Every email you send and receive emits carbon. How much depends on many different factors, including:
- the age of your phone or laptop
- how long it takes to write and read the email
- whether there were any images or attachments
- how much energy it took to send and pass it through various data centres.
The carbon cost of an email
| Email type | Emissions (Co2e) |
|---|---|
| Spam email picked up by your filters | 0.03 g |
| Short email sent and received on a phone | 0.2 g |
| Short email sent and received on a laptop | 0.3 g |
| Long email that takes 10 minutes to write and 3 minutes to read, sent and delivered on a laptop | 17 g |
| Email blast that takes 10 minutes to write and sent to 100 people, of whom 1 reads it and the other 99 glance at it for 3 seconds to decide that they should ignore it | 26 g |
[Source: Carbon Literacy Project]
Junk mail?
An email newsletter generates around 10 grams of CO2, and 90% are never opened! [Source: Cleanfox]
Thirty-two billion trees would have to be planted every year to offset the pollution caused by unopened attachments, unread email and spam. [Source: Gerry McGovern, Digital is Physical]
According to Mike Berners-Lee: “Whilst the carbon footprint of an email isn’t huge, it’s a great illustration of the broader principle that cutting the waste out of our lives is good for our wellbeing and good for the environment.
“Every time we take a small step towards changing our behaviour, be that sending fewer emails or carrying a reusable coffee cup, we need to treat it as a reminder to ourselves and others that we care even more about the really big carbon decisions.” [Source: Ovo Energy]
How you can help
- Only send an email if you genuinely have something useful and relevant to say
- Review the company culture surrounding emails: e.g. suggest people don’t send quick messages such as “thank you!”. If every adult in the UK sent one less “thank you” email, it could save 16,433 tonnes of carbon a year – the equivalent to taking 3,334 diesel cars off the road or 81,1522 flights to Madrid [Source: Ovo Energy]
- Use alternative messaging tools such as Slack, which consume less energy
- Marie Kondo your inbox – hit unsubscribe to the emails that you no longer have the time or inclination to read
- Review your recipients – does everyone really need to be copied in?
- Take steps to avoid email shots going straight into Junk: ensure your email template is set up correctly and test before you send to all
- Reduce the file size and compress any images or attachments before you send them
- Don’t send large files on email, use WeTransfer, Google Drive or OneDrive instead
- Spellcheck, proofread and check for broken links before you hit send. Poor content is bound to generate unnecessary responses (more carbon!) and then you’ll have to edit and resend the message. This causes twice the harm to the planet
- Only include your email signature in new emails – switch it off for replies.
Message mindfully
Not all messaging apps are equal when it comes to energy consumption and carbon emissions.
The application with the best carbon impact average is Slack (0.035 gEqCO2) followed closely by Skype (0.043 gEqCO2) then Teams (0.055 gEqCO2), with a difference of 36% between the best and the worst. [Source: Greenspector]
How you can help
- Use Slack as your default messaging app
- Don’t send GIFs, PDFs and other files over messaging apps – send links to stored files instead.