The Unsustainable Web

This web page weighs 0.65 MB.

The average web page weighs 2.08 MB.

From your Instagram photos to your Netflix queue, every byte of data that lives on the Internet requires energy to deliver – energy that is most likely produced from fossil fuels.

How does the Internet actually consume energy?

Before any data appears on your screen, it is stored in giant data centers that expend energy to keep computer systems running as well as to cool down any overheating. Then, it travels through a wired or wireless network, which needs electricity to power networking devices such as bridges and routers. Finally, your device itself consumes energy to process the delivered data, working hard to display your feed or stream your movie. Repeat this process for all 4.13 billion people connected to the web, and it’s clear that the Internet has a significant carbon footprint.

The amount of energy that the Internet consumes was investigated in a frequently cited 2015 report by Huawei researchers Anders Andrae and Tomas Edler. They concluded that the Internet, referred to as information and communication technology (ICT), was projected to make up 11% of global electricity consumption in 2020, for a total electricity demand of approximately 8,265 TWh (terawatt hours).

As of 2018, this is more than the electricity consumption of every country in the world apart from China and the United States. Further, it is estimated that the ICT industry accounts for roughly 2% of global greenhouse gas emissions, matching the carbon footprint of the entire air travel industry.

The environmental impact of Internet use is not often a focus in the curriculums of those who study technical subjects such as computer science, data science, or any other field that leads to a career in building online services. As such, this essay will provide an overview of the current conversation surrounding the energy consumption of the web by examining a few key players that are a part of it: data centers, technology companies, and web developers.

Data Centers

Behind the interfaces we see in our day-to-day Internet browsing routine are hundreds of data centers that store and manage data for every online service or application. In 2018, these digital factories were estimated to consume approximately 205 TWh of energy, which is roughly 1% of global energy demand.

The energy efficiency of current data center infrastructure certainly has room for improvement. Nicknamed “Data Center Alley”, Loudoun County in Northern Virginia boasts the largest cluster of data centers in the world, handling 70% of the world’s internet traffic. Despite this major energy demand, 85% of Virginia’s energy production came from non-renewable sources according to 2017 statistics reported by the United States Energy Information Administration. With Internet traffic projected to grow 24% annually, it is crucial that data centers are designed to be as energy efficient as possible, especially as they expand to meet demand.

Amazon's data center in Northern Virginia
An Amazon Web Services data center in Northern Virginia. Source: GeekWire

Technology Companies

Of course, data centers would not be operative if not for the companies that leverage data to create the digital products we interface with. Since 2010, Greenpeace, a non-governmental environmental organization, has been urging major technology companies to commit to some form of green energy initiative, such as switching to 100% renewably powered data centers or offsetting their company’s carbon dioxide emissions in general. According to their 2017 Clicking Clean report, dominant tech companies such as Facebook, Apple, and Google were among the first to make long-term clean energy commitments back in 2011-2012, catalyzing the prioritization of energy efficiency by more and more Internet companies.

In fact, many companies have honored their commitments by building data centers in geographic locations that are have greater supplies of renewable energy such as Finland and Denmark. Both Apple and Google boast data centers that are powered by 100% renewable energy, with Apple reporting to have prevented the emission of 2.1 million metric tons of carbon dioxide since 2011.

Google's data center in Finland
Google's data center in Hamina, Finland. Source: Google

Yet, there are still several companies that demonstrate a lack of transparency regarding the sustainability of their operations. Greenpeace specifically targeted Amazon Web Services (AWS), the largest cloud computing platform in the world, as “completely non-transparent about the energy footprint of its massive operations,” despite their commitment to 100% renewable energy in 2014.

Web Developers

Where does this leave web developers, the ones who are actually engineering the websites and applications that shape the web? Website Carbon Calculator, a website by a London-based agency, calculates the amount of CO2 produced every time someone visits a given URL. Their calculation involves the amount of data transferred, the energy consumption of serving that data, the carbon production of the site’s host, and finally, the website’s traffic. They conclude that the average website produces 4.61 grams of CO2 per page view.

While powering data centers with renewable energy is one approach to slow down the Internet’s carbon emissions, an alternative approach is to minimize the amount of data that is actually transferred. Certain website assets such as images, fonts, and scripts add significant bloat to websites and in turn, use nonessential bandwidth and energy to deliver to users.

For example, this website attempts to conserve energy in the following ways:

  • Content is type set in a system font. As of March 2020, the average web page makes five font requests and loads 127.9 KB in custom font files. Using fonts that are already pre-installed on a user’s operating system can bring the number of font requests down to zero. This site uses Helvetica, a font supported by most operating systems.
  • Images are compressed and used in moderation. Images are the primary culprit of page bloat and have been recorded to take up 1.03 MB/page – nearly half of the average web page’s weight. This website has two images, both compressed for a total of 0.27 MB.
  • Animations are implemented with CSS. Interactive features on a website are typically implemented in JavaScript. However, running less JavaScript improves the energy efficiency of a website as less CPU processing is required. This site uses browser-optimized CSS transitions in favor of programming any animations JavaScript.

Web developers can also choose to prioritize optimizing their websites for energy efficiency by choosing a green web host. The Green Web Foundation provides a directory of green hosts that power their servers with clean energy. Altogether, the strain of the global climate crisis may fall into the lap of web developers. Luckily, they have the means to reduce the carbon footprint of their work.


It is important to acknowledge that quantifying the carbon footprint of the Internet is a difficult task as there are several components that make up its infrastructure. However, as the Internet expands to support more data, users, and applications, its energy demand becomes nontrivial as does the need to mitigate any climate consequences.

All of this is to say that the Internet has a hidden environmental impact, even if it sometimes feels like its capacity is infinite. Data centers, technology companies, web developers, and anyone else who has a hand in defining our online experience should consider what a sustainable digital future might look like in the face of the rapidly growing web.

About This Site

This essay was authored by Caitlin Wang, a computer science student at Northeastern University. The source code for this site can be found here.