January 1, 2007—A Department of Energy (DOE) pilot test of four light-emitting diodes (LEDs) has shown that although many energy professionals expect solid-state lighting sources such as LEDs to be the ultimate winner in energy-efficient lighting, they currently fall short of their claimed output.
The pilot tests examined two “downlights”—the type of spotlight that is typically recessed into a ceiling—as well as a task light and an under-cabinet light. The test results, which protect the identity of the LED manufacturers, found that all four lamps fell far short of their claimed output in terms of lumens of light per watt of energy.
The manufacturers claimed lighting efficacies of 36 to 55 lumens per watt, while the pilot test found efficacies of 11.6 to 19.3 lumens per watt, placing them below compact fluorescent lamps (CFLs) in lighting efficacy.
The study suggests that manufacturers are relying on measurements of how much light an isolated LED produces versus how much the light an LED lamp actually delivers. DOE is continuing its tests to better understand the observed discrepancies.
For the test results and more information, visit DOE’s Solid-State Lighting Web site.
