Why your website's carbon footprint matters
The internet produces roughly the same CO2 emissions as the airline industry. Every website contributes - and most could be significantly lighter.
Here's a number that might surprise you: the internet is responsible for roughly 3.7% of global carbon emissions, about the same as the airline industry. Every page load, every image download, every JavaScript bundle executing in someone's browser uses energy, in the data centre, across the network, and on the user's device. Most websites are far heavier than they need to be, and most of us in the industry haven't given it much thought. Have you checked yours?
I started paying attention to this as part of my B Corp certification process. One of the assessment areas covers environmental impact, and it forced us to think seriously about the carbon footprint of the sites I build. The good news is that reducing a website's environmental impact aligns almost perfectly with making it faster and cheaper to run.
What makes a website heavy?
From what I've seen, the biggest culprits are images and JavaScript. The median web page in 2023 is around 2.3MB according to HTTP Archive, and images typically account for half of that. Unoptimised hero images, decorative backgrounds loaded at full resolution, product photos that haven't been compressed, it adds up quickly. JavaScript is the other major contributor, and it's more expensive than images because the browser has to download, parse, and execute it.
Every project I build now includes a performance budget that doubles as a carbon budget. I aim for pages under 500KB where possible. The specific things I do: serve images in WebP or AVIF format with proper sizing via srcset and sizes attributes; lazy-load anything below the fold; minimise JavaScript by using server-side rendering and only shipping client-side code where interactivity genuinely requires it; use system fonts or limit web fonts to two weights; choose green hosting providers that run on renewable energy.
The Website Carbon Calculator (websitecarbon.com) is a useful tool for benchmarking. It estimates the CO2 produced per page view based on the page weight and the energy source of the hosting provider. When I tested my own site, it came in cleaner than 90% of pages tested, but there was still room to improve, particularly around image optimisation.
The business case
Beyond the environmental argument, lighter websites are faster websites. Faster websites convert better, Google's research consistently shows that each additional second of load time increases bounce rates significantly. They also cost less to host, because you're transferring less data. And for businesses pursuing sustainability certifications or ESG reporting, being able to demonstrate that your digital presence is actively managed for environmental impact is increasingly valuable.
This isn't about perfection or hair-shirt minimalism. It's about being intentional. Every image, every script, every font file is a choice, and making those choices consciously rather than defaulting to the heaviest option is something every development team can do.
If you'd like to know how your current site performs, or you're planning a build and want to bake sustainability in from the start, give me a shout.
Chris Ryan
Managing Director
17+ years in full-stack web development, most of it leading teams agency-side across e-commerce, CMS platforms, and bespoke applications. Specialises in infrastructure, system integration, and data privacy, with hands-on experience as a Data Protection Officer. Founded Innatus Digital in 2020 to offer the kind of honest, technically-led partnership that he felt was missing from the agency world.