Submetering Project Earns 5-Month Payback at Phoenix Plaza - Phoenix, AZ
The installation of an electrical submetering system is helping buildings managers at Phoenix Plaza — a pair of multi-tenant, high-rise office buildings— more accurately track and bill energy use, resulting in a payback for the project of about five months.
Phoenix Plaza consists of two, 21-story office buildings housing 34 different offices, a retail center and a parking garage. The buildings are owned by Shorenstein & Co., a San Francisco-based building management firm.
The cost for the submeter installation, about $75,000, will be recovered quickly because of two factors. By billing tenants for their actual energy use, energy managers are able to reduce operating costs by about 25 cents per square foot, according to Bill Wilson, chief engineer. With submetered office space in the two towers totalling 800,000 square feet, annual savings could reach about $200,000. Also, the closer monitoring of energy use has led to an increase in energy conservation measures by tenants.
The project was motivated by the need to make billing more fair for the facility's tenants. Before the installation, tenants signed leases that stipulated energy payments based on a flat rate per square foot. If a tenant used more energy than the preset cost, the difference would have to be made up by other tenants. Some tenants exceeded typical energy use by using power after normal business hours or having more people or equiment in a space than was recommended.
'Right now we are trying to make it fair to all tenants, to the people who are the larger users. IBM—I mean, they're a computer company. They have a LAN room that has computers from top to bottom. They also have alot of air conditioning," said Bob Hanson, a Phoenix Plaza engineer and the main system operator.
"Ad all the money that we recover gets put into the 'kitty,' operating costs go down, and the other tenants benefit," added Roy Bardzik, assistant chief engineer for Phoenix Plaza. "People who are using power are paying for it now. It's not being spread equally among everybody. Its more fair to the little guy."
Current sensors on each floor monitor and send energy information to the facility's engineering office, where the data is collected and recorded by submeters from E-Mon. Building engineers track a total of 80 points, which are collected in multiple meter unit (MMU) cabinets. The facility has four, eight-meter MMUs and two 25-meter MMUs.
IDR data accumulators, also by E-Mon, were placed inside the MMUs to read the meters. This data is transferred to a PC, where the data is analyzed and bills are prepared using the company's automatic meter reading software.
The equipment was installed by local company Hyde Electric. The entire project, completed in January 1998, took about a year to finish. The retrofit began on the floors with the larger tenants, then moved to the smaller tenants.
"The hardest part was when we first started. I had to go to every single floor and map out circuits, stuff like that," Bardzik said.
Energy managers have noticed that tenants are more energy conscious since the submetering began, a trend that could lead to even more energy savings, Bardzik said.
The savings that are expected from the submetering will allow energy managers to focus their time on other areas, such as additional capital repairs and improvements.
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