Desktop computers cost approximately £75 per year if they are left on all the time. If they are put in a low power state when not in use this cost is likely to fall to £15 (insert ref.). Computers are often left on all the time for some of the following reasons:
- An external service needs access a computer e.g. to create a backup copy of files stored on the computer
- An individual needs to access their computer e.g. to retrieve a file while at a conference
- An individual wants to avoid waiting for a computer to start up
- A computer is used to keep another computer on
- A computer is used to filter emails all the time
- Spare computing capacity is 'donated' to science experiments
Many of these reasons mean that computers are being left on 'just in case' they are needed which means inevitably that there is likely to be extensive periods of time that computers are consuming electricity without doing useful work. Tools can be provided for IT managers and end-users that support the objective of minimising this wasted energy but as organisations will also have to make decisions on whether any practices need to change because they are simply too costly.
Tools and techniques
Waking computers up remotely
It is possible to provide the ability for IT managers and end-users to wake computers that they own using another computer. By providing a facility to turn computers on remotely, it becomes possible to ask people to turn their computers to low power states more often. For instance, many organisations will ask their staff to leave their computers on so that the a backup service can access the hard drive and create a copy of files. If computers can be woken up by the backup service then users can switch them off without disrupting this essential activity. This same logic applies to other services that may need access to a computer more regularly e.g. services that install software updates, anti-virus checking and so on.
Case study: University of Oxford
The University of Oxford developed a wake-on-LAN infrastructure that enables IT officers, end-users and 3rd party software to wake computers remotely. ["lcict:wol"]
Switching computers off automatically