# Cheaper to leave the lights on? **URL:** \ **Category:** Factual Questions\ **Created:** [July 12, 2016, 3:28pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724 "2016-07-12T15:28:19Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Horatio\_Hellpop](https://avatars.discourse-cdn.com/v4/letter/h/e5b9ba/32.png) [@Horatio\_Hellpop](https://boards.straightdope.com/u/Horatio_Hellpop)\ **Post date:** [July 12, 2016, 3:28pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/1 "2016-07-12T15:28:19Z")
The bane of the Straight Dope is those little factoids someone told us years ago that we never questioned, or even heard elsewhere one way or another, so let me get to the point. A buddy of mine from decades ago once claimed that turning a light on and off during the course of uses more electricity/costs more money than just leaving the light on during waking hours. (Mind you, this was back in the 70s, before these freakishly long-lasting light bulbs he have now were invented.) Is it even remotely possible that this is true? My dad was of the “Turn the lights off when you’re not using them” stripe and that’s always been my inclination. ---
**Author:** ![Me\_Billy](https://avatars.discourse-cdn.com/v4/letter/m/e480ec/32.png) [@Me\_Billy](https://boards.straightdope.com/u/Me_Billy)\ **Post date:** [July 12, 2016, 3:35pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/2 "2016-07-12T15:35:36Z")
Some industrial/commercial lights are like that to a limited extent. But for a home these days, shutting off lights when not in use will save the most electricity. Replace all your bulbs with LED bulbs and you will save even more! ---
**Author:** ![running\_coach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/running_coach/32/15836_2.png) [@running\_coach](https://boards.straightdope.com/u/running_coach)\ **Post date:** [July 12, 2016, 3:47pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/3 "2016-07-12T15:47:46Z")
Mythbusters did that as a [MiniMyth.](http://www.discovery.com/tv-shows/mythbusters/videos/lights-on-or-off-minimyth/) [Summary](http://www.curiousread.com/2007/11/myth-busters-leave-lights-on-or-turn.html) > [@](#): > > The answer is…according to the MythBusters show: “Yes there is a spike when you flip the switch on but it is in no way significant enough to be considered money saving to leave your lights on for a few minutes while you leave the room. So it is best to turn off your lights even for a few minutes, than to leave them running fearing the spike in energy and a spike in your electricity bill. Also if you were to use energy saving bulbs in the bathroom and were constantly flicking them on and off you would have to replace them sooner and in the end you be paying more for the bulbs than your month’s electric bill.” ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [July 12, 2016, 3:52pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/4 "2016-07-12T15:52:41Z")
I remember reading that in Canada, where electricity was cheap (at the time) many office blocks left all their light on 24/7 because the fluorescent tubes lasted longer and replacing them was the more expensive option. At home, I used to have two fluorescent tubes in the kitchen, and left them on all evening on the (probably mistaken) belief that it was somehow ‘better’. I now have LED tubes which not only give out a huge amount more light for the money, but don’t have that horrible flickering you get with fluorescents. Naturally, these are left off as much as possible. In fact, all the lights in our house, apart from the tube in the garage and the lamp in the loft (both not used much) are LEDs. ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [July 12, 2016, 4:00pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/5 "2016-07-12T16:00:38Z")
> [@bob\_2](#): > > I remember reading that in Canada, where electricity was cheap (at the time) many office blocks left all their light on 24/7 because the fluorescent tubes lasted longer and replacing them was the more expensive option. [Cecil made this point back in 1980.](http://www.straightdope.com/columns/read/222/to-save-energy-should-you-turn-lights-off-or-leave-them-on) [QUOTE=The Straight Dope] At one time, manufacturers strongly advised against switching fluorescent fixtures on and off frequently because you could reduce tube life as much as 20 percent. Downtown office buildings once left their lights on all night on the theory that it was cheaper to burn the extra juice than send a maintenance worker around every few months to change the tubes. However, the 70s saw the introduction of longer-lasting, rapid-start tubes that last for 20,000 hours, as opposed to 10-12,000 with the old ones. These you can flick on and off a little more casually, since you’ll only be reducing tube life from 5 to 10 percent. [/QUOTE] Of course, that column was written long before modern LED lights, or even today’s fluorescents. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [July 12, 2016, 6:50pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/6 "2016-07-12T18:50:07Z")
