Experts say the answer depends on the type of lighting, how long lights are left on, and whether smart systems are in place.

So, do you really need to turn off the lights every time you leave a room or aren't using it? The answer is sometimes yes, but oftentimes no—and it mostly depends on the type of lightbulbs you use.

Being called from across the house to be asked why all the lights are on in an empty room is a childhood experience many of us had, instilling in us the need to switch off all lighting whenever we ...