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Sustainable computing

The use of computers saves a lot of time and (in theory) paper. However, they also consume a great deal of energy. It is estimated that there are in excess of 20,000 computers in use within the University. The energy used by this number of machines running constantly for a week, is sufficient to light 840 homes for a year.

The simplest way to reduce energy consumption by computers is to:

Switch off your computer overnight and at weekends

Energy and cost savings of 70-80% can be made by simply switching off your machine when you are not at work. A computer that is never switched off runs for 8760 hours every year.  Only 20% of those are working hours (based on the University’s basic working week (36.5 hours) and four weeks holiday).

There will be some cases where this is not an appropriate course of action:

ADSM BACK-UPS are an essential part of the procedures in place to protect the University’s intellectual assets. The back-ups are conducted overnight and, in some departments, can only run if all computers are left on. Your administrator should be able to advise you about which day(s) you need to leave your machine on for this purpose.

Some staff running large and complex computer programs, may find that the time taken to boot up the computer each morning is detrimental to their work.

In these cases, only:

Switch off your monitor

This will halve the energy consumption during times when your computer is not in use. A typical hard-drive uses 80-100 watts of energy and a standard 17” TV-style monitor uses a further 90 watts. Consider also switching off your monitor when at lunch, or during meetings, lectures, seminars, etc.

REMEMBER: Screensavers do not save energy

A screensaver which is constantly moving requires the same amount of energy as when the computer is in use.

Local printers should be switched off when not required.

Find out if your computer has energy saving facilities and, if it does, enable them.

Most operating systems will automatically switch the monitor into stand-by mode if left unused for a specified period of time. Specify the shortest time delay possible — ideally 5 minutes. Newer computers will also allow the hard-drive to ‘spin-down’ if left idle. Some printers also have similar facilities.

The method for enabling energy-saving facilities varies. In Windows the controls can be accessed via ‘Power Management’ or ‘Display’ in the ‘Control Panel’. As power management systems can be troublesome with some networks, check with your administrator before enabling.

 If appropriate, break the habit of switching your computer on as soon as you arrive at work.

(This is likely to be most relevant to office workers). Although most aspects of our jobs today require the use of a computer, there are still some which do not. Wherever, possible, try to group together such tasks (e.g. telephone calls, dictation) and carry them out before you switch on your computer in the morning. Switching your machine on just 5 minutes later each day could reduce your computer use by a further 2%. Alternatively switch your computer off 5 minutes earlier, and carry out these tasks at the end of the day.