For fluorescents, you still don’t want to turn the light off and on casually. It not only shortens the life of the tube but also the life of the ballast.\* Even with today’s fixtures. The break even point is somewhere around 20 to 30 minutes. If you’re going to need the light before then, leave it on. - The ballast thing is only applicable for non-compact light fixtures. ---
**Author:** ![Vicsage](https://avatars.discourse-cdn.com/v4/letter/v/e68b1a/32.png) [@Vicsage](https://boards.straightdope.com/u/Vicsage)\ **Post date:** [July 12, 2016, 7:01pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/7 "2016-07-12T19:01:26Z")
Hope you all bought your LEDs years ago, because I fear the newer ones won’t last near as long. There’s little money to be made in making a bulb last 20 years. And since the price on LEDs has dropped considerably over the last years, companies would go out of business once everyone switches over. When incandecent bulbs first came out, they lasted much longer. Companies reduces the thickness of the filament to shorten life and sell more. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [July 12, 2016, 7:19pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/8 "2016-07-12T19:19:44Z")
> [@Vicsage](#): > > Hope you all bought your LEDs years ago, because I fear the newer ones won’t last near as long. There’s little money to be made in making a bulb last 20 years. And since the price on LEDs has dropped considerably over the last years, companies would go out of business once everyone switches over. When incandecent bulbs first came out, they lasted much longer. Companies reduces the thickness of the filament to shorten life and sell more. All the name-brand ones have the same warranty as they did three years ago. For example, Cree has a 5-year 100% satisfaction guarantee. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [July 12, 2016, 7:37pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/9 "2016-07-12T19:37:26Z")
> [@Vicsage](#): > > Hope you all bought your LEDs years ago, because I fear the newer ones won’t last near as long. There’s little money to be made in making a bulb last 20 years. This is conspiracy theory stuff. If mfrs aren’t making long-lived bulbs, it’s because no customer wants to pay what it costs to make them. If customers _are_ willing to pay for long-lived bulbs, then _somebody_ will make them, unless the entire industry is engaged in deliberate, illegal collusion; no single manufacturer will unilaterally decide not to make long-lived bulbs if that’s what the market truly wants and is willing to pay for. ---
**Author:** ![Vicsage](https://avatars.discourse-cdn.com/v4/letter/v/e68b1a/32.png) [@Vicsage](https://boards.straightdope.com/u/Vicsage)\ **Post date:** [July 12, 2016, 7:54pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/10 "2016-07-12T19:54:48Z")
I hope you’re right, but money talks and there’s no long term profit in making a product that lasts a very long time. You hook them on your product to drop the other products, then once you’ve got them, make the switch to an inferior product. As to guarantees, I haven’t read the small print, but I’d bet you’d need a proof of purchase of some kind and most people don’t hold on to proof of purchases of low price items for any length of time. ---
**Author:** ![running\_coach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/running_coach/32/15836_2.png) [@running\_coach](https://boards.straightdope.com/u/running_coach)\ **Post date:** [July 12, 2016, 7:59pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/11 "2016-07-12T19:59:50Z")
Just because. [Livemore Lightbulb](http://www.centennialbulb.org/). > [@](#): > > the Centennial Bulb, the Longest burning Light Bulb in history. Now in its 114th year of illumination. More exciting than the [Pitch Drop](https://en.wikipedia.org/wiki/Pitch_drop_experiment)! ---
**Author:** ![Vicsage](https://avatars.discourse-cdn.com/v4/letter/v/e68b1a/32.png) [@Vicsage](https://boards.straightdope.com/u/Vicsage)\ **Post date:** [July 12, 2016, 8:07pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/12 "2016-07-12T20:07:12Z")
If you doubt this has been done before, look up the Phoebus cartel. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [July 12, 2016, 8:28pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/13 "2016-07-12T20:28:15Z")
