Issue #13: Turning Off Lights?

Dear Sustainable Abigail,

One refrain that has persisted from my very first introduction to living a more sustainable life to now is to always, always turn off lights whenever leaving a room. Of course this makes sense, wasting energy is bad and this is a quick simple way to avoid doing so, but my question is whether this refrain is as universally applicable to all situations as it seems? That is, should I ALWAYS turn off lights, even if I’m only going to be gone for 30 secs? No? At what point is it saving electricity? Thanks!

-On Again Off Again

Dear On Again Off Again,

This is a great question, and something I’ve often wondered about myself. After I started to do a little digging, I found out that the answer is pretty dependent upon the type of light bulb. So, let me break it down for you, beginning first with the most common (and unfortunately least energy efficient) residential lighting: Incandescent Lights. Incandescent lights are those that one might think of as “typical” light bulbs, or recognize from an early 2000’s “The Fray” album cover. These lights are quite inefficient due to only about 10% of the energy that they use producing light, with the rest actually going to giving off heat. What all of this means is that if the lighting in a room uses incandescent bulbs, you should flip the off switch really whenever you can. The same actually goes for another type of lighting, “Halogen lighting,” which are also relatively inefficient (though more efficient than Incandescent lights), so worth turning off whenever possible. Now, it gets a little trickier when it comes to other types of lighting, like Compact Fluorescent Lamps (CFLs). While there are a variety of types of CFLs, one type that you might recognize is the “spiral” CFL bulb, the type that has multiple strands making up the bulb shape. CFLs use about 75% less energy than incandescent bulbs, and because turning them off and on shortens their life span, there is a different standard for what to do with these lights. Here’s what I’ve found for situations where a CFL bulb is used: “if you will be out of a room for 15 minutes or less, leave it on. If you will be out of a room for more than 15 minutes, turn it off.” Last but not least are LED lights, which are great because not only are they more energy efficient, but also their lifespan is unaffected by turning them on and off! These bulbs are particularly relevant to us here at Bates, because Bates is in the process of converting to LED bulbs campus-wide! Hooray! I hope that this was helpful to you, and if you want to learn more about this topic in general here is the great source that I used for my own research: As you can see, there are a couple factors that play into this question of when to turn off lights, but overall, as long as the bulb is not a CFL, it is safe to say you should always try to turn off the light! Thanks for writing!

-Sustainable Abigail


*Content originally published in The Bates Student Newspaper*