Wattage, lumens and lux ... what the heck do these terms mean? These terms are commonly found on lighting labels and packages. But the average homeowner has little to no understanding of what they actually mean. If you're one of these homeowners, here is an explanation that might help. And for even more terms, read this article featured on AngiesList.com.
Wattage
Wattage is simply the measurement of electrical power, in watts. Watts are calculated by multiplying the amperage, which is the strength of an electric current, by the voltage. On your energy bills you may have noticed the phrase “total wattage consumption." This is what you are billed by. Incandescent bulbs run about 60 watts, LED bulbs 12 and CFLS 15. Remember, the lower the wattage, the lower your electric bill will be. The wattage of a bulb is not the measurement of the bulb's intensity. It’s simply the amount of power necessary to produce its light or intensity.
Lumens
The actual definition of a lumen is ... a doozy. We'll leave that to Merriam-Webster. In common-speak, a lumen is a simple measurement of the intensity or brightness of light. This term has only recently been added to light bulb packaging. Lumens only measure brightness, not energy use. When shopping for bulbs, consumers should look for lumens so they can buy based on the brightness they want. The knowledgeable professionals from Earth LED compare lumens to light like gallons to milk or pounds to bananas. It’s a clever way to think about how much light you want to buy.
Lux
What is sometimes called illumination or illuminance, lux can be defined as the standard unit of measurement of light level intensity. Lux and lumens must work together. One lux is equal to one lumen spread over the space of one meter. The measurement of lux tells consumers how many lumens (or the total light output) are needed based on a measured area that consumers are trying to illuminate. A brightly lit office space requires about 400 lux. Compare that to outdoor sunlight which tops out at around 100,000 lux, according to the lighting experts from Green Business Light, a UK-based company that supplies and installs energy-efficient lighting.
Manufacturers are working to make lighting terms more understandable for the everyday consumer. A helpful lighting facts label on light bulbs is required by the United States Federal Trade Commission. It resembles a food label and provides valuable information to help consumers and homeowners make informed decisions. This lighting facts label appears on light bulb packaging and includes estimated yearly cost, brightness, light appearance (warm or cool), life expectancy (based on three hours of use each day), mercury information and energy use.