Why your website is wrecking the planet (and what you can do about it)

The internet isn't a cloud. It's a lot of very real machines.

We talk about “the cloud” as if our websites float about somewhere in the stratosphere, weightless and harmless. Unfortunately, that’s not quite the case.

Every time someone visits your website, a server somewhere wakes up (sometimes on the other side of the planet). This kicks off a chain of events: firstly, data travels through cables, routers and phone masts, then a laptop (or phone) does the work of turning it all into the page you see. All of that uses electricity, and much of that electricity STILL comes from burning fossil fuels.

Granted, one page view is tiny… but multiply it by every visitor, every page and every day of the year, and your website starts to have a very real carbon footprint that’s worth thinking about. Especially if you’re a company with a huge online presence - it really stacks up.

The good news? Fixing it usually makes your website faster, cheaper to run and better for your visitors too.

So what actually is website carbon?

Website carbon is the greenhouse gas produced by the electricity it takes to deliver and display your site. That energy is used in three specific places:

• Data centres - the servers that store your website and send it out whenever someone asks for it.
• Networks - the cables, routers and mobile masts that carry your data from server to visitor.
• Devices - the device you’re endlessly charging, be it your phone, tablet or laptop, which downloads your page and renders it on screen.

The easiest way to think about it is page weight, aka how much data a page makes someone download. The heavier the page, the more energy it takes to move it about, and therefore the more carbon it produces.

And web pages have been getting heavier. According to the HTTP Archive’s 2025 Web Almanac, the median mobile home page grew from about 845 KB in 2015 to around 2.3 MB in 2025. That’s roughly three times heavier in ten years(!!).

How big is the problem?

Well, it’s a lot bigger than most people expect. Researchers at Lancaster University estimated in 2021 that information and communication technology (ICT) accounts for a whopping 2.1-3.9% of all global greenhouse gas emissions. For comparison, aviation is often put at around 2%. Yep, crazy, right?

Zooming in on web pages specifically, the Website Carbon Calculator estimates that the average web page produces around 0.36g of CO₂ per page view.

That sounds like nothing, but it adds up quickly:

Based on the Website Carbon Calculator’s average of 0.36g per page view. Your site could be higher or lower.

And that’s just one site. Now picture every website on the internet doing the same.

Why should your business care?

While we all (hopefully) want a cleaner, more sustainable future, a lighter website is also simply a better website. Here’s why:

• It’s faster - your visitors get to see all the important stuff about you quicker, especially on mobile and slower connections.
• It’s better for SEO - Google uses page experience signals like Core Web Vitals, so making your pages speedier can actually help your rankings.
• It converts better - people don’t hang about waiting for slow pages (we’ve all been there and closed the tab). Faster sites keep visitors around long enough to enquire, book or buy.
• It costs less to run - smaller pages mean less bandwidth and storage, which can mean cheaper hosting.
• It’s more inclusive - lightweight sites work better for people on older devices, limited data plans or patchy signal. The more visitors the better, right?
• It shows your values - more and more customers, funders and partners care about sustainability, which is fantastic. A greener website is an easy, visible way to walk the talk and show you care too.

In other words, sustainable web design isn’t a sacrifice. It’s good design.

The usual suspects

So what’s making websites so heavy? These are the culprits I see most often:

• Huge images. I’ve had some horrendous experiences with people uploading ungodly 23MB+ images to sites I’ve managed, only for them to be used as a thumbnail. They take an age to load and eat up huge amounts of data. Images are the single biggest contributor to page weight, according to the HTTP Archive.
• Autoplay and background videos. That lovely full-screen video in your header? It might be downloading megabytes of data before anyone’s even scrolled. Not to mention it can be terrible for accessibility (more on that in a future blog!).
• Too much JavaScript. Page builders, sliders and animations all add code that has to be downloaded and processed. JavaScript is the second-biggest contributor to page weight.
• Third-party scripts. Analytics and tracking tools like GA4 and ad pixels, AI chat widgets, social media embeds… Every time you embed something into your site, it’s adding weight. So don’t add anything unless you 1000% need it.
• Too many fonts. Every typeface and every weight (light, regular, bold, italic…) is another file to download. Stick to a couple - your brand will thank you.
• Plugin overload. This is especially relevant for WordPress sites: every plugin can add its own scripts and styles to every single page, whether it’s needed there or not. Only add what you need and will actually use.
• Digital clutter. Old pages, forgotten PDFs and unused media that nobody visits but still need storing, backing up and hosting. Remove, remove, remove!

What you can do about it

Thankfully, you don’t need to rebuild your website from scratch. Here’s where to start.

Quick wins (this week)

• Compress your images. Resize them to the size they’re actually displayed at, and use modern formats like WebP or AVIF. This alone can cut page weight dramatically. As a rough benchmark, aim for under 200KB per image where you can, and much smaller for thumbnails.
• Lazy-load images and videos. Only load them when someone scrolls down to them, not all at once.
• Turn off autoplay. Let visitors choose to play a video, or swap a background video for a well-chosen image.

Bigger changes (worth planning in)

• Switch to green hosting - choose a host that runs on renewable energy. A really good source for this is The Green Web Foundation.
• Use caching and a CDN - caching stops your server rebuilding the same page over and over, whilst a CDN (content delivery network) serves your site from somewhere closer to your visitor.
• Design with sustainability in mind - fewer, more purposeful elements. Every image, animation and feature should earn its place on your site.
• Prune your content regularly - archive or delete old pages and files nobody visits. Chances are if you’ve forgotten it’s on there, it’s no longer useful!
• Offer a dark mode - on OLED screens, found in many modern phones, darker pixels use less energy. It also gives users more autonomy over how they use your site.

Progress, not perfection

Keeping it real here, every number in this post is an estimate. Measuring digital carbon is really tricky, and different tools use different methods. So don’t get too hung up on the exact figure. What matters is the direction of travel… you want your site lighter, faster and cleaner.

And no website is ever “zero carbon”. The aim isn’t perfection; instead, it’s making better choices - one image, plugin and page at a time - to help build a more sustainable digital future.

Practising what we preach

At Duology, we’ve put our own website through the same tests. It currently produces around 0.04g of CO₂ per page view, which is cleaner than 94% of pages tested by the Website Carbon Calculator.

It’s not perfect, but that’s the point. We’re always evolving and changing our site to be the best it can be (and hopefully helping you evolve yours too!).

Want a greener website?

If you’ve checked your site on the Website Carbon Calculator and don’t love the result, or you just don’t know where to begin, we can help. Duology offers a website carbon audit that looks at what’s weighing your site down and gives you a clear, practical plan to ensure your site is sustainable.

Let’s make your website lighter, faster and kinder to the planet together.

Book a call→

Sources

• Page Weight, 2025 Web Almanac, HTTP Archive
• Emissions from computing and ICT could be worse than previously thought, Lancaster University (2021)
• Website Carbon Calculator, Wholegrain Digital

100% human written. Any typos are free of charge!