Ever thought about what you should consider when buying a light bulb?  Any clue what a lumen is?

Chances are if you’re heading out to your local supermarket or hardware store to pick up some light bulbs, you’ll find a store attendant and ask what aisle the 100W (or 75W, 60W, etc.) light bulbs are in and pick up a package.

Now, say you head to the car dealership looking to purchase a new ride.  You’ll walk around the lot as a salesperson shows you vehicle after vehicle.  And each time you approach a new car, the first question you ask the salesperson is:  “what’s the gas mileage?” or “how many miles per gallon does this car get?”

When we purchase light bulbs, we traditionally think in terms of and classify them according to their wattage, or how much energy they use.  When we purchase vehicles, we classify them according to their MPGs, or how efficiently they use energy.  Interesting, isn’t it?  Purchasing technology according to efficiency (performance as a ratio of output to input) seems to make more sense than just energy use (input).   Would you ask a car salesman for a car that “uses 20 gallons of gas per hour?”  No.  So why ask a store attendant for a bulb that uses 100 watts?  You no longer have to.

The way we communicate about light bulbs and energy use is changing.  Until recently, light bulb technology hasn’t changed much since Thomas Edison first commercialized electric light well over 100 years ago.  Over this long period we have always referenced the amount of energy needed to power a light bulb.  Today, consumers have a choice between halogen, compact fluorescent (CFL), and solid state (LED or light emitting diode) technologies.  The lighting market has transitioned to technologies that use less energy and last longer than the general service incandescent that has been the standard since Edison’s day.  This change means we can no longer use energy use as a metric to compare the bulbs we buy (for more information, download NEMA’s “Lighting Options for Your Home” brochure).

To keep up with the transitioning market, the lighting industry has developed a new labeling system that will enable consumers to compare bulb technologies based on energy efficiency, as opposed to energy use, and brightness.  Instead of shopping for light bulbs based on wattages, consumers will now search for bulbs according to the number of lumens they output and how efficiently they produce these lumens.  (What’s a lumen you say?  A lumen is a measurement of a bulb’s brightness or light output.  The brighter the bulb, the higher the lumens.)  For applications where a large amount of illumination is required, such as an outdoor flood light, consumers will seek out bulbs with a high lumen count; for low light situations, such as a desk lamp, a lower lumen count bulb would be used.  And regardless of application, the higher the efficacy (lumens per watt ratio), the better.

The advantage of classifying light bulbs by lumens (output) and wattage (input) is that this gives consumers the ability to evaluate bulbs based on their efficacy (performance as a ratio of lumens per watt).  So the next time you’re wandering down the aisles of your local hardware store looking for a light bulb, treat the store rep like a car salesman and ask: “how many lumens per watt does this bulb get?”


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