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Understanding The Environmental Impact of Slow Websites


8 min read


As countries worldwide struggle with power generation and carbon emissions, the environment has become an increasingly important talking point. Every day, millions, if not billions, of people consume and generate content on the internet, accessed through a plethora of devices 24 hours a day.

We need to consider the effect of the internet on our carbon footprint. Slow, content-heavy websites and apps have a huge environmental impact that should be discussed more.

In this article, I will discuss the carbon footprint of websites, what we can do to reduce the effects of carbon emissions online, what tools we can use to monitor and measure carbon emissions, and provide extra reading and best practices for keeping your websites green.

How Websites Contribute to Carbon Emissions

When we talk about carbon emissions, we’re talking about the energy (electricity) required to maintain a website online. Energy output on the web is not one-dimensional. The user's device, the server hosting the website, and the data centre handling the request require energy to do their respective jobs.

Not only is energy required for “hosting” or “serving” the website, but the integrity of the infrastructure, such as cooling down servers, also contributes. The more servers, the more infrastructure, and the more traffic mean that a large-scale website will contribute to more emissions.

Not every website is made equal. A significant publisher may include rich media like videos and large JavaScript files, requiring higher payloads and more bandwidth.

This is where performance optimisation plays an important role.

The Impact of Data Centres on Carbon Emissions

I have no doubt that most of you reading this post are familiar with “the edge” - a new computing term that attempts to serve static files and data as close to a user’s location as possible.

This is a paradoxical concept when it comes to carbon emissions.

Data centres are required in geographical locations to be able to proxy and serve requests made by end users. A data centre is a physical place in the real world, with servers running 24/7. Big companies like Amazon and Google have data centres all over the world in an attempt to serve their content faster.

To serve content more efficiently, data centres accumulate a substantial carbon footprint.

Strategies for Reducing The Carbon Footprint of a Website

There are multiple ways to improve the carbon footprint of a website. However, as most active individuals in the performance industry will tell you, it's not a one-size-fits-all approach.

Some strategies must take a step back to allow business units to perform their functions successfully. Ensuring a website is fast and lightweight can reduce its carbon footprint. Here are eight high-level strategies to review if you are interested in improving the carbon footprint of your website:

  1. SEO: the more optimised a page is, the more easily users can find the information they need through Google and similar platforms. The less time they spend looking through results they do not need, the less energy they consume.
  2. UX: User Experience is an essential factor in reducing carbon emissions. Suppose users can perform the actions they need to in an optimised and streamlined manner. In that case, we can optimise a user's flow from visiting a site to purchasing a product, reducing wasted resources and energy.
  3. Images: can have a heavy impact on carbon emissions. There are plenty of ways to optimise images from a technical standpoint, but you should ask yourself if the number of photos your site requests is necessary. Remember, the more images rendered on a site, the harder your device works - this compounds the energy requirement.
  4. Reduce Rich Media - Rich media, like videos, generally requires more resource-intensive transfers and computational power.
  5. Hosting Providers: Choose hosting providers with a high PUE (Power Usage Efficiency) rating
  6. Use Dark Mode - darker colours require less energy on the user's device.
  7. Static Files and The Edge: Where possible, use static websites and host them on “the edge” - this inevitably leads to lower payloads, quicker page speed and more optimised delivery.
  8. Use less JavaScript: JavaScript is a giant resource hog - try to ensure that your website uses as little JavaScript as humanly possible.

Consider using an energy-efficient hosting provider as a website owner. “Green” hosting providers use renewable energy to power and cool-down server infrastructure, which can dramatically reduce carbon emissions.

Valuable Tools for Monitoring and Measuring Carbon Emissions

Below are some tools I have recently come across that attempt to provide insight into the carbon footprint of a website.

The Sustainable Web Manifesto

The Sustainable Web Manifesto is a collection of guiding principles that can help agencies and developers build a more lightweight and efficient web. The following principles guide the manifesto:

  1. Clean: The services we provide and use will be powered by renewable energy.
  2. Efficient: Our products and services will use the least energy and material resources possible.
  3. Open: The products and services we provide will be accessible, allow for the open exchange of information, and allow users to control their data.
  4. Honest: Our products and services will not mislead or exploit users in their design or content.
  5. Regenerative: The products and services we provide will support an economy that nourishes people and the planet.
  6. Resilient: The products and services we provide will function in the times and places where people need them most.

Further Reading


The internet is a great contributor to carbon emissions. As web performance techniques become more and more solidified into development cycles, we’ll hopefully be able to offset our carbon footprint.

It's essential to know how websites affect carbon emissions and what we can do to reduce that footprint. Ensure that you work with cross-discipline departments to provide a fast and efficient user experience on your site. Use the tools available to you to monitor and measure carbon emissions.

The goal… let's make the web a sustainable place for everyone.

Profile of Daine

Written by Daine Mawer. Thanks for reading! Im always posting new content. If you liked what you read, please subscribe to my RSS feed or follow me on Github, Twitter or LinkedIn. Im also always on the look out for new oppurtunities, engagements, contract work or just coffee! So please dont hesitate to reach out.