Are bathroom motion sensors really more cost effective than signs?

[Eeezee]

Motion sensors take up some power... I'd be willing to bet that the bathroom lights used in most modern buildings are low-power, but probably suck up more juice than a few motion sensors. Net gain, right?

Couldn't a simple sign reminding people to turn out the light if they're the last one there probably save more money than a motion sensor that's on perpetually? That means the lights are actually on for less time overall if everyone actually turns off the lights. And then you don't have motion sensors sucking up power, either!

Or what if you just have a janitor turn off the lights at night? In larger office buildings, aren't the motion sensors going to be useless for most of the day because the bathrooms are constantly in use? I'd guess that in a big office building, the bathroom lights won't be turned off for more than an hour in total during the work day, and then the lights remain off all night. Does an hour of light use more energy than 24 hours of motion sensors in operation?

 

[Cogman]

Originally posted by: Eeezee
Motion sensors take up some power... I'd be willing to bet that the bathroom lights used in most modern buildings are low-power, but probably suck up more juice than a few motion sensors. Net gain, right?

Couldn't a simple sign reminding people to turn out the light if they're the last one there probably save more money than a motion sensor that's on perpetually? That means the lights are actually on for less time overall if everyone actually turns off the lights. And then you don't have motion sensors sucking up power, either!

Or what if you just have a janitor turn off the lights at night? In larger office buildings, aren't the motion sensors going to be useless for most of the day because the bathrooms are constantly in use? I'd guess that in a big office building, the bathroom lights won't be turned off for more than an hour in total during the work day, and then the lights remain off all night. Does an hour of light use more energy than 24 hours of motion sensors in operation?

Nah. Motion sensors require almost no power to run (Yes I know, more then nothing). Not only that, but people are dumb. You may leave a sign there but I can guarantee that 50% of people will ignore it and leave the lights on.

Leaving those lights on for an hour can easily negate the cost of the motion sensor running for a month. One site I went to rated their motion sensors at about 1 Watt. considering most bathrooms have at least 2 60W fluorescent tubes (At LEAST, many have much more) I would say the savings is worth it.

 

[blurredvision]

My work has signs in the stalls that says to wipe the seat and flush the toilet before exiting.....nobody ever does that, so I wouldn't expect anyone to turn the light out.

 

[mugs]

Yeah, people are going to pay attention to the sign. :laugh:

Problem is, everyone would have to check all of the stalls to see if anyone is in the bathroom before they leave, and the handicap stall door closes automatically.

 

[Jeff7]

What about the resulting loss of life from constantly power-cycling fluorescent tubes? They really take a hit in longevity with each power-up, though new ballasts might reduce this effect. Older ballasts were magnetic, and look like they have a capacitor and a transformer for startup. There are electronic ballasts, which are more efficient in terms of power use. I don't know what they do to bulb life though, since they tend to be instant start.
I have also seen "programmable ballasts," which seem to be better at prolonging bulb life.

But I'm no expert on these matters.

 

[Eeezee]

Originally posted by: Cogman

Originally posted by: Eeezee
Motion sensors take up some power... I'd be willing to bet that the bathroom lights used in most modern buildings are low-power, but probably suck up more juice than a few motion sensors. Net gain, right?

Couldn't a simple sign reminding people to turn out the light if they're the last one there probably save more money than a motion sensor that's on perpetually? That means the lights are actually on for less time overall if everyone actually turns off the lights. And then you don't have motion sensors sucking up power, either!

Or what if you just have a janitor turn off the lights at night? In larger office buildings, aren't the motion sensors going to be useless for most of the day because the bathrooms are constantly in use? I'd guess that in a big office building, the bathroom lights won't be turned off for more than an hour in total during the work day, and then the lights remain off all night. Does an hour of light use more energy than 24 hours of motion sensors in operation?

Nah. Motion sensors require almost no power to run (Yes I know, more then nothing). Not only that, but people are dumb. You may leave a sign there but I can guarantee that 50% of people will ignore it and leave the lights on.

