LED Lightbulbs: The How and Why

An LED lightbulb.

When people think of LEDs, they often think of those tiny blinking lights on computer monitors and the ones inside alarm clocks. LEDs are indeed used for these types of applications, but they are increasingly being utilized for other uses as well. Amidst concerns about the energy consumption of traditional incandescent bulbs, LEDs are championed as a potential replacement for everyday household use. You can get LED bulbs for table lamps, ceiling fixtures, flood lights, and car headlights.

How the LED Works

“LED” stands for “light emitting diode.” It is a semiconductor device that illuminates when an electrical current passes through it. LED bulbs are incredibly efficient. They use less energy to give off as much light as traditional bulbs, and they last much longer (most are rated to last 23 years with three hours of use per day). When they do go out, it is not in one fell swoop, like an incandescent bulb. An LED will gradually give off less light, and the light may change color when it is nearing the end of its life.

LEDs come in colors, including red and green. Many traffic lights, in fact, are made with LED lighting. However, there are no white LEDs. To attain the white light used in homes and offices, manufacturers mix LED colors at different wavelengths, or apply a phosphor material as a filter.

An LED will only cast light in a single direction. On its own, it can’t fill a room with light like a traditional bulb can. For this reason manufacturers engineer reflectors and lenses in LED bulbs and fixtures to distribute light more evenly. The government’s ENERGY STAR program tests LED bulbs for light distribution (among other qualifiers) and awards its seal to brands that closely replicate the lighting experience of a traditional incandescent.

Comparing LEDs to Other Bulbs

One of the main selling points of the LED is its energy efficiency compared to other bulb types. Bulbs are measured in terms of watts and lumens. Watts refer to the amount of energy a bulb consumes, and lumens refer to the amount of light it gives out. An incandescent bulb uses 60 watts to produce 800 lumens. An LED bulb uses only 9 or 10 watts to produce the same amount of lumens.

Compact fluorescent light bulbs (CFLs), characterized by their swirly glass tubes, are another energy-efficient, traditional bulb alternative. They use 14 or 15 watts to produce 800 lumens. However, many people have found them to be an unsatisfactory replacement for incandescents because they give off an unflattering light, sometimes flicker, and can take up to three minutes to become fully lit. In addition, their lifetime shortens when they are turned on and off frequently, or lit for only short periods.

LED bulbs, however, fully illuminate immediately. They do not contain mercury like CFLs do. The quality of light differs across brands. Some household LED bulbs give off a harsh, almost blue or green light, while others are more successful in replicating the warm light of an incandescent. The best way to test LED options without spending a lot of money is to visit a lighting store that has different brands on display.

LEDs are more expensive than other types of bulbs (about $10 is the industry standard for a single, general household bulb). However, they are up to 80 percent more efficient than traditional bulbs, so the upfront cost is offset by utility savings. Replacement costs are reduced as well due to their longevity.