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Fluorescent lights have grown in popularity due to their energy efficiency and lower utility bills, but there are conflicting beliefs about whether they should be left off or on when you leave a room. Turning a light on and off frequently would certainly reduce its life and use more energy, but so does leaving the light on all day. So, what is the more cost-effective solution? Read on to get the real scoop.
When Should You Leave Fluorescent Lights Off?
Whether you flip the switch mostly depends on how often you “come and go” in any given room. According to the Department of Energy, you should turn fluorescent lights out if you will be out of a room for longer than 15 minutes. However, there is a bit more nuance to the rule. It’s a myth that turning on and off fluorescent lights uses more energy than just leaving them on. Yes, it takes more energy to start up (turn on) a fluorescent light, but that additional energy only lasts a fraction of a second. When on, a fluorescent light is much more efficient than incandescent bulbs.
When Should You Leave Fluorescent Lights On?
Go ahead and light the light shine if you plan to return to the room in a few minutes. In fact, fluorescent bulbs don’t lose any “life” when left on for up to three hours. To understand why this is the case, you need to understand "burn time."
Fluorescent lights have a coating of electrodes that allow them to work. The light burns off a small amount of those electrodes every time you turn it on. Fluorescent lights are generally rated to last about 20,000 hours when run for three hours at a time. This means you would get about 6,667 starts out of the lamp over its life under this calculation.
What does this mean for you? Don’t constantly switch fluorescent lights on and off unless you want to burn through the bulb more quickly.
Energy Efficiency of Fluorescent Lights
Fluorescent lights are among the best types of light bulbs you can buy. They are much more efficient and won't waste as much energy if left on for long periods. Simply put, it takes less energy for fluorescent lights to convert ultraviolet emissions into light using the coating on the inside of the tube than it does for a traditional bulb to burn a filament.
Also Consider Your Utility Charges
Photo: fizkes / Adobe Stock
According to the Department of Energy, here are the main factors you should consider when determining whether to turn your fluorescent lights out immediately after leaving a room:
Whether a utility charges based on customer "classes" (residential, commercial, and industrial)
Whether a utility charges different rates based on time of day
Whether a utility charges different rates for peak and off-peak hours
Whether a utility charges higher rates once you hit a certain baseline of usage
Whether a utility adds extra charges for each kilowatt-hour consumed
It’s probably best to play it safe and just shut off your lights. It certainly can’t hurt, and it may save you some money on your next energy bill.
Using Motion Sensors to Switch Fluorescent Lights On/Off
Motion sensors are a great way to make sure your fluorescent lights shut off if no one is in the room. You can buy a simple motion sensor that connects to any light fixture, fluorescent included, for between $20 and $80. These are simple home devices that won't require you to hire an electrician to install it. Once it is installed, you won't have to worry about leaving a bulb on for longer than it should be.
