How much electricity does your home IT use?

This content is 16 years old. I don't routinely update old blog posts as they are only intended to represent a view at a particular point in time. Please be warned that the information here may be out of date.

Last month I commented on minimising man’s effect on the planet and, whilst I’m in favour of reducing carbon emissions, much is being made of a few high-profile but relatively low-impact issues and governments are doing little to tackle the little things that can really make a difference.

One of those things we can all do is to examine the amount of electricity that we use – because there is direct link between electricity generation and carbon emissions (and, here in the UK, we have precious-little hydro- and solar-powered infrastructure so much is being made of wind, which is inefficient and variable, so still needs to be backed up with a firm source of energy – generally coal, gas or nuclear).

I imagine that, as IT administrators and enthusiasts, many of this blog’s readers have a collection of devices running a home IT infrastructure that would be more suitable for a small business. Back in January I bought a small server to migrate the workload away from my many PCs but my (capped rate) electricity bill has still risen – largely because I haven’t yet managed to move the workload away from the old kit that is destined to be turned off. Even if you don’t have a stack of IT kit running in your garage/cupboard-under-the-stairs-which-acts-as-the-home-data-centre, the chances are that you work from home sometimes – saving money and the reducing the emissions caused by travel – but distributing your employer’s energy usage across many homes (meanwhile the lights are still on and the air-con is still running back in the office).

So how much power does your IT use? Well, armed with a simple power monitor from Maplin, this is what I found:

Device Power (“on”) Power (“off”) Power (“standby”)
10 year-old PC (Compaq DeskPro EN6350: Pentium 3, 512MB RAM, 20GB HDD) 44W 5W
5 year-old PC (Compaq Evo D500: Pentium 4 1.7GHz, 512MB RAM, 20GB HDD) 50-100W 3-4W
Modern notebook PC (Apple MacBook: Intel Core 2 Duo 2.2GHz, 4GB RAM, 320GB HDD) 22W 1W
Server (Dell PowerEdge 840: Quad-core Intel Xeon 2.13GHz, 8GB RAM, 1.1TB storage) 100W 10W
15″ LCD Monitor 25W 1W 1W
20″ LCD monitor 42W 2W 2W
Inkjet all-in-one printer/fax/scanner/copier (HP OfficeJet 6310) 8W (16W when printing)
Laser printer (HP LaserJet 2200dn) 10W (600W when printing)
Fast Ethernet Switch (3Com 3300) 45W
Gigabit Ethernet Switch (Cisco 3750) 65W
Unmanaged Ethernet hub (NetGear EN108) 2W
Unmanaged Gigabit Ethernet switch (NetGear GS108) 5W
Desk lamp 25W 1W
Nokia mobile phone charger 3W 0W
24″ CRT Widescreen TV 80W (average) 2W 4W

MaplinI’m no electrical engineer but there are some surprises there for me. My mobile phone charger doesn’t use any power when it’s not charging (contrary to popular belief) but it seems my desk lamp does! Turning off my monitors at night seems to make no difference to their power draw, so I should really remove the plug from the socket (as should I for the TV). Meanwhile my recent switch from a laser printer to an inkjet might save some power (depending on the amount of printing I do) but what about the environmental cost of all those ink cartridges? As for the networking kit – my unmanaged switches are not only fanless (i.e. silent) but they use significantly less power too.

Of course, not all devices are equal. When I last visited my Grandmother, I was alarmed to find that her television was still “on” when it was on standby – the screen was off but I could still hear the sound being broadcast on the last channel she had been watching. And my 10-year-old Sony Trinitron Widescreen CRT TVs are probably more efficient than today’s 100Hz High Definition LCD displays – they’ll probably last longer too, which is why I’m not getting rid of them just yet.

As for that pile of PCs running a “data centre” in the garage, it seems that my new server is reasonably efficient in comparison but it will still draw 2.4kWh a day – at around £0.15 per unit (it’s not that simple because some units are charged at a lower rate than others) that’s costing me £0.36p a day. That doesn’t sound much until you realise that works out as £131 a year if the server is running 24×7 – and that equates to 0.377 tonnes of CO2 [source: Carbon Footprint]. It looks like I’d better get out and plant some more trees…

So, regardless of whether or not you believe in “green IT”, you can save some money by switching off some of this kit when it’s not in use. Modern operating systems have power-saving options – and technologies like Wake On LAN (WOL) allow us to bring a device back online when it is required. You need to apply some common sense too – turning off the VCR at the mains socket won’t let the device do what it is intended to do (i.e. record TV programmes) but does the microwave in the kitchen need to be on all the time just to run a digital clock (another 2W)?

If you can’t get your head around saving the planet – forget the “greenwashing” and think about saving some money instead.

3 thoughts on “How much electricity does your home IT use?

  1. One of those things we can all do is to examine the amount of electricity that we use – because there is direct link between electricity generation and carbon emissions.

  2. Turning off my monitors at night seems to make no difference to their power draw, so I should really remove the plug from the socket.

  3. Facts about electricity !
    Hi, my real comment is quiet simple. I have try some DIY to produce green energy and to safe money. Some works, some don’t. Here I just give you some personnals impressions of what is good, after trying it.
    For exemple Tesla method is great for electricity. But there is more, for Solar for exemple. Just have a look on My Blog
    And please give comments about your own experiences !
    Paul Sebastian

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