Surface Lot Lighting
The customer's shopping experience begins in the parking lot. If it is not safe and secure, especially at night, consumers will not stop, park or shop. That's why major retailers establish strict specifications and monitor the status of their parking lot light levels to ensure that nothing prevents potential shoppers from entering their stores. Target Corp. is the industry leader in this effort.
Target established a corporate policy to maintain standards for light levels for its stores' main parking, peripheral parking and front-drive areas. As part of its store maintenance program, Target periodically evaluates the light levels of each of its store location's parking lots. That's why when Target believed parking lot light levels at its Hollister, CA, location were not meeting corporate standards, it contacted Site Photometrics in Columbia, MD, to implement a luminance survey to measure light intensities from fixtures at various locations within the site area.
In May 2003, Site Photometrics (SP) evaluated the electrical system, light poles, luminaires, lamps, poles and pole foundations in the 200-space parking lot at Target's Hollister location. Its study found that the existing lighting system included 1,000-watt, 277V Cooper Galleria large-area lighting luminaires with high-pressure sodium (HPS) lamps, and Type AR (vertical symmetric) optics with a bronze finish, mounted on 39-foot round tapered steel poles. More important, Site Photometrics quickly determined that only 55 percent of the main parking lot area achieved the corporation's 3.0 foot-candle standard, while 95 percent of the peripheral parking lot areas attained the 2.0 foot-candle requirement. In addition, about 85 percent of the front-drive areas achieved Target's 5.0 foot-candle standard. SP also found that one of the poles needed to be replaced.
In July 2003, Site Photometrics provided three solutions that addressed both lighting requirements and budget considerations. Each came with a computer model and guaranteed lighting performance. All three also included changing the lighting source from HPS to metal halide.
"When we complete an assessment and make a recommendation, " said Jerome Morstein, principal of SP, "we try to use the existing infrastructure as much as possible to minimize expenses for our customers. For instance, we found that we could still use the electrical systems and all but one of the light poles at Target's Hollister location."
While trying to minimize expenses and changes to infrastructure, SP did recommend that Target change their light source. "We have found, and retailers and developers agree, that metal halide provides a better quality of light, compared to high-pressure sodium," said Morstein. "Metal halide provides white light, compared to the yellow light offered by high-pressure sodium. Although both light sources can have the same foot-candles, it is easier to distinguish dark color under white light. That is important when you are looking for a gray, blue or black car in a congested parking lot at night."
Target Ventures into a Variety of Metal Halide Lighting Solutions
For all of their projects, Site Photometrics specifies Uni-Form pulse-start metal halide lamps from Venture Lighting, the leading developer of metal halide lighting technology. Morstein said: "We have tested the lamps and have found that they meet our tight specifications. The combination of Venture's lamps and ballasts ensures superior lumen maintenance, excellent lamp color uniformity, faster warm-up times and a high overall system efficiency."
SP's first solution to improving the lighting in the Hollister parking lot was to continue using the existing Cooper fixtures while changing the light source from HPS to metal halide lamps. The results of the change would have little effect on the foot-candle levels, but would improve the overall visibility in the parking lot.
Its second solution involved switching the fixtures to two and three Gardco HT19 1000-watt/480V metal halide luminaries on each of the existing light poles. This increased the percentage of the main parking lot area meeting the 3.0 foot-candle standard from 55 percent to 65 percent. However, only 65 percent of the main drive area would meet the 5.0 foot-candle standard.