Product Selection Guide Page 1112 Product Selection Guide-11th Edition

1112 PRODUCT INFORMATION Photometric Measurements LED TECHNICAL INFORMATION PSG11 TECHNICAL INFORMATION The consequence is that, unlike traditional photometry, efficiency in the world of LED lighting is a quantity that gives no meaningful information about the performance of the LED luminaire. For first-level comparisons, it is the luminaire lumens that must be compared for LED luminaires - rather than fixture efficiency. In addition, the metric of luminaire (delivered) lumens is common to both absolute and relative photometry and therefore allows for a direct comparison of products measured with both methods. As with traditional files, the generated photometric report for LED luminaires gives the measured lumens, distribution and wattage of the tested luminaire. In some cases, additional information on the CCT and CRI of the luminaire is also provided, but not required. If needed, the generated electronic file is converted to standard "IES file" format for absolute photometry specified in IES LM-63-02 (Standard File Format for the Electronic Transfer of Photometric Data and Related Information). This file format is easily used in programs such as Visual to calculate the initial performance of the luminaire within a 25C ambient environment. In ambients other than 25C, an appropriate Luminaire Ambient Temperature (LAT) factor must be applied to account for the temperature response of the LED luminaire. This set of factors (LAT vs. temperature) is specific to each luminaire and is provided by the luminaire manufacturer. It is based on rigorous testing of the luminaire as well as information the luminaire manufacturer receives from their selected LED supplier. There is a host of additional excellent literature that can be found on this topic under the measurement series of documents listed at the Department of Energy's site: (Continued) PHOTOMETRIC MEASUREMENTS

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