What is ESG and why does your website have anything to do with it?
ESG — Environmental, Social, Governance. A few years ago, this sounded like corporate jargon that had nothing to do with smaller businesses. Now? In the UK, it is the standard. Companies employing over 250 people must report the carbon footprint of their entire supply chain — and pay attention — also their digital service suppliers. So if you are building a website or doing marketing for a British corporation, your digital carbon footprint goes into their report.
And here is a fact that surprises many: the internet generates around 3.7% of global CO₂ emissions. That is the same as the entire aviation industry — according to Carbon Trust data from 2025. Every page visit uses energy: the server processes the request, the network transmits data, your phone or computer displays it. A heavy page with tonnes of scripts and unoptimised images equals more energy and a bigger carbon footprint. It is that simple.
70% of large UK companies require ESG data from suppliers
The EcoVadis report is merciless here: 70% of FTSE 350 companies require environmental documentation from their suppliers. This is not a forecast — these are 2026 figures. For Polish businesses in the UK working with British corporations, the conclusion is simple — you need to show that you operate responsibly. And your website is the easiest place to prove it.
Before you think "greenwashing" — that is not what this is about. Sustainable web design is about concrete technical actions. Measurable. Verifiable. Smaller page weight, fewer server requests, cleaner code. And as a bonus — those same actions make your website faster, rank better in Google, and look better on phones. So this is not a sacrifice — it is pure benefit.
How clean code creates a low-carbon-footprint website
Sustainable web design stands on four legs: clean code, optimised resources, good infrastructure and conscious design. Let us break it down.
Clean, semantic HTML/CSS code
Every unnecessary kilobyte of code is energy. Pages built on heavy JavaScript frameworks (React, Angular) can weigh 2-5 MB. A well-written static site? 200-400 KB. The same visual effect, ten times less energy. As it happens, our website — the one you are reading right now — is built exactly that way.
What does that mean in practice? Semantic HTML5, modular CSS, minimum JavaScript. Every line of code must be justified. Can something be done in pure CSS instead of JS? We do it in CSS. Not because we are purists — because it is simply lighter and faster.
Image and multimedia optimisation
Images account for 50-70% of an average page weight. That is where the biggest savings potential lies. WebP instead of PNG — straight away 25-35% less. AVIF? Up to 50% less than JPEG. Add lazy loading (images only load when you scroll to them) and suddenly your page is twice as light.
Another thing most people do not know about — the srcset attribute. Thanks to it, the browser downloads an image matched to the screen size. Your phone does not download a 4K image prepared for a 27-inch monitor. Simple trick, enormous saving in energy and loading time.
Green hosting — servers on renewable energy
Hosting is a decision many do not think about, yet it has the biggest impact on a website carbon footprint. Data centres powered by 100% renewable energy — wind, solar, hydro — eliminate CO₂ emissions related to running your website. In the UK, you have choices: Krystal, Kualo, A2 Hosting — certified green hosting with servers in London.
It is also worth checking the PUE (Power Usage Effectiveness) rating. This measures how much energy goes to cooling and infrastructure versus the actual servers. The best data centres achieve a PUE below 1.2 — meaning almost all energy goes to what it should, and not to air conditioning.
4. Conscious design — less is more
Dark colour themes (dark mode) use less energy on OLED screens — black pixels are literally switched off. A minimalist interface with plenty of white space not only looks better but requires fewer resources to render. Limiting animations, autoplay video and infinite scrolling delivers concrete energy savings on the user side.
An average website generates around 0.5 g of CO₂ per page view. A site optimised according to sustainable web design principles can drop below 0.1 g — a fivefold reduction. At 10,000 monthly visits, that is a difference of around 48 kg of CO₂ per year — equivalent to 200 km of car travel.
Sustainable web design as a competitive edge in tenders
For Polish businesses in the UK bidding for contracts with British corporations, a website built according to sustainable web design principles is not a cost — it is an investment in competitiveness. Increasingly, requests for proposals (RFPs) include a section on ESG and sustainability. Being able to provide concrete data — page weight, CO₂ emission per view, green hosting certification — sets you apart from competitors who do not measure these things.
It works the other way too. If your company offers digital services — web design, marketing, hosting — you can offer clients "green" solutions as part of your value proposition. In the UK regulatory climate of 2026, that is an argument that speaks to finance directors and compliance departments.
Website audit — where to start?
The first step is measuring your website current carbon footprint. Tools like Website Carbon Calculator, Ecograder or Beacon perform an automatic audit and provide the result in grams of CO₂ per page view. That is your starting point for optimisation.
Next, it is worth carrying out a technical audit covering: page weight (target below 500 KB), number of HTTP requests (target below 30), cache utilisation, resource compression (Gzip/Brotli), image formats, and CSS and JavaScript minification.
The third element is assessing your hosting: does your provider use renewable energy? What is the PUE of the data centre? Is the server geographically close to your target group (for the UK market — in Great Britain)?
How MAC LEE DESIGNS implements sustainable web design
At MAC LEE DESIGNS, sustainable design is not an add-on — it is the foundation of our process. Every project starts with a performance and carbon footprint analysis. We build websites on clean, static HTML and CSS, eliminating the overhead of heavy frameworks. We use next-generation image formats (WebP, AVIF) with automatic fallback for older browsers.
Our websites are hosted on UK servers powered by renewable energy. This means we combine low latency (loading speed under 1 second) with a minimal carbon footprint. Every client receives an ESG-ready report with CO₂ emission metrics that they can use in their corporate reporting.
The dark colour palette of our designs is not just an aesthetic choice — it is a conscious reduction in energy consumption on OLED-screen devices. Minimalist typography, limited CSS animations and no autoplay video complete our sustainable design strategy.
Sustainable web design is not a trend — it is a response to real regulatory and business requirements in the UK of 2026. Clean code, optimised resources and green hosting create a website that is faster, cheaper to maintain and constitutes tangible proof of your company pro-environmental actions. In the ESG era, your website says more about you than you think.
Next step: check how your website fares on ESG
Want to know how much CO₂ your current website generates? Looking for a partner to build you a site compliant with the ESG requirements of British corporations? Check our sustainable web design offer or take our short quiz, and we will prepare a personalised Digital Roadmap with sustainable development recommendations for you.