Leaving those lights on for an hour can easily negate the cost of the motion sensor running for a month. One site I went to rated their motion sensors at about 1 Watt. considering most bathrooms have at least 2 60W fluorescent tubes (At LEAST, many have much more) I would say the savings is worth it.

Ah, those numbers are interesting. Clearly motion sensors are the way to go. I had no idea that they used so little power.

Thanks

 

[nakedfrog]

Yeah, I'm gonna let a piece of stamped metal nailed to the wall tell ME what to do.

 

[Cogman]

Originally posted by: Eeezee

Originally posted by: Cogman

Originally posted by: Eeezee
Motion sensors take up some power... I'd be willing to bet that the bathroom lights used in most modern buildings are low-power, but probably suck up more juice than a few motion sensors. Net gain, right?

Couldn't a simple sign reminding people to turn out the light if they're the last one there probably save more money than a motion sensor that's on perpetually? That means the lights are actually on for less time overall if everyone actually turns off the lights. And then you don't have motion sensors sucking up power, either!

Or what if you just have a janitor turn off the lights at night? In larger office buildings, aren't the motion sensors going to be useless for most of the day because the bathrooms are constantly in use? I'd guess that in a big office building, the bathroom lights won't be turned off for more than an hour in total during the work day, and then the lights remain off all night. Does an hour of light use more energy than 24 hours of motion sensors in operation?

Nah. Motion sensors require almost no power to run (Yes I know, more then nothing). Not only that, but people are dumb. You may leave a sign there but I can guarantee that 50% of people will ignore it and leave the lights on.

Leaving those lights on for an hour can easily negate the cost of the motion sensor running for a month. One site I went to rated their motion sensors at about 1 Watt. considering most bathrooms have at least 2 60W fluorescent tubes (At LEAST, many have much more) I would say the savings is worth it.

Ah, those numbers are interesting. Clearly motion sensors are the way to go. I had no idea that they used so little power.

Thanks

Np. When I was looking up the numbers for a motion sensors power usage I found one that a company rated at 20 nW per pixel, or some insanely low number like that. Though it was advertised as an ultra low power motion detector and I don't think it was used for bathroom lights .

 

[krunchykrome]

the problem isnt the sign

the problem is people dont want to touch things in the bathroom

 

[sdifox]

fluorescent is only energy efficient to run long continuous period of time. Turning it on and off is actually costing more money.

 

[0roo0roo]

well its obvious why, watch, half the dudes dont wash their hands.

 

[Cogman]

Originally posted by: sdifox
fluorescent is only energy efficient to run long continuous period of time. Turning it on and off is actually costing more money.

not really. Fluorescent bulbs consume almost the exact same amount of energy when they are turning on as when they have been running for hours. They don't instantly give out maximum light, but that is really a moot point. The only place where it would get more expensive is when you start talking about wearing down the bulbs faster. Then you might have a point.

Even then, the bulb can last quite a long time with continuous on/off cycles.

http://cr4.globalspec.com/thre...luorescent-Tube-Lights

Read some of the posts, they explain in more detail what I just said.

 

[Newbian]

Originally posted by: sdifox
fluorescent is only energy efficient to run long continuous period of time. Turning it on and off is actually costing more money.

That's not true.

It only works out that way if you don't plan on leaving the light on for 3 or so minutes at a time.

 

[Throckmorton]

Originally posted by: Cogman

Originally posted by: sdifox
fluorescent is only energy efficient to run long continuous period of time. Turning it on and off is actually costing more money.

not really. Fluorescent bulbs consume almost the exact same amount of energy when they are turning on as when they have been running for hours. They don't instantly give out maximum light, but that is really a moot point. The only place where it would get more expensive is when you start talking about wearing down the bulbs faster. Then you might have a point.

Even then, the bulb can last quite a long time with continuous on/off cycles.

http://cr4.globalspec.com/thre...luorescent-Tube-Lights

Read some of the posts, they explain in more detail what I just said.