> [@Vicsage](#): > > I hope you’re right, but money talks and there’s no long term profit in making a product that lasts a very long time. You hook them on your product to drop the other products, then once you’ve got them, make the switch to an inferior product. And then your company withers when a competitor arises and offers the long-lived product that your company refused to produce. Witness [the demise of the Phoebus Cartel.](https://en.wikipedia.org/wiki/Phoebus_cartel#Demise) Hopefully some business/economics experts will chime in, but I assume that an arrangement like the Phoebus Cartel would be illegal under modern [competition laws.](https://en.wikipedia.org/wiki/Competition_law) Not to say it wouldn’t happen, but participants in a covert scheme that stifles free-market competition would be risking jail time, as [these guys found out.](http://www.wthr.com/story/6068215/three-managers-sentenced-in-concrete-price-fixing-scheme) LED lighting is an example of [disruptive innovation.](https://en.wikipedia.org/wiki/Disruptive_innovation) If there’s not enough money to be made in selling long-lived light bulbs, then the answer is that some of the manufacturers will die, and the remaining few will gain market share; the trend will continue until the total sales for each of the remaining manufacturers is enough to sustain them. ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [July 12, 2016, 10:32pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/14 "2016-07-12T22:32:59Z")
> [@bob\_2](#): > > I remember reading that in Canada, where electricity was cheap (at the time) many office blocks left all their light on 24/7 because the fluorescent tubes lasted longer and replacing them was the more expensive option. > > At home, I used to have two fluorescent tubes in the kitchen, and left them on all evening on the (probably mistaken) belief that it was somehow ‘better’. I now have LED tubes which not only give out a huge amount more light for the money, but don’t have that horrible flickering you get with fluorescents. Naturally, these are left off as much as possible. In fact, all the lights in our house, apart from the tube in the garage and the lamp in the loft (both not used much) are LEDs. While there might be something to that, in my office building the explanation was very simple. There was a construction budget and it was very limited. So to save money, they skipped light switches in the offices and used a 350 volt supply that wired three fluorescents in series (each off had six fluorescents). They turned them off late in the evening and turned them all on in the morning. It wasn’t to save operating cost; it was to save building cost. If I wanted to come late at night or on a weekend, I would have to go the circuit box and flick the switch that turned on my office and maybe a half dozen others. When I left I didn’t flick them off because, who knows, someone else might have come in in the meantime and I would be plunging them into darkness. Eventually, they added light switches. But what they had to was use the switch to turn a relay to turn on the lights in each office because it was against code to run 350 volts to a wall switch. Later on they replaced all the switches by new ones that included motion sensors that turned the lights off after 15 motionless minutes. I am capable of sitting just thinking for 15 minutes. But if my office goes dark all I have to do is wave my arm and the lights go back on. Shows the value of short term thinking. But the building committee had just one budget and operating (or retrofitting) costs just weren’t in their remit. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [July 12, 2016, 10:53pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/15 "2016-07-12T22:53:26Z")
> [@Vicsage](#): > > I hope you’re right, but money talks and there’s no long term profit in making a product that lasts a very long time. You hook them on your product to drop the other products, then once you’ve got them, make the switch to an inferior product. As to guarantees, I haven’t read the small print, but I’d bet you’d need a proof of purchase of some kind and most people don’t hold on to proof of purchases of low price items for any length of time. That’s their problem, not mine. I save all my LED proof-of purchases, stapled to the receipt, and then write the date the lamp was installed on the base with a Sharpie. ---
**Author:** ![Orwell](https://avatars.discourse-cdn.com/v4/letter/o/dfb087/32.png) [@Orwell](https://boards.straightdope.com/u/Orwell)\ **Post date:** [July 13, 2016, 3:05pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/16 "2016-07-13T15:05:40Z")
> [@beowulff](#): > > That’s their problem, not mine. > I save all my LED proof-of purchases, stapled to the receipt, and then write the date the lamp was installed on the base with a Sharpie. And what happens when the store no longer replaces the bulb, or even carries the same model? If you read the warranties, most require you to ship the bulb back to the manufacturer for replacement. Are you really going to do that for a bulb that quits working a year or two or three from now? I’ve had many CREE LED bulbs go bad, and Home Depot has been great about replacing them with no fuss, no muss. But as time goes on, I am sort of waiting for the response “we don’t replace those any more; you have to send in the old bulb to CREE”. At that point, I’ll be upset, but I doubt I’ll box up a bulb and pay postage to send it back. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [July 13, 2016, 3:15pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/17 "2016-07-13T15:15:51Z")
