Printers and photocopiers do not need to be running outside of school hours. However, many printers and photocopiers consume lots of power when the school is not open. Even ‘standby mode’ can consume more power than you think - often up to half as much power as when they are turned on. In comparison, desk and laptop computers use 95% less energy when they are in ‘standby mode.’
To reduce their consumption, buy an appliance monitor and plug it into each appliance to measure how much energy it uses overnight. You could get the pupils involved and run it as a science experiment. Energy Sparks has a pupil activity for this.
If you have identified a printer or photocopier which is using lots of electricity overnight, then it is generally best if you can automatically turn it off overnight. Some of the more expensive, advanced appliances allow you to do this automatically but others will require you to install a seven day timer. (Seven day timers are better than 24 hour timers because they allow appliances to be turned off all day on Saturdays and Sundays.)