Incandescent is the standard light bulb that we all know. Early versions of this technology showed up in 1760 and the early 1800s. Joseph Swan and Thomas Edison commercialized the early incandescent bulb and it evolved into the standard bulb that we have used the majority of our lives. With incandescent bulbs electricity flows through a filament made from tungsten. The filament is in a high temperature glass container with inert gas creating a vacuum. The lifespan of an incandescent bulb is about 1,000 hours on average. They put off a lot of heat (roughly 56 BTUs per hour) and are damaged easily. They are not energy efficient, typically producing 16 lumens per watt on average.
The CFL or compact fluorescent began replacing the incandescent bulb. Many of us refer to these bulbs as the “spiral” bulb. Electronic ballasts in the base of the light excite mercury atoms in the glass tubes causing the radiant ultraviolet light. CFLs contain mercury which is toxic, making disposal complicated. The lifespan of a CFL bulb is about 6,000 hours on average. CFLs do put off heat, but less than incandescent (roughly 20 BTUs per hour). They are more energy efficient than the incandescent bulb and are about 60 lumens per watt on average.
LED or Light-Emitting Diode, is the new industry standard for lighting. Although LED technology came out in the late 1920s, it has been used more recently for lighting because of its advantages over incandescent and CFL. LEDs are semiconductor devices. When suitable current is applied to the LED, electrons are able to recombine with electron holes. Energy is then released in the form of photons as a byproduct. The lifespan of LEDs is 50,000 hours on average. They put off very little heat (roughly 2 BTUs per hour), and do not contain mercury unlike CFLs. LED is currently the most energy efficient lighting in the market, putting out 150 lumens per watt on average.