What is the carbon footprint for sending an email?

By Hayley Tsukayama, The Washington Post

A story started making the rounds recently about French energy regulators asking companies to cut back on email in order to save energy. It sort of sounds like a satirical piece — it did, in fact, end up in Reddit’s “Not the Onion” subsection — but the suggestion really does come from the French regulator, RTE.

Which got us thinking: How do our tech habits affect how much power we use and the environment? Finding an answer is harder than you may think. After all, the energy you use at your desk writing a typical email isn’t all the energy that an email uses. As the French warning indicates, there’s a whole infrastructure behind every message, which includes not only the electricity you use but also the energy it takes to store and transmit that information through data centers.

Many researchers have looked into the carbon footprint of these types of technology — meaning the amount of greenhouse gas produced to support the activity — to measure the impact they have on the environment. This is commonly expressed in the volume of carbon dioxide. Using more energy tends to produce a larger greenhouse gas emission, but using alternative forms of energy that don’t burn greenhouse gasses can also reduce a technology’s carbon footprint.

The carbon footprint of activities depend heavily on which companies you use, as different companies source their energy in different ways. Greenpeace and other environmental activists have long encouraged consumers to think about the environmental effects of their tech use.

Working off these and other sources, we were able to come up with some rough estimates about how your tech habits affect the environment. Your ultimate impact will, of course, depend on the way you power your own home — solar, wind, etc.

Email: The average spam email has a footprint equivalent to 0.3 g of carbon dioxide emissions (CO2e), according to carbon footprint expert Mike Berners-Lee’s 2010 book “How Bad are Bananas: The Carbon Footprint of Everything.” A normal email, according to that book, has a footprint of 4 g of CO2e, which accounts for the power data centers and computers spend sending, filtering and reading messages. An email with a “long and tiresome attachment” can have a carbon footprint of 50g CO2e.

Berners-Lee estimates that a typical year of incoming mail adds 300 lbs of emissions to a person’s carbon footprint, or the equivalent of “driving 200 miles in an average car.”

On a larger scale, he said the world’s data centers in 2010 accounted for 130 million tons of CO2e, or a quarter of a percent of the world’s global total. Berners-Lee projected that the world’s data centers will produce 250 to 340 million tons CO2e by 2020.

An hour of streaming video: Netflix itself said that, in 2014, that the average customer had a carbon footprint of 300g per year. Though, it must be said, that didn’t factor in the power consumed by devices — just the energy used delivering the service itself.

Netflix has since made its service carbon neutral, including the power it uses through Amazon Web Services and its own Open Connect program. Greenpeace did give Netflix a D in its annual report of tech companies environmental practices. The report that the firm has attained some of its carbon neutrality by buying offsets rather than encouraging its cloud providers to switch to cleaner energy source. That includes Amazon Web Services, which earned a C in the same report.

Watching television: The power consumption, and therefore the carbon footprint, of your television obviously depends quite a bit on what kind of television you have. If you want to find your own television’s consumption, try heading to the EnergyStar website, which will let you find products that have been certified as energy-efficient and give you their consumption information.

Again referring to Berner-Lee’s book, an hour of television viewing on an old 32-inch CRT television was rated at 84g CO2e for an hour’s worth of watching television, while a 15-inch LCD television generated 37 g. A 42-inch plasma television, however, generate the most with 240g CO2e.

Playing video games: Game consoles can be power hogs, at least according to a 2014 report from the Natural Resources Defense Council. As the NRDC put it: “As of January 18, 2014, just two months after their release, 8 million PS4 and Xbox One consoles had already been sold globally. Just these two months’ worth of sales will consume 8,000 gigawatt-hours of electricity and be responsible for the emissions of 3 million metric tons of CO2 over the life of the consoles.”

Game consoles are often put into a standby mode instead of being completely turned off, which contributes to the power they draw. Overall, the NRDC estimated at the time that game consoles drew as much electricity each year as the city of Houston. The study has not been repeated with the newest consoles each company has announced last year. Since the study, however, Microsoft introduced a new power-saving mode designed to reduce how much power it guzzles.

Streaming music: Here, again, the numbers are fuzzy — so fuzzy, in fact, that numbers were hard to come by at all. But a 2013 article cited in The Washington Post estimated that streaming an album 27 times used up the same amount of energy as producing and shipping a CD. So if you’re wondering whether streaming a song is better for the environment than buying it on CD, the devil is in the details.

In all cases, the question of how harmful any given activity’s energy use may depend in part on the company you’re using. Several companies, including Apple, Google and Netflix, have all committed to using clean sources of energy for their data centers — and, in many cases, are increasing the percentage of clean energy they’re using for their services each year.

If you’re worried about your energy bill, then paying attention to consumption alone is probably what you need to pay attention to the most. If you’re concerned about your carbon footprint, then researching how the companies you use source energy is also worth a look.