What is more economical- leaving things on or turning them off in short spurts?

moneymaker2010

This one has been on my mind for a bit so interested if someone can clear it up for me.

My mum told me recently that when you turn a light on it causes a power surge such that turning a light on for a little and off again would cause more elec. usage than if you just left it on in between these bursts to prevent the surge each time.

I have also been told the same about turning your computer on and off. I often have alot of (computer) windows open as I use my computer throughout the day. Most days I will go out to do shopping and other errands which takes me usually no more than an hour. I sometimes leave the computer on if I have alot of work open instead of turn it off for convenience and due to the power thing. If I plan to be out more than an hour I'll turn it off.

How much power do I save by turning it off?

I do hate to be wasteful but it seems kind of silly turning it off if I only go out for a few mins. then have to boot everything back up again.

I was just about to pop out which is what reminded me to write this up .

Thoughts?

HappyMJ

For a computer it's the convenience factor. Do you have a suspend function? I'd use that.
For lights the power used to start the lamp will be about the same it it would use in 1 second. So don't turn it off then straight back on again. More than 1 second out of the room then you'll save. But we are talking about something that costs a fraction of a penny per hour to run. A 13W CFL costs about 2 tenths of a penny per hour to run. It's hardly a saving. You could run it for 5 hours for a penny.

moneymaker2010

Hah, ok thanks. that is one less thing to worry about then.

Ye I'll look into the sleep thing for the comp. but my current regimen I think will suffice of leaving on if less than an hour i.e 3 0 mins or so and off if more than an hour. I do always switch the monitor off before leaving.

How much elec/cost would a comp use per hour?

HappyMJ

moneymaker2010 wrote: »

Hah, ok thanks. that is one less thing to worry about then.

Ye I'll look into the sleep thing for the comp. but my current regimen I think will suffice of leaving on if less than an hour i.e 3 0 mins or so and off if more than an hour. I do always switch the monitor off before leaving.

How much elec/cost would a comp use per hour?

Look at it's rating and half it. i.e 100W power supply usually uses about 50W of power during normal use then multiply that by your electric rate lets say 14p. So 0.050 * 0.14 = 0.7p per hour.

Anything that involves heat is the real killer on an electric bill. Electric heating 28p/hour. Dryer 14p/hour. and so on....

Pincher

You are actually using around 100 to 200W when it's on.
Don't forget the monitor.

So I would expect 200W if you leave both on. Ten hours would be 2kWh, at 10p per kWh, 20p.

HappyMJ

Pincher wrote: »

You are actually using around 100 to 200W when it's on.
Don't forget the monitor.

So I would expect 200W if you leave both on. Ten hours would be 2kWh, at 10p per kWh, 20p.

I leave mine on 24 hours a day (server) and my bill does not come to that...ouch if it did. Imagine that 24 hours 365 days = £175 per year. No, the energy monitor says it's about 50W so it's much less at about £1 per week.

samtheman1k

Use the standby or hibernate function, and turn the monitor off. Or just buy a computer with a proper OS that is quicker to boot up.

Parva

samtheman1k wrote: »

Use the standby or hibernate function, and turn the monitor off. Or just buy a computer with a proper OS that is quicker to boot up.

Ouch! Batten down the hatches, it's OS wars! I personally just flick the power off when my PC shuts down, my energy monitor tells me that I'm saving an extra 36 watts when I do. It all adds up.

Cardew

moneymaker2010 wrote: »

My mum told me recently that when you turn a light on it causes a power surge such that turning a light on for a little and off again would cause more elec. usage than if you just left it on in between these bursts to prevent the surge each time.

Shouldn't say this but your Mother is wrong about lights with regards to saving money.

It is an urban myth that has its origin in the days of the old fluorescent lights that do have a small surge for a fraction of a second.

However for all practical purposes you can ignore this tiny amount of extra electricity.

There is a thought that constantly switching lights on/off shortens their life.

With regard to computers, simply use the 'sleep' or 'hibernate' function - that's their purpose.

moneymaker2010

ok cheers.