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by Chris Johnson
If someone from the '90s time traveled here to present day and had a look at our light bulbs, he'd know something was up. Lighting technology has evolved so much in the past few decades, it only makes sense that we need a different language to describe it.
Using a lamp's wattage to ascertain its brightness (the higher the wattage, the brighter the light), doesn't work anymore. Consumers used to be able to picture a light's brightness relative to the amount of watts it used, because there were so few light sources to choose from. The numbers were pretty standard.
However, wattage technically measures how much energy your light bulb uses, nothing about brightness. Newer sources like CFLs and LEDs produce much more light from less energy - so, we need a more accurate way to measure light output.
Enter the lumen.
A lumen is an international unit of measurement that describes the amount of light (or brightness) produced by a light source.
This scale is universal, and you can use it to measure the brightness of any light source from incandescent to LED, metal halide to fluorescent, and everything in between. The lumen scale is a concept in physics that has been around for a while, but its only now becoming popular, as the light source pool diversifies.
It's easy to find out how many lumens a light bulb emits. As of 2011, the FTC requires a lamp's lumen output to be highlighted on its consumer packaging. Just look for it on the package's Lighting Facts Label.
As we all adjust to this scale, it might be helpful to get to know these new measurements in terms of the old ones:
Of course, lumen measurements are always approximations. They can vary slightly, depending on the lamp's manufacturer, the age of the lamp, if there's dirt or dust on it, if it's clear or frosted, the lamp's voltage rating, and the exact voltage of the circuit.
Despite these marginal factors, the lumen is still the most accurate measure of your lamp's brightness.
To find the most energy-efficient light bulb to fit your exact needs, determine all the light bulbs that produce your desired number of lumens, and select the one with the lowest wattage.
Written by Chris Johnson
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