With the UN Climate Conference (COP21) having recently wrapped up in Paris, it reminds us how much global warming remains a growing threat. In fact, 2014 was the hottest year on record and 14 out of the 15 warmest years in history happened within the 21st century.

More than 100 world leaders attended the conference to discuss international solutions towards limiting climate change, but how can we, the tech industry, also join in on the action?

Although we don’t use as much paper and plastic, the digital world – email especially – still uses energy. Between powering servers and parts used to build hardware, ICTs (Information and Communication Technologies) can also use a lot of energy.

It’s strange to think that even though you’ve replaced direct mail with electronic mail, you’re still leaving a carbon footprint, right? Let’s think about it this way – email isn’t simply sent from one computer to another. There’s quite a lot more that goes on behind the scenes. And each of these touchpoints require an energy source to power it. McAfee’s 2009 report on spam’s carbon footprint that a legitimate email emits on average 4 grams of CO2.

Supply servers

Email goes through a number of servers, SMTP, DNS, and a number of routers. Newer servers – newer data centers consume less energy. For example, more data centers are now using air cooling and water cooling as a more green alternative to using air conditioning to keep their servers cool. Air conditioning emits pollutants whereas air and water cooling work in a loop and are more energy efficient.


You know how daily calorie intake is calculated? Typically, if you search this up online or talk to a dietician they ask for your weight, height, and daily physical activity. The larger your build or the greater your activity, the more energy you exert and the more food you need to consume to power your body. The same goes for email. The larger the size of the email, the more energy it consumes. In fact, an email with a large attachment (anything over one MB) emits an average of 50 grams of CO2. That’s approximately ⅓ the carbon footprint of a can of Coca-Cola.

Canning spam

You’re probably thinking – “But wait, what about spam? How does that fit in the picture? Is all of this unwanted mail emitting a lot of CO2”? Spam filters are built to not only efficiently direct these unsolicited messages to your spam folder, but also so that each spam email only emits 0.3 grams of CO2.

Social footprint

Email is a fairly green communication channel when compared to social mediums like Facebook and Twitter.The average Facebook user emits 269 grams of CO2 per year, just browsing for personal use. Each tweet emits around 0.02 grams of CO2, which is fairly low but keep in mind Twitter sees 250 million daily tweets from its 130-140 million (estimated) active user base each day. To put all of this in perspective, car manufacturers have succeeded in limiting the average automobile’s CO2 emissions to around 129 grams per mile. When you breathe, you emit an average of 50 grams of CO2 per hour. That means the amount of CO2 you emit from an average day of browsing Facebook is equivalent to the amount you emit from simply breathing for five hours! Crazy to think about, right?

Ultimately these are average global figures, which means your own carbon footprint today can be significantly lower or higher.

As we mentioned earlier, the energy sources that power the servers and data centers your email is routed through can heavily impact the amount of CO2 your messages emit. For example, Google heavily promotes the greenness of its services (such as Gmail). Google promises that the cloud structure, is a more environmentally friendly solution than local hosting because it shares facilities between several entities. On top of that, Google uses renewable energy to run these solutions whereas there are many companies that still power their solutions off of fossil fuel sourced energy such as coal, gas and petrol.

There are many steps you can take to start reducing your email’s carbon footprint today. First, you can reduce the size of your messages by compressing the size of any images, using tools such as Photofiltre to lower their resolution or by avoiding large HTML elements. Also, make sure that the energy used to send your email is put to good use! Following email best practices such as getting permission before sending to our contacts and regularly cleaning and maintaining lists. Finally, if your contacts unsubscribe, remove them from your lists as soon as possible.

Overall, email proves to be a pretty green communication channel to send through. But, by paying attention to how we send and by following best practices, we can make sure we do our part to make it’s even more environmentally friendly.