Is It Cheaper To Leave Your Lights On? Here's What You Need To Know

There's a decades-old myth that says it's cheaper to leave your house lights on all the time than to turn them on and off when you enter and exit a room. The belief is so widespread that even the "Mythbusters" decided to test it on the 2006 episode titled "22,000 Foot Fall." The Build Team busted the myth, but are their findings still relevant after 20 years of changes in light bulb technology?

Recent findings from the U.S. Department of Energy are mostly in line with what the "Mythbusters" discovered back in 2006. It is almost always preferable to turn the lights off when leaving a room, but with one notable exception: If you are using compact fluorescent lamps (CFLs), it is actually more efficient to leave the lights on if you expect to come back within 15 minutes. For the sake of energy consumption, as well as bulb longevity, it's generally totally fine to switch the lights off when not in use.

The basis of this age-old myth is that energy consumption spikes when you turn on the lights. The filament requires a surge of energy in order to adequately warm up. This is completely true, but that spike is extremely short and overall negligible compared to energy consumption over time. It's in the best interest of your energy bill and your bulb's longevity to flip the switch when you leave the room in almost every imaginable scenario.

CFLs present the most noteworthy exception for the average homeowner. It's also worth mentioning that industrial-grade light fixtures, such as HIDs, do not follow the typical rule of thumb either. This is because industrial light fixtures have longer warm-up times, ranging from three minutes all the way up to 20 minutes, depending on the lamp type, making the turn-on more costly and more impactful on the lamp's longevity. However, LED lights represent the most widespread bulb type today, with OLED lighting making a name for itself in recent years as well. Even many of the best smart light bulbs are LEDs, so it's worthwhile to automate your smart home to turn off a room's lights when no one is there.

If you've ever tried leaving the lights on to help reduce your energy bill, there are other simple tricks you can try that may be more effective for you. Many smart home upgrades work wonders when it comes to saving money for homeowners over time. Findings from E Source, reported by the EPA, show that smart lightbulbs have the potential to save 30% more energy compared to non-connected lighting. Smart thermostats, smart plugs, and smart appliances can save you 19%, 21%, and 6% on your energy bill, respectively.

Of course, an even cheaper way to cut costs is to simply unplug power-hungry appliances that are actively contributing to your energy consumption. Routers, video game consoles, and even coffee makers with always-on displays are constantly consuming some degree of "standby power." You have nothing to lose by unplugging these devices overnight, especially since they might be adding to your energy bill more than a few light bulbs.