Credit: Photos courtesy of Schneider Electric/Square D
To comply with the requirements of California's Title 24 energy code, which requires automatic lighting controls to help reduce lighting energy, a facility upgrade at San Francisco's Westfield shopping center uses a web-enabled control system to model the lighting zones based on need at any given time of day.
The Westfield shopping center utilizes as much daylight as can be harvested from the three-story dome and skylights scattered throughout the center.
AS THE COST OF ENERGY RISES MORE AND MORE, BUSINESSES AND CORPORATIONS ARE BECOMING INCREASINGLY aware of the amount of energy that is spent on lighting annually. New technology cannot only help reduce the amount of electricity we consume, thereby minimizing operating costs, but it also could improve the spaces we occupy, creating more pleasant work and living environments.
The following three case studies examine the conservation of lighting energy: the Westfield Centre, Mervyns Department Stores, and Ford Motor Co.'s Windsor Locks High Velocity Center. Each test case incorporated new technology to reduce the total electrical load of their respective buildings, resulting in surprising savings and lighting upgrades less expensive than one would anticipate.WESTFIELD CENTRE, SAN FRANCISCO: WEB-ENABLED LIGHTING CONTROL
The Westfield Centre in San Francisco, which opened in 2006, is a shopping center with nine floors of shops, restaurants, entertainment, and offices.
The center includes the old Emporium building built in 1896 with a restored Beaux-Arts façade and a new structure that houses both Bloomingdale's department store and a nine-screen Century Theatre. Between these two merchants is a restored three-story, 500,000-pound dome that was rebuilt after the 1906 earthquake.
Driven by the requirements of California's Title 24 energy code, which requires automatic lighting controls to help reduce lighting energy, and a desire to attract customers while highlighting the historic architecture, a lighting control system from Schneider Electric was selected—the Square D Powerlink 3000-level web-enabled system. This control system works by modeling the lighting zones based on need at any given time of day and utilizing as much daylight as can be harvested from the dome and skylights scattered throughout the shopping center.
Significant preparation went into creating a lighting scheme for the shopping center that would balance the modern and historical attributes while meeting the requirements of Title 24. The San Francisco office of Horton Lees Brogden Lighting Design (HLB), under the guidance of senior principal Angela McDonald, developed a color-coded matrix that was tailored for each of the 37 zones necessary to provide both general lighting and architectural scenes.
The operation of each lighting zone included an assessment of the total amount of light and the appropriate duration. HLB provided the engineers and building owners with recommendations for each lighting scheme throughout the Westfield Centre, taking into consideration three main time periods: opening to sunset, sunset until retail closing, and from retail closing to cinema closing.
Meeting the requirements of the 2001 version of Title 24, under which the project was completed, was a difficult task. With greater emphasis on maintaining power density below specified limits—such as retail spaces fewer than 2.2 watts per square foot and nonpublic areas, such as storage space, at fewer than .7 watts per square foot—it was a challenge for the engineers to keep the lighting loads below defined limits. The California code also mandates a two-hour maximum override for the system followed by an automatic shutoff. In the center, this override is used as a special cleaning scene customized to each floor. With the push of a button, the maintenance crew can clean floors at its convenience and after two hours, the Powerlink system takes over.
The control system components include 60 Square D Powerlink lighting panelboards located throughout the building. Twenty of the panelboards are “masters” with the remaining 40 considered “slaves.” Only two of the master panelboards contain scheduling and zone information, as these two “publish” all the information onto the system network where the slave panelboards can pull individual assignments. To configure the Square D Powerlink system, the Westfield Centre hired Eugene Gutkin, owner of Integrated Building Solutions, who provided commissioning on the complex system over several months as well as developed a graphical interface though a web browser that the shopping center's operations personnel can use to alter the lighting zones. Accessed through a computer in the administration offices, the lighting can be changed with the click of a mouse.
With this control system, the shopping center would like to achieve a minimum of 15 percent reduction in electricity in the first year of operation. It is estimated that the web-enabled aspect of the system will provide almost 10 percent in energy savings as compared with non–web-enabled systems.