Scan's TekSpek

Our Aim
To provide you with an overview on New And existing technologies, hopefully helping you understand the changes in the technology. Together with the overviews we hope to bring topical issues to light from a series of independent reviewers saving you the time And hassle of fact finding over the web.

We will over time provide you with quality content which you can browse and subscribe to at your leisure.

TekSpek Guides
Energy Efficiency

Energy Efficiency

Date issued:

The Background
In recent years the cost of electricity has gone up by a far greater degree than inflation, and such is the financial and environmental impact of its consumption, that most PC-related companies are looking at ways of reducing power-consumption across the range of products. Being green, then, is just good.

Recently, closer to our hearts, NVIDIA jumped on the green bandwagon by releasing the GeForce 9600 GT Green Edition, promising an under-load TDP reduction of some 35W. Western Digital, too, has been espousing the green credentials of its recently-announced 2TB hard drive.

Being green is good, no matter which way you look at it, but the relationship between power-draw and cost is poorly understood by most. Therefore, Scan, a responsible, environmentally-friendly company, provides you with a select list of components/equipment that may be present in your home, and the associated cost of running them for pre-defined lengths of time.

The Cost

Electrical appliance Power-draw (watts) Cost per year (low-usage) Cost per year (mid-usage) Cost per year (high-usage) Cost per year (Max-usage, 24/7)
Sony 46W4500 46in, 1080p LCD TV (shop setting) 237 £21.07 £50.57 £88.49 £235.98
Sony 46W4500 46in, 1080p LCD TV (calibrated setting) 133 £11.82 £28.36 £49.64 £132.38
Sony BDP-S350 Blu-ray player 16 £1.42 £3.41 £5.96 £15.90
Sky HD+ box 28 £2.49 £5.98 £10.46 £27.89
Denon DM35DAB micro system 36 £3.20 £7.68 £13.44 £35.84
Microsoft Xbox 360 Falcon (Fallout 3) 114 £10.14 £24.33 £42.59 £113.57
Dell XPS M1330 laptop (charging, full power) 66 £5.87 £14.09 £24.65 £65.74
MSI PR211 laptop (charging, full power) 74 £6.58 £15.79 £27.37 £73.70
Intel Core 2 Duo PC(idle) 190 £16.90 £40.56 £70.98 £189.28
Intel Core 2 Duo PC (3D load) 288 £25.60 £61.44 £107.52 £286.82
Dell 3007WFP-HC monitor 142 £12.63 £30.31 £53.04 £141.46
Dell 2405FPW 88 £7.82 £18.77 £32.84 £87.58
Toshiba external 320GB drive 12 £1.07 £2.57 £4.49 £11.97
HP 6310 all-in-one fax 14 £1.24 £2.98 £5.21 £13.89
Creative I-Trigue 3200 speakers 12 £1.07 £2.57 £4.49 £11.97
Hotpoint larder fridge 35 N/A N/A N/A 34.86
Hotpoint larder freezer 38 N/A N/A N/A 37.84

The electricity price of 11.4p per kilowatt hour is based on a household using 1,000kWh per quarter and being on a competitive tariff such as British Gas' Websaver. Should the usage be more frugal, say 500kWh per quarter, the average cost goes up to 12.87ppkWh, and raising the electricity consumption to 2,000kWh per quarter - which is really, really heavy domestic consumption - decreases unit cost to 10.69ppkWh. We're taking the 11.4p cost, which includes VAT, into consideration.

Low-usage consumption is defined as running that particular appliance for three hours a day, five days a week. Mid-usage consumption is reckoned to be six hours a day, six days a week, and, finally, high-usage is calculated on the basis of nine hours per day, seven days a week. Of course, some folk leave on computers 24/7 and the final column, however unrealistic, reflects this. You wouldn't run an Xbox 360 24/7, would you, but the fridge and/or freezer would be on for such a period.

For example, straight of the box, the Sony 46W4500 TV, a tasty bit of kit, churns through almost 240W, because Sony sets up the 'shop' parameter to have a backlight brightness of 10/10. Reducing this to, say, four, which is perfectly adequate, and tweaking other settings saves you over 100W. Based on a high-usage pattern, that equates to almost £40 per year. Every little helps.

The standalone Sony Blu-ray player is frugal, and the Sky HD+ box has an auto-standby function that will reduce power, but even it will rip through almost £30 of 'leccy if left on 24/7. It doesn't sound like much in isolation, but begins to add up, rather quickly, when running for over 4,000 hours per year.

Gaming addicts may want to take a note of the Xbox 360 figure, observed whilst playing Fallout 3. Play a lot and it will cost you (or your parents) over £40 per year, too.

Killing me softly
The real killers are PCs, obviously, because they're usually switched on for multiple hours and consume a generous amount of watts in the process. Having a setup similar to the Core 2 Duo PC and Dell 3007WFP-HC monitor, described above, switched on for around 60 hours a week, and the scary thing is that it costs the 'office' some £120 a year when the PC's idling. Moving to an energy-efficient laptop could save almost £100, and that's for one person.

Exacerbating matters, should you happen to run multiple PCs the cost quickly spirals out of control. Run five high-specification machines on a 24/7 basis for distributed computing, a worthwhile cause, and you may face a leccy bill of close to £1,000 p.a. alone. Thinking about it, a super-high-end PC, including monitor, pulling 1kW under load, running 24/7, would cost around £1,000 in just juice. You can clearly see why data-centres are now built with power and cheapness-of-electricity in mind.

The obvious things to do
The table shows why paying attention power-draw is so important, as sensible, informed choices could save you significant money over the long run. Purchase an 80 PLUS PSU on your next round of upgrading, change that CPU to an energy-efficient model and ditch the high-end card, bought for form's sake, and replace it with a mid-range model, for example.

Switch off appliances that aren't used, think seriously about the total cost of ownership, over a number of years, rather than just the up-front outlay.

Invest in a cheap-ish watt-meter, or go for an extra layer of sophistication with something like the Eco-eye - they'll pay for themselves pretty quickly, we imagine.

It's clear that PCs are heavy energy polluters and, consequently, any means of reducing power-draw is a good idea. If one million UK people switched from a 350W-guzzling PC to a 50W laptop, used in a low-usage environment, we would collectively save some £27m worth of electricity per year. This increases to over £100m per year if evaluate under the heavy-usage criterion.

Scan is committed to helping the environment by educating customers on the need for energy-efficient computing. To that end, we will be releasing a new 'green' section on the website, designed with just this aim in mind.

In the meantime, switch off the plugs when not in use!