The Benefits of Turning Your Lights Off — This Green Lifestyle

There are four main types of light bulbs in use across the world: incandescent, fluorescent/CFL, Halogen, and LED. Of these, incandescent light bulbs are the least energy-efficient, while LEDs are the most energy efficient. Let’s take a brief look at each of these:

Incandescent

An incandescent light bulb uses a metal filament that is heated until it glows. The energy used to do this is primarily given off as heat, with only about 10% going towards the lighting. Although this type of light bulb is being phased out in some places, many homes and cities still use incandescent light bulbs as their primary form of light.

In addition, incandescent bulbs usually use anywhere from 25 to 100 watts (W) of electricity. 25W translates to 0.025kWh, which you can then use to calculate the amount of electricity a light bulb uses when it’s used for, say, 500 hours in a given year (12.5W).

Fluorescent or CFL

Standard fluorescent lights come in tubes and are commonly used in industrial buildings and classrooms. CFLs are compact fluorescent lights that, as the name suggests, are a more compact type of fluorescent light bulb for use mainly in the home.

Fluorescent light bulbs convert UV emissions with a fluorescent coating inside the tube. As explained by StouchLighting, “the UV radiation is generated in the first place by an electrical charge that is run through the inert mercury glass internal to the bulb.” Even more so than other lights, fluorescent lights require a pulse of electricity in order to ignite, which can be more significant with larger lights.

In general, however, fluorescent lights (especially CFLs) are more energy-efficient than incandescent lights. Because of the initial voltage required to ignite the bulb, and the effect of switching on and off on the lifespan of the bulb, it’s best to turn these bulbs off when you’re going to be out of a room for at least 15 minutes.

Halogen

As with incandescent light bulbs, halogen lights are only about 10-20% efficient, meaning that 80-90% of the energy used is released as heat! However, they are slightly more efficient than incandescent bulbs due to the gas inside the bulb; halogen prevents the build up of soot from the burning metal filament, which increases the lifespan of the bulb.

Why does lifespan matter? Well, as with anything, light bulbs require a lot of energy in order to be produced and transported in the first place. Even if the energy usage is similar, a light bulb that lasts twice as long is going to have less of an environmental impact.

LED

The modern hero of the light bulb is the light-emitting diode, or LED. LEDs on average use only 2 to 18W and have a much longer lifespan that is unaffected by switching on and off. Although all light bulbs should be switched off when not in use, LEDs in particular can handle frequent switching, making them the perfect candidate for motion-sensored lights, for example.

Although an LED light bulb might have a slightly higher initial cost, it can save hundreds of dollars in energy cost over the course of its life. Not to mention, LEDs are 100% recyclable!

Does turning light bulbs on and off use more electricity?

You may have heard before that turning lights on and off frequently uses more energy than if you were to just leave them on.

While it’s true that incandescent light bulbs require an initial surge of electricity to turn on, this levels out quickly. In fact, Mythbusters tested this in a series of experiments, and concluded that in terms of energy savings it’s best to turn lights off when leaving a room for more than a few seconds.

Even for fluorescent light bulbs, which use the most energy to turn on, it’s more energy efficient to turn the lights off when not needed for at least 23 seconds. That said, due to the impact of switching on and off on the lifespan of a fluorescent light bulb, it’s best to limit frequent switching.

In contrast to CFLs, LEDs are not impacted by switching on and off since they don’t need an initial surge of energy in order to ignite. This makes them the perfect choice for situations where you might be frequently turning lights on and off.

Where is the energy coming from?

All light bulbs require electricity to function. But where is that electricity coming from? The answer varies depending on where you live.

In all cases, energy first has to be generated. Sources of energy include non-renewable resources such as coal and natural gas, but there are also renewable sources of energy such as wind, water, and solar. If your home has solar panels, you might even be supplying your own energy, or at least some of it.

However, energy isn’t free. It’s not free to you (that is, it costs you on a typically monthly basis), and it’s not free to the environment. You can learn more about the importance of renewable sources of energy here.