Solid-State Lighting for Refrigerated Display Cases

The intent of this paper is to initiate a discussion within the community interested in commercial refrigerators, on the possible use of LED lighting in commercial refrigerated and freezer display cases. The fluorescent lighting presently used in commercial refrigerators is inefficient in the application and also it provides poor lighting for merchandising. LED is a solid-state light source that is rapidly evolving as an energy efficient long life light source. A laboratory human factors experiment was conducted to assess the preference for the different lighting systems. Two refrigerated display cases, one with the traditional 4-ft T8 fluorescent lighting system and the other with a prototype LED lighting system, were placed side-by-side in a laboratory setting. Compared to the lighting produced by a single large source such as a linear florescent lamp, the lighting produced by a distributed LED lighting system was more uniform. Sixteen human subjects participated in this study and rated their preference for the two lighting systems. The results show that human subjects strongly preferred the display case with the LED lighting even though the LED system produced less than half the flux of a fluorescent system. At the present time a properly constructed LED lighting system for refrigerators would have similar energy consumption as a fluorescent system. Since the LEDs are still in their development phase, at the present time they are much more expensive than fluorescent systems. With the proposed advancements in the efficacy of LED systems, one can expect future commercial refrigerators to be equipped with LEDs that can provide better lighting. In addition these new LED based lighting systems would consume less than half the energy as compared to the fluorescent lighting systems.