You have probably seen “sustainable web design” used as a slogan more often than a specification.
It is worth asking what it actually looks like on a real, working website, because the answer is duller and more useful than the marketing suggests. It comes down to a handful of decisions: how heavy the pages are, how the images are handled, which fonts load and from where, what the hosting looks like, and how much the site tries to do on a single screen.
Sustainable web design examples are useful precisely because they let you check a claim against a real build rather than a slogan. Below are five projects, all cleared to be named, each modelled using the Sustainable Web Design model through the Website Carbon API and Google PageSpeed Insights. None of these figures is a live measurement of ongoing traffic; each is a modelled estimate of the page as built, which is the honest way to describe this kind of number.
What sustainable web design examples are actually measuring
A low carbon website example is not vague good practice. It sits inside a stated range. Across the client sites Agnikii has modelled, sites are performing at 0.06–0.20g per page view (modelled using the Sustainable Web Design model). It is worth checking against the Sustainable Web Design Model (opens in new tab) yourself before taking anyone’s word for where a site sits within it.
The mechanics behind that range are ordinary. Every byte a browser downloads has to travel across a network and get processed somewhere, and that costs energy. A page that sends less data, asks for fewer requests, and runs on efficient hosting will model lower every time, on any methodology. That is the whole basis of a sustainable website: not a certificate, but a set of decisions repeated on every page.
If you want to see where your own site sits before changing anything, a free website carbon audit gives you a modelled figure to start from, using the same methodology described above.
Example one: stripping out what a page doesn’t need
We Are Trailblazer needed a site that matched the pace of a growing SEO and PR agency without the page weight that usually comes with an active content operation. The build models at an A+ rating, 0.08g CO₂e per page view, with a Lighthouse score of 100. The work behind that number was straightforward: compressing images, refining the underlying code and removing plugins that were not earning their place on the page. Simplicity, not complexity, is what a lean build looks like from the inside.
RA Flatt Residential Lettings follows the same pattern from a different starting point: a lettings site built to grow visibility across Gloucestershire, modelling at an A+ rating, 0.08g CO₂e per page view, with a Lighthouse score of 99. Neither of these figures is a before-and-after; both describe the site as it currently stands, which is exactly what “what good looks like” should mean.
Example two: fonts, hosting and quiet accessibility
Neuranics, a Glasgow-based quantum sensing scale-up, needed WordPress maintenance that kept the site fast, secure and low carbon over time rather than just at launch. It models at an A+ rating, with a Lighthouse score of 96. Ongoing maintenance matters as much as the initial build: a site that starts light can still drift heavier as plugins, fonts and tracking scripts accumulate, which is why performance and carbon reporting need to be checked on a schedule, not just at handover.
Artis Bathrooms, a luxury Cotswolds bathroom designer, shows that a visually rich brand does not have to mean a heavy page. It models at an A rating, 0.12g CO₂e per page view, with a Lighthouse score of 91. Getting a design-led site into that range typically means being deliberate about image formats and sizes, and limiting how many custom fonts a page has to fetch before it renders anything at all.
Example three: the one site with a recorded before-and-after
Hills Quarry Products is the one project in this set where a genuine before-and-after exists, because the earlier PageSpeed scores were actually recorded rather than reconstructed after the fact. The mobile PageSpeed score moved from 49 to 75, and the desktop score moved from 70 to 100, following work to strip out what the earlier build called “digital drag.” The current model sits at an A rating, 0.12g CO₂e per page view, with a Lighthouse score of 96. Every other example above is a current-state figure, not an improvement claim, and it matters that the difference is stated plainly rather than implied.
Common mistakes when judging examples
The biggest mistake buyers make is trusting a headline number with no method attached. If an agency quotes a carbon figure with nothing behind it, no named model, no tool, no version, treat it as marketing rather than evidence. Several well-known sustainable design agencies publish strong opinions on the subject without publishing how they arrived at their own figures. That is not a reason to distrust the idea of sustainable web design; it is a reason to ask for the working, the same way you would ask an accountant to show their sums rather than just the total.
A second mistake is comparing a mean to a “best of” figure as though they are the same thing. A site’s average performance and its leanest page are different numbers, and a genuine example should say which one you are looking at.
Where to start
If you are briefing a redesign, or simply reviewing whether your current site holds up, start by checking your own numbers against the same kind of methodology used above. Look at page weight first, since it drives almost everything else: images, fonts and third-party scripts are usually the biggest single levers. Then check hosting and simplicity of layout, since both affect how much work a browser has to do on every visit. Agnikii’s Sustainable Web Design service builds against this from the first draft, and Website Sustainability Audits can tell you where an existing site currently sits.
For a wider look at the specific techniques behind these figures, lean website design principles, low carbon website design and lightweight web design go into more depth on page weight, images and code. If you have heard claims about sustainable design that sound too tidy to be true, common green web design myths is worth a read before you brief anyone.
None of this needs to be complicated to start. The fastest way to see where you stand is a free website carbon audit, which gives you a modelled figure against the same benchmark used throughout this article, with no obligation attached.