The Energy in Emails
Do emails have a carbon footprint?
Short answer: yes.
They are written on a digital device, stored on a server, within a data centre than runs 24/7/365.
The Hidden Footprint of Emails
Mike Berners-Lee's How Bad Are BananasLink opens in a new window, estimates that each short “Thank you” email, has roughly six times more of a carbon footprint than a Teams Message, due to the server storage of copies of the email – one in your sent box and one in the receiving inbox(es).
As with everything not all emails are the same - if your average email takes ten minutes to write, and three minutes to read? That email’s carbon footprint has increased 56 times, due to the electrical consumption to write, read, and then store the file.
Why is the advice from IDG is to use a Branded Banner on just the first email? Well, that's because pictures and banners increase the files size. Making the strong first impression is key, and still recommended, but having a secondary footer for email chains without pictures or banners will save 66% of the carbon footprint for the consecutive emails.
Adding an attachment has a similar impact, which is why it's suggested to use SharePoint / OneDrive sharing links which have much less of an impact, and they also prevent the storage of ‘copies’ of documents.
The Scale of the Problem
With all this in mind, how many emails do you have in your inbox? Sent items? Calendar acceptance emails? Deleted items?
A quick survey of our team found the lowest estimation to be around 10,000 emails per person – presuming the middle example (17 gCO2e /email*) this would give roughly 17 kgCO2e, and for the roughly 8000 members of staff, this would result in 136 tCO2e, in email related carbon footprint. Per year.
So whilst each person may have a small impact – we are a community, and together we can reduce the impact of our digital footprint.
What can you do
1.React to email messages, reducing "Thank You" emails is an easy first step.
2.Use Teams for quick check ins, and group chats for planning that next catch up.
3.Have a different footer for your first and response messages.
4.Share links not files.
5.Delete your deleted items – at the very least all the calendar notifications!
6.Run a Information Tidy Day** on December 16th – clear out your OneDrive, the M: Drive and SharePoint sites, and help us reduce the overall storage space required.
*How Bad Are Bananas estimates that per person, the average email usage varies between 3 to 40kgs CO2e per annum.
**The Estates Information Tidy Day Link opens in a new window will help address growing data volumes, reduce storage costs, and mitigate risks associated with outdated or unnecessary information and support the upcoming M: Drive migration and ensure continued compliance with GDPR and internal data governance standards
Do you know that you can earn points on Warwick Green Rewards Link opens in a new windowby reducing your cloud footprint?
Log your cloud clean-up activity to earn Green Points and enter the draw to win vouchers you can use both on and off campus. You can also earn points through other sustainable actions like sustainable travel, saving energy, and more. Sign up now!
Cloud Services
Data Centres
The awareness is growing around how the increased demand for AI and cloud services is increasing the environmental impact of our digital infrastructure.
Data servers pose environmental concerns due to their high energy consumption, and the large amounts of water used for cooling. As with all hardware, the large data centres will also contribute to electronic waste.
The larger a data centre and the level of virtualised servers affect the efficiency of servers. On campus we operate (XX) square meters of data centres, which are monitored for their energy and water usage as part of our direct emissions. These are predicted to have a low (<188m2) medium (188-1858m2) high (>1858m2) efficiency. The M-Drive and H-Drive are ...
Cloud-based software is also an area of Scope 3 Carbon Reporting where spend-based reporting is thought to hyper-inflate estimated emissions due to limited comparable emission factors. As a Higher Education sector this is an area of known weakness, and Warwick is working with the sector to evaluate the alternative methods. The preferred method would be to use supplier provided information, either for our known service provision or for the company as a whole. Warwick is looking to implement methodology improvement in 25/26 in line with sector guidance and internal strategic alignment.
Microsoft 365
In 24/25, IDG obtained the University's Microsoft 365 Emission Impact Dashboard. This data reported significantly lower carbon impact over the current spend-based reporting method.
The Microsoft 365 software suite - OneDrive, TEAMs, SharePoint and Office - are an interconnected service provision which uses third-party data centres to reduce the direct, local storage capacity required on campus. This does not include the Co-pilot provision.
Microsoft estimate that their cloud based solutions are avoiding 9x the carbon emissions, based on the alternative being a low efficiency on-premises alternative.
Their Scope 1 and 2 emissions include the use of fuels for backup generators and purchased grid electricity, but the majority of the emissions Microsoft report are in their value chain (Scope 3) which includes the manufacturing and shipping of the physical servers.