BOB.T

We've had air con installed in our office and our boss has taken to turning it off whilst we're out of the office for an hour at lunch

How much money will this save, we think some where between **** all and the far end of a fart? :suspiciou

We don't know how much power it uses but we heard 4kw being mentioned Also, it's running flat out now to cool the office to the pre lunch chill that we like

Cheers!

PS, he's gone out now, should we turn his pooter off, he's left the lights on in his office too!

Suresh

You boss is a penny-pinching tool. I would expect the unit is much more expensive and less efficient whilst on full-power after lunch than running permantantly at a normal level.

Given how he knows how to cut costs without understanding anything about adding value, my guess would be that he's a qualified accountant!

Suresh

BlkKnight

I'd hazzard a guess to say over that time scale it would cost more to re-chill the room depending on how high the ambient temp climbed above the desired temperature.

You would probabily save more money by leaving the AC on and turning off all your PC monitors while you were out.

With A/C the biggest saving can be made by KEEPING THE WINDOWS SHUT, it really annoys me to see people with the AC on full wack and their windows open cooling the planet . . . .

/edit

Lights on the other hand- depending on type are different.

If it's flouresent (sp) tubes, they have to be turned off for more than 3 hours to actually see any cost saving due to the high energy cost of turning them on. Same applies to "energy efficient" bulbs.

If it's normal bulbs this does not apply.

/edit 2 I'm not a beancounter - honest

The Zohan

LMFAO!

Angry

Spot on. The energy used to re-cool the room back down to the temp it was at before the unit was turned off will greatly outweigh the energy used to maintain that temp over your lunch hour.

Our boss is a total bean counter(understandable as we are hovering around break even) and asked the very same questions of the A/C engineer.

Dieseldog

Suggest to him you all wear Petzl headtorches with the office lights turned off in winter...

Honestly, the guy shouldn't be a manager if this is what keeps him occupied

carl

So why don't people leave their central heating on overnight?

Angry

Because most people are tucked up in their warm beds at night and would get quite hot with the radiators on too?

In our house we have the stat set to turn off at 11pm and goes back on at 5am, an hour before anyone gets up.

Suresh

Some of us do.
Our house thermostat is programmed to switch to "ECO" mode at night (and when we are away) which keeps the temperature above 15 oC rather than above 21 oC otherwise.

corradoboy

I used to have a real pennypinching wnaker of a boss when I was an apprentice at 16. He bo11ocked me dozens of times for leaving my shiner (illuminated desk for photographic film work) on when I left at night. In actual fact I very rarely left it on, but others used it in my absence as it was directly outside the darkroom (and yes, they probably enjoyed watching me get the bo11ocking ). When a mate who worked for a major electrical component supplier told me about the consumption characteristics of flourescent tubes I spent the next year switching mine off at every single opportunity Probably 50-60 times a day At 3 hours usage a time, I can now see why the tw@t went bust In a normal week I'd have used it for 38 hours and switched it on 5 times. I still only used it during the 38 hours, but it's consumption will have equated to 900 hours a week. Stick that in your pipe and smoke it Stringer and Stockwell

BOB.T

Thanks guys!

anskills

i would expect more like 8-9kw depending on office size of course though

AndyC_772

iTrader: (2)

How do you work that one out? The a/c system still ultimately has to pump out all the heat that enters the room over lunchtime, whether it's actually switched on while you're at lunch or not.

However, as the room warms up, the rate at which it gains heat reduces - so the total heat entering the room is less, and therefore the total that has to be pumped back out again is less. There is indeed an energy saving by switching it off.

Doesn't stop your boss being a tool, though

carl

But as the aircon pumps harder it generates more of its own heat...

And I bet the relationship between "amount of pumping" and input power isn't linear either.

Brit_in_Japan

[engineer mode]
If you analyse it logically, it probably does save energy (=money). Heat flow into the building from outside is proportional to the temperature difference. So as inside temperature increases, less "heat" enters the building which needs to be cooled. So even if the air-con has to work harder following a lunch hour switch off, the total energy it would take to return the temperature back to the original value would be less than if you left the air-con on all the time.

Extrapolate to extremes to see the logic. Assuming constant outside temperatures, if you left the air-con switched on for 2 weeks, would it take more or less energy than if you switched it off and switched it back on 2 weeks later and waiting for the building to cool?

Extrapolate to 2 months or 2 years, whatever, the logic is the same as if for 1 hour.

One assumption needed to make the above true is that the efficiency of the AC system needs to be constant at different workloads, but let's not go there...
[/engineer]

In Japan this summer to reduce air-con costs they launched the "coolbiz" initiative. In return for setting a recommended air-con temperature of 28 deg C, employers have been encouraged to let their staff take their jackets off and remove their ties. This is heady stuff for Japan !!!

pmarch

Agree on the AC and keeping windows closed. But where did you get your info. on fluorescent tubes using three hours worth of power on start-up?

Angry

Just going by what the A/C engineer said.

BOB.T

Are we safe to say in terms of money it's **** all?