Berlin - Whether it's a smartphone, tablet, laptop or compact camera, the longer you use a device, the better it is for the environment.Factors that weigh on a gadget's lifespan vary - from the ability to switch out batteries or expand memory to the sturdiness of the housing to plentiful software updates to a long guarantee - reports German computer magazine c't.Laptops are better for the environment than desktops due to their lower power usage. Meanwhile, printers and monitors often come with quality certificates that promise energy efficiency and low levels of deadly substances used in production. That's less often the case with laptops, desktops or tablets, criticise experts. There is no such certificate for smartphones.To save energy, it's a good idea to unplug power-hungry devices when they're not in use, perhaps with a power strip that has an on/off switch. SellOtherwise older desktops, depending on the model, can consume between 2 and 15 watts of power while in standby, and not much less when they're asleep or off.Indeed, some wi-fi routers, projectors and laser printers use more than 10 watts while in standby mode. Some plasma televisions use up to 20 watts. There's less reason to worry about the power consumed on standby by laptops, ultrabooks, tablets or smartphones.To truly save energy with laptops or PCs, it's important to activate the hard drive standby mode. That's accessible in the operating system, under energy options, on Windows machines. Experts advise allowing between 10 and 20 minutes until shutdown when inactivity is noted.Sell old, used-out devices. Even broken machines can be harvested for their valuable components. They certainly should not be thrown away with the regular garbage. There's also the option, for the more adventurous, of trying to effect repairs, with help from guides online at sites like www.ifixit.com or www.tim.id.au.