The earliest light bulb, known as the electric arc lamp, was invented by English chemist and inventor Humphry Davy in 1802. However, it wasn't practical. While Thomas Edison is widely credited with inventing the first commercially viable incandescent light in 1879, he wasn't the first. Some historical records suggest there were more than 20 inventors of incandescent lamps before Edison. Edison's invention combined three factors that surpassed competitors' bulbs – a useful incandescent material, a higher vacuum, and high resistance that made power distribution from a centralized source economically viable. The Edison Electric Illuminating Company of New York was founded in 1880, then merged with two competing companies in 1892 to form General Electric.
Modern incandescent bulbs aren't energy efficient because only 5–10% of electrical power supplied to the bulb is converted into visible light, while the remaining energy is wasted as heat. Governments worldwide have passed regulations to phase out incandescent light bulbs in favor of more energy-efficient alternatives. Modern compact fluorescent light (CFL) bulbs use about 75% less energy than incandescent bulbs and last about ten times longer.
Edward Hammer of General Electric first invented Spiral-shaped CFLs in 1976, but his initial design was shelved because the new machinery needed to mass-produce these lights was too expensive. When they hit the market in the mid-1980s, CFLs were big, bulky, and costly ($25-$35). Although their design improved and they became affordable, CFLs have mainly been replaced by light-emitting diode (LED) bulbs.
The first rudimentary LED bulb was invented in 1962 by Nick Holonyak Jr., who was working at General Electric. Initially, LEDs only emitted red light, limiting their use to indicator lights and lab equipment. Today, they're available in ultraviolet and infrared spectrums, making them useful for a wide variety of lighting needs. LEDs can be single diodes (e.g., a flashlight) or groups of diodes used to create light bulbs.
LED bulbs tend to be starker than incandescent bulbs because they're most efficient when emitting a blue-white color. A spectrum bar on the package 'Lighting Facts' label indicates a yellowish or bluish light – an essential consideration for those who prefer warmer tones. By 2012, more than 49 million LED bulbs were being used across the U.S., saving an estimated $675 million in energy costs. According to industry data, LEDs outsold all other types of bulbs for the first time in 2017.
LED bulbs produce visible light through electroluminescence, a process that involves energy passing through a semiconductor microchip. The heat produced by LEDs is absorbed into a heat sink to prevent performance issues, unlike incandescent and CFL bulbs that emit light and heat in all directions. LEDs are "directional" light sources, emitting light in a specific direction. This enables LEDs to use light and energy more efficiently for a diverse array of applications. For example, newer LED bulbs with diffuser lenses and reflectors create wider spread light, making them ideal for table lamps.
When designed well, LED lights are more efficient, versatile, and last longer than incandescent and fluorescent options. The useful life of LED bulbs is defined differently than that of incandescent bulbs or CFLs. LED bulbs typically don't "burn out" or fail – instead, they experience lumen depreciation. This results in their brightness dimming slowly over time. An LED's lifetime is based on a prediction of when the light output decreases by 30% or produces 70% of the initial lumens (L70). A single LED bulb lasts 2 to 5 times longer than a CFL and up to 50 times longer than a standard incandescent bulb. On average, an LED has a lifespan of 25,000–35,000 hours. If you only have lights turned on three hours a day, this would equate to 20 to 30 years! Estimates suggest that a single LED is discarded for every five CFL bulbs or 30 incandescent bulbs. Since they don't contain delicate filaments of glass, LEDs can withstand light impact without breaking.
Brightness is determined by lumens – the measurement of light. LED bulbs require much less wattage than CFL or Incandescent light bulbs, which is why they're far more energy-efficient. It can be confusing when you first buy LED bulbs because their wattage is far lower. The following is a handy comparative reference to use when shopping.
LEDs in various price ranges are available at any hardware or home improvement store and any number of online retailers. When shopping for light bulbs, it's essential to consider whether they'll be used indoors or outdoors, the illumination level, wattage of the bulb to match your fixture, and the desired color temperature.
Saving energy with LEDs is as simple as replacing the light bulbs – doing so will reduce your carbon footprint and save money – a win-win for you and the environment!