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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> Energy/Power Usage https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1250157467 Message started by Sandy on Aug 13^th, 2009, 10:57am

Title: Energy/Power Usage
Post by Sandy on Aug 13^th, 2009, 10:57am

Hi All,

Just wondering if anyone can assist with a debate in our office. We're about to run a Energy/Recycling campaign and the subject of turning electrical appliances off (obviously when not in use, not because we can't be ars3d working) has come up as a topic.

There are the obvious appliances like printers, copiers, coffee machines etc that we can turn off by use of timers, but the biggest issue are our LCD monitors. There's approx 750/800 in total, which predominantly are left on (standby) overnight and over the weekend.

Once the base unit or laptop has been powered down, the monitor goes on to standby. 99% of them are used between 08:00 - 17:00hrs Mon - Fri, so in use for 9hrs per day, then on standby for the other 15hrs a day and ALL weekend. The questions therefore are:

1) Given that as there is heat being given off by them all even in standby mode, then there is still power being used somehow. Are there different amounts of power/energy being consumed when in use and in standby?
2) If so, is there a way of calculating it? (I've tried contacting Dell, but no one seems to want to help out).
3) There are thoughts that some LCD's/plasmas etc should be left on standby, but does any one if this is just idle chat or is there some reasoning behind it?

Any thoughts/good points gratefully accepted.

Thanks.

Sandy.

Title: Re: Energy/Power Usage
Post by londonman on Aug 13^th, 2009, 12:15pm

Why not buy one of those 13A plug-in energy monitors from maplin - or even a couple - and then plug your vdu's etc into them and measure the results.

Title: Re: Energy/Power Usage
Post by big_all on Aug 13^th, 2009, 1:33pm

yep i would definatly get a flow meter as the consumption on stanby could be anywhere between 3 and 30% it will vary from manufacturer to manufacturer

why not set up the power managment to turn off the computer after say 90 mins

also get those socket extensions that have a primery socket and when say the tower powers down all the sockets go dead turning off your screen printer speakers ect

Title: Re: Energy/Power Usage
Post by CWatters on Aug 14^th, 2009, 8:58am

Google the make/model number and "standby power consumption" and you may find someone has already measured it. The data for my Samsug 226cw was 45W operating, 1W standby. You can also look for the Energy Star logo. Any without that should be investigated further.

Some of the plug in power meters don't seem to be very accurate at measuring low power levels? I was surprised to discover that my PC consumes quite a bit of power power even when switched off using the switch I/O on the power supply at the back. I had assumed that this switch was the first thing in the power supply apart perhaps from some RFI filter capacitors. I can only assume that there is a power factor issue or something like that messing with the readings. I haven't investigated further yet.

I doubt there is a good reason to leave an LCD illuminated as the weak point is probably the flourescent back light or capacitors in the backlight power supply. These tend to have relatively short life expectancy. Likewise I doubt there is any advantage in keeping them in standby mode.

Edit: There is a new Energy star spec for LCD monitors manufactured after the end of this year:

http://www.energystar.gov/index.cfm?fuseaction=find_a_product.ShowProductGroup&pgw_code=MO

Quote:

In Sleep Mode, computer monitor models must consume 2 watts or less.

In Off Mode, computer monitor models must consume 1 watt or less

My guess is that most monitors manufactured recently already meet that or they wouldn't introduce it.

Title: Re: Energy/Power Usage
Post by Sandy on Aug 14^th, 2009, 11:16am

CWatters - Good call. Google had just the answer. Didn't twig with me to put that into a search engine. The wonders of the WWW eh!

Londonman - Might just try a couple of the plug in energy monitors as I can also use them on other appliances when I'm done.

Big_all - Power Management. Might have to contact my IM/IT dept about that one. I've got it set up at home but, not sure how they'd go about setting it up on that many PC/laptops. Socket extentions, hmm, love to, but they've already told me that if it costs, do without!

Thanks for the advice. It give me more direction on this subject.

Title: Re: Energy/Power Usage
Post by CWatters on Aug 14^th, 2009, 5:57pm

Biggest saving probably comes from turning off desktop computers and office lighting at night. Perhaps speak to your IT deptment about shutting the PC down down automatically after backups and Windows updates are completed.