How to reduce the carbon footprint of your devices: 12 ways that work

Turn the brightness down

Purdue University found brightness largely decides how much power a phone screen draws. A phone in light mode at 20% brightness used the same power as one in dark mode at 50%.²

Do this: switch on auto-brightness, then nudge the manual level down a notch indoors.

Use dark mode, but know what it really does

Dark mode saves power because OLED screens switch black pixels off. At normal indoor brightness the saving is small, as the chart shows.² LCD screens have a backlight, so they save far less, and we found no figures for laptops.

Do this: use it outdoors and on OLED phones.

Set devices to sleep sooner, and switch off properly

An idle screen still draws power. The US Department of Energy notes that ENERGY STAR monitors use two watts or less in sleep mode.³

Do this: set sleep to the shortest time your team can live with, and shut down overnight.

Send a link, not an attachment

One email can be anywhere from about 0.03g to 26g of CO2e. Long emails carrying files sit at the heavy end, and every inbox they reach stores its own copy.⁵

Do this: share a link to the file in your cloud storage. Everyone sees the latest version too.

Cut the noise

Unsubscribe from what you never read, empty your spam folder and skip the “thanks, received” reply. Email was about 0.3% of the global footprint in 2019, by Berners-Lee’s estimate.⁶ Treat this as a tidy-inbox habit that also saves your team time.

Use the smallest screen that works

For video, the screen matters most. The International Energy Agency found a 50-inch TV uses about 100 times the electricity of a phone.⁴

Do this: for a one-to-one call, use a laptop rather than the meeting room screen.

Download what you’ll rewatch, and drop the resolution

The IEA put an hour of streaming video in 2019 at around 36g of CO2, far below the viral claims.⁴ It still adds up across a team with video on all day.

Do this: save training videos instead of streaming them every time, and don’t default to the highest quality.

Close the tabs, update the software

Open tabs keep working in the background, and out-of-date software runs less efficiently and less securely. We found no trustworthy per-tab carbon figure, so we don’t give one.

Do this: close what you’re not using at lunch and at the end of the day, and accept updates when IT schedules them.

Compress images and video before you upload

Images make up roughly 40% of a typical web page’s weight.⁷ Lighter pages use less energy and load faster, which keeps visitors longer.

Do this: resize images to the size they display, use modern formats, compress video and turn on lazy loading.

Check your hosting, and trim the extras

Ask your web host whether its data centres run on renewable energy. Then cut what the page doesn’t need: autoplay video, trackers, heavy embeds, redirect chains and pages nobody visits.

Repair or upgrade before you replace

A slow laptop often just needs more memory, a new battery or a fresh drive. Most of its carbon went into making it, so keeping it working beats buying new.¹

Do this: before the next refresh, ask your IT provider one question: what would it cost to upgrade these instead?

Use it for longer, then pass it on

Every extra year spreads the carbon spent making it. The European Environmental Bureau found one more year of life for every EU notebook would save as much CO2 as taking 870,000 cars off the road.⁸ When a device is finished with, reuse beats recycling.

Do this: have the data securely erased, then pass the device on for reuse. Kit left in a drawer loses roughly 2% of its value a month.