Lumens, not Watts

One hundred years ago, our soldiers were shipped “over there” during World War I. Back home in Arkansas, “country folks” who lived outside the larger cities managed life and work without electricity. Many would wait another 20 years, until after the end of World War II, to enjoy the marvel of electric power. At sunset, wax candles and oil lanterns extended the day by emitting low levels of light. Each candle or lantern wick would emit 13 to 37 lumens per fixture. That’s not much light by today’s standards.

Speaking of standards, when it comes to lighting our homes, many of us are accustomed to thinking about wattage, which is the unit measurement for power. We’ve had this mindset since Thomas Edison created the first practical incandescent lightbulb. Until recently, most homes included 60-, 75- and 100-watt bulbs. When we wanted more light in an area, we installed a higher-wattage bulb. But, higher-wattage bulbs use more power, emit more heat and chalk up more kilowatt-hours.

Lighting as we know it is transforming. Incandescent bulbs and compact fluorescent lamps (CFLs) are phasing out, while energy-efficient light emitting diode (LED) bulbs are becoming the new norm. LED retail prices have dropped significantly, and supplies are abundant. Most large retail and big box stores have huge displays of various LEDs, including general purpose, recessed, floods and even candelabras for ceiling fans.

What makes the LED a bright idea is that is has a high-lumen output while consuming 85 percent less power. For instance, a general purpose incandescent bulb consumes approximately 100 watts of power while emitting 1,600 lumens of light. An energy-efficient LED counterpart consumes 15 watts of power while emitting the same 1,600 lumens of light. Simply put, a lumen is the measure for light’s brightness. The higher the lumen output, the brighter the bulb.

You may have noticed [different] labeling on lightbulb packaging [than years past]. This is because the Federal Trade Commission (FTC), under direction from Congress, has issued standards to move America away from focusing on wattage when shopping for lightbulbs. For instance, the front of a lightbulb package must include the brightness, or lumens, and the estimated energy cost per year of the bulb. The back of the package must include the brightness, annual energy cost, life expectancy, light appearance, and, lastly, the wattage.

Light appearance, also called “color temperature,” is measured by the Kelvin (K) scale. If you enjoy a cozy, warmer light, shop for LEDs that range between 2,700 and 3,100 K. The whiter, vibrant light colors range between 3,200 and 4,500 K. Daylight and invigorating colors range between 4,600 and 6,500 K.

The wattage was once the determining factor for bulb selection. Today, we look to the brightness, or lumens, of the bulb. Think of it this way: we fuel up our cars with gallons of gasoline, enjoy electricity by the kilowatt, purchase apples by the pound, and replace bulbs by the lumens.

Originally published in Arkansas Living in May 2017 by Bret Curry.