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By Keith Pierce, vertical sales manager, and Rick Leeds, vertical marketing manager, Osram Sylvania
A majority of retailers are unsatisfied with their lighting, according to a 2012 survey of 87 retailers, including supermarkets, conducted by the California Lighting Technology Center (CLTC). Fifty-six percent of respondents were either “somewhat unsatisfied” (40 percent) or “not at all satisfied” (16 percent). While upgrading an existing lighting system typically focuses on reducing operating costs, with typical payback criteria of 1-2 years, a majority of retailers believed a lighting upgrade should increase sales (47 percent) or both (37 percent).
As a design tool, light has a proven influence on visibility, wayfinding, directing visual attention, and overall general perception of store brand identity, product quality and price points. As a result, lighting plays an important part in supporting sales. So much so that it is often called the “silent salesperson” in the retail segment.
The first step in any lighting upgrade, therefore, is to evaluate the effectiveness of the existing lighting scheme and what actions may be taken to optimize it. Then the requirements of a new lighting system may be specified that will achieve the business goals before determining how to minimize the energy and maintenance cost.
Ambient, Accent and Task
Good lighting design practice encompasses a range of qualitative considerations that go far beyond calculating light levels. At a minimum, the lighting system should provide good visibility without glare, flicker or excessive shadows. Beyond that, where to direct light is as important as its quantity. The lighting design should be layered in three primary components—ambient lighting, accent lighting and task lighting. Accent lighting is particularly important in today's grocery store designs. Using zones of higher brightness creates points of interest that draw attention to key merchandise in specialty departments selling such items as produce, deli, baked goods, flowers and wine. Well-placed accent lighting can create an interesting and engaging atmosphere. The best designs have a high degree of flexibility, often using adjustable mono-points, or track lighting, to accommodate frequent changes in size and location of displays. Remember that illumination on vertical surfaces, such as labels and food packaging on shelves, is often far more critical for a satisfying shopping experience than on horizontal surfaces.
Color is another critical aspect of effective lighting, particularly in retail environments such as grocery stores, where the application requires accurate and appetizing rendering of food. The primary metrics are color rendering index (CRI) and color temperature (measured in Kelvin). In areas where color accuracy is critical, a very high CRI rating is important. Color temperature influences perception of a space as “warm” or “cool,” with warm light sources (< 3000K) emphasizing colors such as reds and oranges; cool sources (> 4000K) emphasizing blues and greens; and neutral sources feeling very balanced. If available, daylight is an excellent source of light with premium color quality, though it must be carefully controlled within the scheme of the design.
Assuming that the lighting system is fulfilling its role as the silent salesperson, how can the right light be delivered at the lowest operating cost?
The CLTC survey determined that 76 percent of respondents were using incandescent, 51 percent halogen, 61 percent linear fluorescent, 17 percent compact fluorescent, 9 percent light-emitting diode (LED) and 6 percent “other,” such as ceramic metal halide. Incandescent and halogen lamps are excellent sources for accent lighting but produce heat that can be detrimental to fresh produce and adversely impact HVAC loads. These lamps are also inefficient by today’s codes and standards, and have relatively short service life. Compact fluorescent is a highly efficient alternative to incandescent, but is best used in ambient lighting or decorative luminaires where a diffuse distribution of light is desired.
A simple upgrade in most accent lighting and downlighting applications is to replace incandescent, halogen and compact fluorescent sources with LED replacement lamps. LED technology has come a long way in a short time, with the best-performing products providing good lighting for a fraction of the energy cost along with long service life and no radiated heat or ultraviolet output in the directed beam. Prices have been falling steadily, resulting in good return on investment opportunities. When choosing any light source that replaces incandescent and halogen, make sure it offers suitable color quality, paying particular attention to how well the light source renders saturated reds typically found in grocery store merchandise (e.g., meats, produce, flowers, etc.). For LED sources used to highlight these premium goods, a high deep-red content is recommended, characterized by an R9 value greater than 50 (a metric related to the CRI metric mentioned earlier). In areas with very high ceilings or where high illumination contrast is desired, ceramic metal halide sources may be a good option, providing a great deal of light in a small package. When in doubt, seeing is believing; request samples of the light sources and observe how well they render colors in a mock-up.
Linear fluorescent lighting typically provides ambient lighting throughout the store, as well as in refrigerated display cases. Here there are two options to consider as part of a retrofit scheme. The first is to retrofit existing luminaires or install entirely new luminaires using the latest T8 or T5 lamps and ballasts. Next-generation T8 systems comply with the latest energy legislation and can reduce energy costs resulting in a good return on investment even if T8 lighting is already installed. The other option, of course, is new LED luminaires or upgrading existing fluorescent luminaires with LED technology using retrofit kits. Within the past two years, LEDs have entered the general lighting market in dramatic fashion, with numerous choices providing the benefits of high efficiency and long service life. As LED is a relatively young technology, however, be aware that the market is showing a wide range of performance among products, and according to Department of Energy testing, not all performance claims are accurate. When choosing LED, be sure to work with a reputable manufacturer that can back its claims based on standardized testing.
Don't forget niche and outdoor areas where new lighting choices can also make a difference. LED lighting offers excellent solutions for loading docks, parking lots, entryway canopies, exterior walls, walk-in coolers and signage.
Once there is a good lighting design realized by equipment that performs well for a lower energy and maintenance cost, consider lighting controls. Choices range from simple automatic shutoff and dimming to color temperature tuning and lighting management systems that produce information useful for energy analysis. Lighting control promises to be the next revolution in sustainable energy conservation, and works well with LED and fluorescent lighting, with a new generation of intelligent, wireless, luminaire-integrated sensors and controls simplifying installation and commissioning. Daylight harvesting strategies may be implemented in areas with perimeter windows or skylights. Illumination levels may be reduced in the evenings when contrast can be minimized versus the dark night sky.
For all of the above options that save energy, from lighting to controls, good lighting rebates are available from utilities and energy efficiency organizations. Rebates are available in most states and can significantly reduce the cost of new lighting, improving ROI.
The current revolution in the lighting industry—focused on energy efficiency, service life and controllability—may offer dramatic new opportunities for grocery stores to optimize the lighting so that it helps sell products and satisfy customer expectations, for the lowest energy and maintenance cost.