> [@Orwell](#): > > And what happens when the store no longer replaces the bulb, or even carries the same model? If you read the warranties, most require you to ship the bulb back to the manufacturer for replacement. Are you really going to do that for a bulb that quits working a year or two or three from now? > > I’ve had many CREE LED bulbs go bad, and Home Depot has been great about replacing them with no fuss, no muss. But as time goes on, I am sort of waiting for the response “we don’t replace those any more; you have to send in the old bulb to CREE”. At that point, I’ll be upset, but I doubt I’ll box up a bulb and pay postage to send it back. It all depends on the replacement cost. ---
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [July 13, 2016, 4:37pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/18 "2016-07-13T16:37:56Z")
> [@Vicsage](#): > > I hope you’re right, but money talks and there’s no long term profit in making a product that lasts a very long time. You hook them on your product to drop the other products, then once you’ve got them, make the switch to an inferior product. As to guarantees, I haven’t read the small print, but I’d bet you’d need a proof of purchase of some kind and most people don’t hold on to proof of purchases of low price items for any length of time. You act as if all the light bulb receptacles that will exist throughout the next 20 years are already out in the market with a bulb in it. This just isn’t the case. There are new homes and offices being built every single day. All of these new buildings are going to need new light bulbs. To say that a company that sells long lasting light bulbs will go out of business once everyone buys their bulbs is ridiculous. The demand for new bulbs is not just related to the failure rate of old bulbs, it is also dependent on the production of new fixtures and buildings. That’s as insane as people who make similar claims with automobiles. CT nutters claims that if a company makes a car that lasts a long time, they will be out of business once everyone buys their cars, since the cars will never break. That completely ignores the fact that hundreds of thousands of people are getting their licenses every year or otherwise needing a car they didn’t need before. The demand grows as the population and market grows. Why do you think companies are still able to sell chairs? I mean, according to your theory, nobody should be buying new wooden chairs since they easily last for 50 years. Right? Or lamps, for that matter. When does a lamp ever break? It’s usually the bulb that goes out. Lamps last forever. So there’s no way any lamp company could possibly stay in business, right? ---
**Author:** ![MacLir](https://avatars.discourse-cdn.com/v4/letter/m/9e8a1a/32.png) [@MacLir](https://boards.straightdope.com/u/MacLir)\ **Post date:** [July 14, 2016, 2:15pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/19 "2016-07-14T14:15:02Z")
Let me throw another twist into this. The building I work in has fluorescent lights in most of the enclosed offices, but mainly incandescent lamps for general illumination in the open areas (cube farms). Turning them off manually is discouraged (especially in cold weather) because the heat generated is calculated into the climate control. (Some are on circuits that turn off in the wee hours and back on for work hours.) ---
**Author:** ![Orwell](https://avatars.discourse-cdn.com/v4/letter/o/dfb087/32.png) [@Orwell](https://boards.straightdope.com/u/Orwell)\ **Post date:** [July 14, 2016, 2:30pm UTC](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724/20 "2016-07-14T14:30:03Z")
> [@MacLir](#): > > Let me throw another twist into this. > > The building I work in has fluorescent lights in most of the enclosed offices, but mainly incandescent lamps for general illumination in the open areas (cube farms). Turning them off manually is discouraged (especially in cold weather) because the heat generated is calculated into the climate control. (Some are on circuits that turn off in the wee hours and back on for work hours.) The “wasted” energy in any type of lighting is thrown off as heat. And, certainly, leaving lights on in the winter adds heat to the building, which can be viewed as a benefit. While some of the heat radiates downward to the occupied space, some of it goes up above the drywall or suspended ceiling and does not benefit occupants. But, certainly, leaving lights on during the heating season is better than leaving them on during the cooling season, where the wasted heat has to be removed by air conditioning. If your building is actually dependent on byproduct heat from lighting, it sounds like the heating system is undersized. I can’t imagine it makes sense to keep incandescent lights for the byproduct heat, since HVAC systems are more efficient at heating space than lights, but it is certainly a short-term strategy. If you are using incandescent lights, you are likely either wasting light or wasting heat, depending on the weather and time-of-day occupancy. [Next page](https://boards.straightdope.com/t/cheaper-to-leave-the-lights-on/759724.md?page=2)