Ask yourself this: will a fiddly thing with a flip-up screen improve your quality of life? No? So resist unless your phone is bleeping its last.

Dead Ringers? is a new exhibition at the Science Museum (www.sciencemuseum.org.uk/antenna/deadringers) that explores new phone technology and sustainability issues. The exhibition says that 1,712 phones are upgraded every hour in the UK and that although handsets are designed to last for ten years, the average length of our relationship with a mobile phone is a curt 18 months.

When one is chucked out, it usually ends up in a landfill site where its toxic contents — such as lead, arsenic and beryllium — will contaminate the planet. Much better to recycle your phone if you must upgrade. A phone brings in a minimum of £5 after it has been refurbished and sold abroad. Take it to an Action Aid or Oxfam shop, or you may find that your phone company has its own recycling service. Vodafone collects old phones to raise money for the National Autistic Society.

Future phones may have another kind of rebirth. The latest design, available only in Japan, has a biodegradable cover with a sunflower seed in it so that it can be buried in soil at the end of its life.

Should I shut down my computer during my lunch hour?

Depending on the length of your lunch, probably not. Setting your monitor to sleep is the thing to do, or you can try simply turning it off — powering the monitor accounts for 80 per cent of a computer’s energy consumption and contributes to a third of the electricity used in a modern office.

In most workplaces, the computers automatically switch to energy-saving mode if they are untouched for more than ten minutes.

Don’t confuse this with the screensaver function, which doesn’t save energy; in fact, it causes power to be drawn to the monitor for the display. For a home computer, I am told that it is easy to install the energy-saving function (go to Settings on the Start menu), although it might help to have a techy friend close by.

If you’re going to be away from your desk for several hours, a full shutdown is worthwhile. So, only those prone to lingering lunches — midday interludes that conclude with a guilty slope back to the office at half past four — should bother with the full shutdown.

And as a final word of caution, if there is anyone out there who still leaves their computer on overnight, I shall personally see to it that a mystery colleague slips into your seat and sends rogue e-mails on your behalf. Trust me, it won’t be pretty.

Do you have a green dilemma? E-mail it to ecoworrier@thetimes.co.uk