We haven’t yet reached the lowest claimed lifespan of 6000 hours, but our results so far give a good indication of how the bulbs are performing. Scores
The overall score is comprised of decrease in luminosity (60%) and initial luminosity (40%). Decrease in luminosity
score is based on the light output after 2000 hours operation. The closer to the initial luminosity, the better. The lowest-scoring models dimmed to the equivalent of a 60W bulb, or less. Initial luminosity score
is based on the light output of the bulb after 100 hours burn-in. The closer to the luminosity of its claimed equivalent incandescent (typically 75W), the better. The best-scoring models started brighter than their claimed equivalent. Warm-up time
is the time taken to reach 80% of maximum brightness. Claimed wattage
is the labelled actual wattage for each bulb. Our measurements indicate this is a reliable figure. Claimed life expectancy
is the number of hours the bulb should last in normal operation (about five hours on per day). The bulb’s lifetime can be reduced by unusual operation, such as very frequent switching on and off or being situated in extremely cold or hot locations. Price per bulb
is based on what we paid in November 2009. Some come in packs of two.