Website carbon footprint Low-carbon web design and greenwashing

According to the Global Carbon Project, if the internet were a country, it would be the fourth largest emitter of CO2 in the world. And your website contributes to this footprint.

Websites are made up of web pages. Each page can have a very different energy footprint. And website visitors could visit any number of your site’s pages. Therefore, when considering your web footprint, it makes more sense to think in terms of web pages, not websites.

Here’s my layperson’s explanation of how the carbon emissions of a web page are calculated. You can measure your own pages using a tool like the Website Carbon Calculator or Beacon.

The carbon emissions of a web page consist of:

1. Energy used by the data centre
Web pages are hosted on servers in data centres. The more data stored, the more energy is required.

2. Energy used to transfer the data
Energy is required to transfer your data from the data centre to the visitor’s device. The more data transferred, the more energy it takes for the visitor to load the web page. As you have no control over the source of electricity used by visitors, the carbon is calculated based on the global average carbon intensity of grid electricity.

3. Website traffic
Put the above two together and we get a good idea of the carbon per page, per visit. Multiply this by your average annual page views and you can estimate the total annual CO2 emissions for each web page.

The Website Carbon Calculator estimates that the median average emissions per page view are approximately 0.8g CO2 (July 2023).

1,000 visits a year = 800g
As much CO2 as boiling water for around 108 cups of tea

10,000 visits a year = 8kg.
As much CO2 as boiling water for around 1,080 cups of tea

100,000 visits a year = 80kg.
Roughly as much CO2 as driving a petrol car from London to Sheffield and back

These figures are for a single page. A website’s total annual page views are typically much higher, as most visitors will browse more than one page. It’s easy to see how 3,000, 30,000 or 300,000 total page views per year can quickly add up – and significantly increase the overall footprint.

These are not inconsequential amounts, and every website owner – and every website created by an agency – should take steps to reduce its carbon footprint. Fortunately, the actions that make the most difference are fairly easy and quick to implement. For example, I’ve applied these quick wins to this website – and this page emits just 0.02g CO2.

While it’s important to reduce the carbon footprint of websites, I’ve started to feel uneasy about how some websites and web design agencies present this. Given that emissions are relatively low for many websites with modest visitor numbers – and that it’s fairly straightforward to reduce the per-page footprint – websites and agencies that loudly promote their low-carbon credentials could come across as virtue signalling. Especially when a website is just one part of a much wider digital footprint – which also includes cloud storage, AI use, online software, social media, email newsletters, photo libraries, video hosting and more.

Some agencies are now marketing themselves as specialists in creating low-carbon websites. But unless you’re aiming to go to the nth degree, this isn’t a specialist service. I worry this could be disingenuous – misleading clients into thinking it’s something only certain agencies can offer and that it will significantly reduce their overall footprint.

The real impact of a digital agency isn’t in making efficient websites – it’s in who they choose to work for. If an agency builds a low-carbon site that helps a high-carbon business grow, it’s one step forward and a million back.

There is plenty of information on how to lower the carbon emissions of a web page, so I’m not going to repeat it. This guide by my colleague Chris Butterworth is probably the best guide to quick wins.

The only points I would add are:

Use responsive images
Load different sized images for different viewport sizes and pixel densities. Use large images for high-res desktops, small ones for mobiles – and several steps in between.

Avoid template websites
Pre-built websites that you customise, such as Squarespace and Wix, come with a lot of features, code and weight, most of which will never be used. It’s far better to start with a blank canvas and build up, only including what is needed. For this reason I use Kirby Content Management System (CMS). It is lightweight, quick and provides total control over the code. This avoids unnecessary features that slow down loading times and increase energy use.

Use fewer or no third-party add-ons
Analytic tracking scripts, ads and social embeds can add significant weight to pages.

Reducing the size of web pages is better for the environment, but it also means your pages will load faster – which visitors will appreciate – and search engines, in turn, rank fast-loading pages higher. So, it’s also good for your search engine optimisation.