Mythbusters busted that myth.

 

[Jeff7]

Originally posted by: sdifox
fluorescent is only energy efficient to run long continuous period of time. Turning it on and off is actually costing more money.

It might cost more money, but only because of the cost of replacing the tubes more frequently - and for a business, that doesn't just mean parts costs, that also means paying a maintenance employee to install them.
Philips standard Alto T8 tubes are rated 20,000 hours for 3hrs per startup. But I believe that jumps to 30,000 hours for 12hrs per startup.

Yes, they will consume a lot of energy when starting, but it's only for a small fraction of a second, so the watt-hrs consumed for startup are very low.

 

[nakedfrog]

Originally posted by: Newbian

Originally posted by: sdifox
fluorescent is only energy efficient to run long continuous period of time. Turning it on and off is actually costing more money.

That's not true.

It only works out that way if you don't plan on leaving the light on for 3 or so minutes at a time.

Per Mythbusters (so it depends on how much you trust their methodology, but they did use a Killawatt and also set up bulbs on a circuit to repeatedly cycle them) a fluorescent bulb takes about 23 seconds equivalent running time electricity for startup.

 

[PlasmaBomb]

Originally posted by: blurredvision
My work has signs in the stalls that says to wipe the seat and flush the toilet before exiting.....nobody ever does that, so I wouldn't expect anyone to turn the light out.

ewwwwwwww

 

[0roo0roo]

Originally posted by: nakedfrog

Originally posted by: Newbian

Originally posted by: sdifox
fluorescent is only energy efficient to run long continuous period of time. Turning it on and off is actually costing more money.

That's not true.

It only works out that way if you don't plan on leaving the light on for 3 or so minutes at a time.

Per Mythbusters (so it depends on how much you trust their methodology, but they did use a Killawatt and also set up bulbs on a circuit to repeatedly cycle them) a fluorescent bulb takes about 23 seconds equivalent running time electricity for startup.

actually the problem is wearing out the light. they don't like being turned off and on all the time.

as for turn on speed, newer electronic ballasts are instant on basically.

 

[nakedfrog]

Originally posted by: 0roo0roo

Originally posted by: nakedfrog

Originally posted by: Newbian

Originally posted by: sdifox
fluorescent is only energy efficient to run long continuous period of time. Turning it on and off is actually costing more money.

That's not true.

It only works out that way if you don't plan on leaving the light on for 3 or so minutes at a time.

Per Mythbusters (so it depends on how much you trust their methodology, but they did use a Killawatt and also set up bulbs on a circuit to repeatedly cycle them) a fluorescent bulb takes about 23 seconds equivalent running time electricity for startup.

actually the problem is wearing out the light. they don't like being turned off and on all the time.

Bulb Longevity

They tested one final element of this myth: frequently turning lights on and off decreases their life span, thus leading to greater costs. Grant setup a timer and relay to turn the bulbs on and off repeatedly every 2 minutes. After six weeks, only the LED bulb was still working. Based on this test, they extrapolated that it would take five years of ordinary usage to cause the bulbs to burn out.

 

[OdiN]

Originally posted by: 0roo0roo

Originally posted by: nakedfrog

Originally posted by: Newbian

Originally posted by: sdifox
fluorescent is only energy efficient to run long continuous period of time. Turning it on and off is actually costing more money.

That's not true.

It only works out that way if you don't plan on leaving the light on for 3 or so minutes at a time.

Per Mythbusters (so it depends on how much you trust their methodology, but they did use a Killawatt and also set up bulbs on a circuit to repeatedly cycle them) a fluorescent bulb takes about 23 seconds equivalent running time electricity for startup.

actually the problem is wearing out the light. they don't like being turned off and on all the time.

as for turn on speed, newer electronic ballasts are instant on basically.

What does "instant on" have to do with how much electricity is used during the turning on phase?