Practical Home Energy Saving at shadlock.co.uk
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Updated: 01-Sep-2010
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Saving Electricity

Computers - General

 


Tip Of The Day: Switch off hubs and routers when not in use


Do you really know if your computer is switched off? Maybe it is in a standby or hibernation mode, even if it is powered off (according to the computer) it will still be drawing some power from the mains. Power measurements on a range of computers with ages varying from a few months to fours years gave a power consumption of between 5W and 13W even when powered off. Standby and hibernation modes gave even higher consumption. The situation with peripherals such as monitors, scanners and printers is no better. To see some examples look at the 2004, 2006 and 2008 Survey Results.

The easy answer is to make sure the computer and all peripherals are switched off at the mains. If you do need to leave the computer powered make sure it is in the most energy efficient mode possible compatible with the usage and make sure peripherals not needed are powered from a separate switched socket. An alternative is to power peripherals via a device such as an 'Intelliplug' which only powers the peripherals when the computer is powered.. There is a myth that powering down computers when they are not needed damages them - this is a load of rubbish.

Always make sure that the computer has been set up to power down it's drives and turn off the monitor if left unused for say ten minutes with a switch to standby mode after a further period of time (say another 10 minutes). Doing this can give considerable savings with the minor inconvenience the computer takes a few seconds to wake up after hitting a key. Screen savers look pretty but they contribute to energy waste, when the computer goes onto standby set the computer to blank the monitor instead. Click here for more details.

If you have a home network or even just a broadband connection ensure routers and/or hubs are switched off when not in use. This will give power savings of between 5W and 20W. If the computer has unused cards fitted (e.g. Modem) then remove them they all contribute to wasting energy.

If you use a laptop don't leave it on charge overnight since even when the battery is fully charged the power supply continues using a small amount of electricity continuously. Either use a time switch or unplug the charger when the battery is fully charged.

To enable my system to be energy efficient I use a time switch on the router and hub plus time switches on five of the six computers networked together. Because the computers are fully powered down I have modified the switching circuit to hard power on each computer when the power switches on, this gets around the problem that software auto switch on will not always work in this mode. Doing this enables things like backups and virus scans to be scheduled for overnight using cheap rate electricity. This just leaves the problem of powering down the computer as soon a scheduled job has completed.

Finding suitable software to shut down a computer or computers when a job had finished after an indeterminate time proved almost impossible so I wrote several pieces of software to do this. You are welcome to make use of them free for personal non commercial use.AllOff or AllOff Lite are designed to shutdown the host computer (and in the case of AllOff optionally one remote computer) when the host CPU load falls below a preset threshold or there has been no keyboard/mouse activity for a preset time. LANOff shuts down a host computer (and optionally up to four remote computers) when the monitored network connections are lost for a preset time.


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