps around the conductors and the measuring unit can be installed just about anywhere there is space, not just next to the circuit being monitored or in an electrical room."
At the computer end, Murtagh was responsible for setting up and operating the system software. "I'm not a computer expert, but I was able to get this system up and running with the thorough support of the vendor's engineering staff," he says.
"With the AMR system, we can automatically create energy bills for each tenant. The bills itemize usage for each submetered area and make adjustments for the base energy usage allotment."
With the electric energy submetering system in place, Shorenstein was able to recover over $1,000,000 in excess energy usage last year, and is realizing overall savings in energy costs/consumption of approximately 30%. Murtagh is quick to give credit for the success to the foresight of his boss, Chief Engineer Bob Clay.
"Bob is the one who got the ball rolling," notes Murtagh. "Now many of our 10 other Shorenstein properties (compromised of 16 high-rises) in the San Francisco/Oakland area, as well as properties in New York City, Miami, Chicago, Houston, Phoenix, New Orleans and elsewhere, are looking to add or expand existing submetering systems."
Bob Clay says the return on investment for this project could be measured in "days, not years." He notes, "Our only real investment was in a few thousand dollars worth of PC equipment. The submetering hardware costs are borne by each tenant."
The AMR system has added other benefits in addition to energy cost recovery. It also allows for analysis of building energy load profiles and energy consumption aggregation information. This data is valuable for planning improviements to the building's distribution system and is a key resource in negotiating future energy contracts with both tenants and utility providers.
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