Cost efficiency defined by the ratio of product to dollar provides a logical basis for assessing overall LED value. The custom LED lighting industry refers to this ratio as lumens per dollar, where lumens represent the overall photometric, or luminous flux from the LED lamp. Light emitting diodes with a higher lumen per dollar value offer increased lumionous output at a decreased per-component cost. To calculate lumens per dollar, simply multiply the typical lumionous output rating by the reciprocal of per component cost. Corresponding LED lamp datasheets typically state a luminous output rating in lumens (lm). In some cases, datasheets offer only the milli-candela or mcd rating. To convert candela rating to luminous output, the LED beam angle is also required. Some LED indicators offer greater cost efficiency in low volume or single quantity purchases. Others may offer increased efficiency in higher volumes such as production quantities. It only makes sense to calculate lumens per dollar based on volume-pricing information since mass production is the time that lumens per dollar will count most.
For demonstrational purposes, assume a particular project requires 120 lumens to meet specific application requirements. An LED light rated for 60 lumens sales for $4.00, so only two LED lights are required to meet the 120-lumen requirement. Another light emitting diode rated for 40 lumens sales for $2.50, so three LED lights are required to meet the 120-lumen requirement. Although the LED rated for 60 lumens offers an overall increased lumionous output, it only offers 15 lumens per dollar. The LED rated for 40 lumens offers 16 lumens per dollar. In this example, the LED rated for 40 lumens offers increased cost efficiency. It is important to perform this calculation for all LED lighting designs.
Lunar Accents Design Corporation employs an extensive component database containing thousands of possible LED lamp candidates, for new product designs. This database offers various search parameters including lumens per dollar data based on our discounted volume pricing. This powerful information is invaluable while considering LED candidates for specific application requirements. Normally it could take several months to contact individual LED manufactures and achieve price quotations required to calculate for corresponding lumen per dollar data. As opposed to spending hours online or sifting through component datasheets, our applications engineers are trained to perform customized searches based on a variety of input criteria.
LED manufactures race to conquer the challenge of replacing conventional light sources with solid-state LED lighting. As 2006, LED indicators lack significantly in terms of cost efficiency when compared to conventional light sources. As technology progresses, LED lights become more cost and energy efficient. New technologies in conjunction with lower manufacturing costs will continuingly increase the lumens per dollar ratio. Eventually, a point will come when replacing conventional lighting with LED lighting makes more finical sense.
In a world of high power LED lights, it is important not to forget about the smaller and less efficient LED light predecessors. A variety of smaller, less efficient LEDs are extremely useful in many applications including some LED tail lights. It may seem bizarre that LEDs offering fewer lumens per dollar can be so beneficial. This is only because of specific advantageous features that ultimately outweigh the benefits of cost efficiency. For example, an LED array enclosed within a narrow sealed casing may not operate properly when equipped with high power LED lights. Although the high power LED lamp provides more lumens per dollar, thermal management is the major concern. In addition, the larger more powerful LED indicators may not fit in the restrictive space. A series of smaller less powerful LEDs are required because the alternative characteristics are more important than cost efficiency. Yet another example includes an application requiring light in a very specific location. High power LEDs tend to dissipate an excessive amount of light within a very restrictive area. This high intensity feature is not always favorable in specific applications. An example is an automotive taillight application, which requires an even distribution of light behind the taillight lens. For this application, a series of smaller less powerful LEDs can provide sufficient light in the critical areas. Once again, cost efficiency suffers, but the alternative benefits outweigh cost efficiency.