Reducing Energy Use

Every device left running draws electrical energy, and much of that energy is generated by burning fossil fuels, which releases carbon dioxide. Using less energy while you own a device therefore lowers its environmental impact.

What a user can do on a phone or tablet

The choices you make while using a device change how much energy it needs:

• Turn off wireless connections you are not using. The aerials keep searching for a signal even when nothing is being sent, and that searching costs energy, so switching them off or using flight mode stops it.
• Close apps you have finished with. A game or a video editor left open in the background keeps the processor busy, so closing it lets the device rest and the battery last longer.
• Reduce how often apps check for messages. An app set to check every minute wakes the device constantly; checking every half an hour lets it stay idle.
• Install updates. Updates often include better power management, so the same jobs are done with less energy.
• Switch on power-saving mode. It dims the screen, restricts background activity and slows the processor, so each charge lasts longer.

For example, a student heading off on a two-day residential trip with no charger keeps the phone alive by using flight mode between tasks, closing the video editor left running and turning on power-saving mode after lunch. The phone lasts the trip and the charger stays in the bag.

What an organisation can do

A school, health centre or warehouse office may run hundreds of machines, so a small saving on each one adds up.

• Set computers to sleep when idle. A power setting that suspends a computer after ten minutes without a keystroke stops it drawing full power while nobody is working, and it wakes again the moment it is needed.
• Put displays on standby after inactivity. A monitor or projector left glowing across a lunch break still draws power and heats the room, so a setting that switches it to standby after a few idle minutes saves energy.
• Stop storage devices running when idle. A hard disk that keeps spinning when nothing is being read or written wastes energy, so letting it slow to a stop until the next file is opened saves power.