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archived articles Taking the Heat
Out of Retail It's is easier to save a dollar than it is to make a dollar. Therefore, using non-energy-efficient lighting systems in retail applications just doesn't make "cents." Think about it: if you can save $1,000 dollars a year by using energy-efficient lighting products, and the store's profit margin is 10%, then the store would have to increase sales by $10,000 in the first year and maintain that increase year after year to make the same profit. Don't overlook that by reducing the energy consumption of the lighting system you are also reducing the heat that the mechanical system has to remove from the space. The estimates that I have heard is that for every 4 watts that are saved from the lighting system 1 watt is saved in the mechanical system. An often overlooked benefit to this reduced heat is that the customer will be more comfortable. Due to the Energy Policy ACT, retailers will have very little choice but to use energy-efficient incandescent lamps for their display lighting. Even if lamp manufacturers are trying to develop standard incandescent replacements to the outlawed R-lamps, we designers and specifiers we do not have to use these new replacements. We can show our clients that using halogen PAR-lamps can produce better contrast, save energy, and produce a whiter crisper light. A good place to find information on the design issues for retail in with the IESNA RP-2-85 Lighting Merchandising Areas . This publication is filled with good ideas and recommendations on retail lighting. The first table gives us a good starting point on ways to reduce the energy use: High Activity Area -- Where evaluation and viewing time is rapid.
Medium Activity Area -- The customer may require time and/or help in evaluation of the quality of the merchandise.
Low Activity Area -- The customer may be unfamiliar with the inherent quality and will need assistance.
So in which of these three lighting areas, circulation, merchandise, and featured displays, would it be the easiest to save the energy in? The answer is none of the above. What we need to look at is the contrast ratio of the three IESNA activity areas. Notice that the merchandise should have about 3 times the light level as the circulation, and the featured displays should have about 15 times the light level as the circulation. The contrast ratios among these three ISENA activity areas are the same even though they provide different light levels. So picking the correct activity area for the type of retail will make the biggest difference in energy efficiency. Let's group the circulation and merchandise areas together under the same lighting system, and light them with either a fluorescent or HID system (if HID is appropriate from a color stand point). If we light this to the merchandise light level what happen s to the circulation light level? The circulation light level will be higher than necessary, but sense we are measuring the light levels at different heights the light levels and the recommended contrast ratios may not be that far off. If everyone reading this article from today on will not use track lighting to light the general merchandise, we can take the heat out of retail. Does every dress, every shirt, every pair of pants need its own spot light? Of course not. Lighting all the merchandise to the same light level minimizes the impact that the featured displays can achieve. The track system's versatility is most useful in lighting featured displays, which may change from week to week. Here again, the punch from the halogen incandescent (White HPS or Ceramic Metal Halide will be even more energy efficient) will achieve the desired contrast ratios. So my two simple rules for taking the heat out of retail are:
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