A single desktop computer will consume approximately £75 of electricity 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 for the majority of users (insert ref.).
IT managers and end-users often decide to leave their computers on after they have finished using them for the following reasons:
- So that a central backup service can make a copy of files overnight
- So that a central service can install general software updates and security patches
- To allow access to a computer when off site e.g. to retrieve a file while at a conference
- To avoid waiting for a computer to start up from off
- So that a personal computer can also act as a web server or central file store
- A personal computer is used to keep another computer on ("keep alives")
- A computer is used to constantly filter emails so that email folders are organised when accessing messages through the web
- To allow spare computing capacity to be used by computer modelling projects e.g. SETI, climateprediction.net and GRID experiments in general
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 organisations will also have to make decisions on whether practices need to change to save CO2 emissions and money.
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"]